Co-reporter:Sebastian Bauer, Christian Serre, Thomas Devic, Patricia Horcajada, Jérôme Marrot, Gérard Férey and Norbert Stock
Inorganic Chemistry September 1, 2008 Volume 47(Issue 17) pp:7568-7576
Publication Date(Web):August 6, 2008
DOI:10.1021/ic800538r
Through the use of high-throughput methods, solvothermal reactions of FeCl3 and 2-aminoterephthalic acid in protic as well as aprotic reaction media were systematically studied. Thus, the fields of formation of the isoreticular structures of MIL-53, MIL-88, and MIL-101 based on Fe(III) and aminoterephthalate could be identified for the first time. The resulting 3D framework materials with amino-functionalized pores have been characterized using X-ray diffraction; IR spectroscopy; and thermogravimetric, elemental, and energy dispersive X-ray analysis. Due to the applied high-throughput method, a high density of information was obtained in a short period of time, which allows the extraction of important reaction trends and contributes to a better understanding of the role of compositional as well as process parameters in the synthesis of inorganic−organic hybrid materials. We have found that the nature of the reaction medium has the most profound impact on structure formation. Furthermore, the concentration of the starting mixture (i.e., the solvent content) and the temperature have also been identified as key parameters for the formation of the different hybrid phases.
Co-reporter:Karen Markey, Martin Krüger, Tomasz Seidler, Helge Reinsch, Thierry Verbiest, Dirk E. De Vos, Benoît Champagne, Norbert Stock, and Monique A. van der Veen
The Journal of Physical Chemistry C November 16, 2017 Volume 121(Issue 45) pp:25509-25509
Publication Date(Web):October 17, 2017
DOI:10.1021/acs.jpcc.7b09190
p-Nitroaniline presents the typical motif of a second-order nonlinear optically (NLO) active molecule. However, because of its crystallization in an antiparallel and hence centrosymmetric structure, the NLO activity is lost. In this contribution, the p-nitroaniline motif was built successfully into the MIL-53 metal–organic framework. More precisely, MIL-53 was synthesized with 2-amino-5-nitroterephthalate as organic linker, with Al3+, Ga3+, or In3+ as inorganic cation. The Al and Ga structures are polar, as confirmed by second-harmonic generation microscopy, yielding stable NLO materials. Indeed, they contain a 22–36% surplus of the dipolar 2-amino-5-nitro-terephthalate oriented in a parallel fashion. The indium compound was shown to be less crystalline and centrosymmetric. Ab initio modeling of the second-order NLO response shows that the Al and Ga materials show a response comparable to typical inorganic commercial NLO materials such as KDP. As a hybrid material, capable of low-temperature synthesis and processing and the ultrafast NLO responses associated with organic materials, this material can potentially provide an interesting venue for applications with respect to traditional inorganic NLO materials.
Co-reporter:Martin Krüger, A. Ken Inge, Helge Reinsch, Yuan-Han Li, Mohammad Wahiduzzaman, Chia-Her Lin, Sue-Lein Wang, Guillaume Maurin, and Norbert Stock
Inorganic Chemistry May 15, 2017 Volume 56(Issue 10) pp:5851-5851
Publication Date(Web):April 28, 2017
DOI:10.1021/acs.inorgchem.7b00202
The in situ and systematic high-throughput investigation of the system Al3+/4,4′-benzophenonedicarboxylic acid (H2BPDC)/DMF/H2O in the presence of various additives was carried out, and a new Al-MOF of composition [Al(OH)(BPDC)], denoted as CAU-21-BPDC, was obtained. Its crystal structure was determined from single-crystal X-ray diffraction data (space group I422, a = b = 17.2528(7) Å, c = 23.864(1) Å). The structure is built up by octanuclear rings of cis corner-sharing AlO6 polyhedra forming the inorganic building unit (IBU). These {Al8O8} IBUs are arranged in a bcu packing and connected via BPDC2– ions in a way that each IBU is linked via two linker molecules to each of the eight adjacent IBUs. Thus, accessible, one-dimensional modulated pores with a diameter between 3.6 and 6.5 Å are formed. In addition, tetrahedral cavities are formed by the BPDC2– linker molecules. The framework of CAU-21-BPDC is polymorphous with that of CAU-8-BPDC, which contains one-dimensional chains of trans corner-sharing AlO6 polyhedra connected by BPDC2– ions. Replacing H2BPDC by 4,4′-oxydibenzoic acid (H2ODB), which contains an oxygen atom between the phenyl rings instead of a keto group, leads to the synthesis of Al-MOFs isoreticular with CAU-8-BPDC and CAU-21-BPDC. In addition, a coordination polymer, [Al(HODB)2(OH)], was discovered and structurally characterized. The structure of CAU-8-ODB was refined from powder X-ray diffraction data, while a Pawley refinement was carried out for CAU-21-ODB to determine the lattice parameters and confirm phase purity. The structure of CAU-21-ODB was confirmed using density functional theory (DFT) calculations. A thorough characterization shows that the CAU-8 and CAU-21-type structures are stable up to 350 and 300 °C in air, respectively, almost independent of the linker molecules incorporated. The former MOFs are porous toward N2 and CO2, while the latter only adsorb CO2.
Co-reporter:Timo Rhauderwiek, Niclas Heidenreich, Helge Reinsch, Sigurd Øien-Ødegaard, Kirill A. Lomachenko, Uta Rütt, Alexander V. Soldatov, Karl Petter Lillerud, and Norbert Stock
Crystal Growth & Design June 7, 2017 Volume 17(Issue 6) pp:3462-3462
Publication Date(Web):May 8, 2017
DOI:10.1021/acs.cgd.7b00450
The four porphyrin-based metal–organic frameworks (MOFs) containing Ce3+ ions, [Ce4(H2TCPP)3(DMF)2(H2O)4] (CAU-18), [Ce4(H2TCPP)3]·22H2O (CAU-18a), [Ce3(H2TCPP)2(BA-X)(HBA-X/H2O)2]·2HBA-X·nH2O (CAU-19-X with X = H, 2Cl, 3Cl, 4Cl, 3CO2H, 4NH2, 4NO2, HBA = C7H4O2), and [Ce2(H2TCPP)(C7H4O2NO2)2]·2DMF (Ce-PMOF-4NO2) were synthesized using the linker 4-tetracarboxyphenylporphyrin (H6TCPP). The formation of the respective MOFs depends mainly on the presence of a coligand in the synthesis mixture. CAU-18 was obtained in the absence of a coligand, while CAU-19-X was observed when the benzoic acid derivative HBA-X (X = H, 2Cl, 3Cl, 4Cl, 3CO2H, 4NH2) was added. In the case that HBA-4NO2 was used as a coligand, yet another compound Ce-PMOF-4NO2 is obtained. The structures of CAU-18 and CAU-19-H were determined from single crystal X-ray diffraction data, while the structure of Ce-PMOF-4NO2 was refined from powder X-ray diffraction data by the Rietveld method. Activation of CAU-18 and Ce-PMOF-4NO2 resulted in phase transformations. Thermal treatment of CAU-18 at 250 °C leads to CAU-18a, which is porous toward N2 and H2O, while treatment of Ce-PMOF-4NO2 in organic solvents at 70 °C leads to the formation of CAU-19-4NO2, which cannot be synthesized directly. All CAU-19-X compounds are porous toward N2 and H2O, and the specific surface areas vary between 330 and 600 m2 g–1 depending on the size of the incorporated coligand. CAU-18, CAU-18a, and CAU-19-X are thermally stable in air up to 330 °C and chemically stable in H2O and all tested organic solvents. Ce L3-edge X-ray absorption near edge structure measurements revealed that exclusively Ce3+ ions are present in the title compounds, despite the use of (NH4)2[Ce(NO3)6] in all syntheses. In addition, the crystallization of CAU-18 and CAU-19-H was investigated in situ by synchrotron powder X-ray diffraction at DESY, Hamburg, using reaction temperatures between 110 and 130 °C. The data were evaluated using the approach by Gualtieri to determine the probability of nucleation (Pn) and the Arrhenius activation energy for nucleation (kn) and crystal growth (kg). The Arrhenius activation energies for the nucleation were determined as 47(2) and 56(3) kJ mol–1 and for crystal growth 45(4) and 58(5) kJ mol–1 for CAU-18 and CAU-19-H, respectively. The induction time (tind), in which no crystalline products are detected, and the total reaction time to achieve full conversion (tcom) are shortened at higher temperatures. Furthermore, the maximum of the probability of nucleation is shifted to earlier reaction times with increasing temperature.
Co-reporter:Martin Lammert, Christian Glißmann, Helge Reinsch, and Norbert Stock
Crystal Growth & Design 2017 Volume 17(Issue 3) pp:
Publication Date(Web):November 21, 2016
DOI:10.1021/acs.cgd.6b01512
We report on the applicability of an easy general synthesis procedure for the formation of Ce(IV)-MOFs which contain hexanuclear clusters. Thus, the series of Ce(IV)-based MOFs isoreticular to their Zr analogues has been extended to reo and spn topologies. Four new MOFs denoted as Ce-UiO-66-BPyDC [Ce6(μ3-O)4(μ3-OH)4(BPyDC)6] (BPyDC2– = 2,2′-bipyridine-5,5′-dicarboxylate), Ce-DUT-67-PZDC [Ce6(μ3-O)4(μ3-OH)4(PZDC)4(OH)4(H2O)4] (PZDC2– = 3,5-pyrazoledicarboxylate), Ce-DUT-67-TDC [Ce6(μ3-O)4(μ3-OH)4(TDC)4(OH)4(H2O)4] (TDC2– = 2,5-thiophenedicarboxylate), and Ce-MOF-808 [Ce6(μ3-O)4(μ3-OH)4(BTC)2(OH)6(H2O)6] (BTC3– = benzene-1,3,5-tricarboxylate) were obtained under mild reaction conditions (100 °C) and after short reaction times (15 min) using a modulated synthesis approach. The MOFs differ in their connectivity of the [Ce6O4(OH)4(−CO2)x] (x = 12, 8, 6) cluster, the geometry of the organic linker molecules (linear and bent dicarboxylic acids, tricarboxylic acid), and the resulting topology (fcu, reo, spn). The structures of all Ce-MOFs were confirmed using PXRD data by Rietveld refinement and Le Bail fitting. The heterocyclic aromatic dicarboxylic acids H2PZDC and H2TDC lead to MOFs which are both isostructural to DUT-67 due to the similar linker geometries. Ce-UiO-66-BPyDC and Ce-MOF-808 are thermally stable up to 330 and 150 °C, respectively, as proven by VT-PXRD measurements. N2 sorption experiments reveal large specific surface areas of 2120 m2 g–1 for Ce-UiO-66-BPyDC and 1725 m2 g–1 for Ce-MOF-808.
Co-reporter:Martin Krüger, Helge Reinsch, A. Ken Inge, Norbert Stock
Microporous and Mesoporous Materials 2017 Volume 249(Volume 249) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.micromeso.2017.04.054
•The mixed-linker approach was used to control the degree of functionalization of CAU-10.•Strong dependencies of the degree of fluorination were observed in sorption measurements.•CAU-10 was also obtained with an extended linker molecule (H3TATB).•The tricarboxylic acid H3TATB connects as a dianion the inorganic building units.•CAU-10-HTATB exhibits a similar high thermal stability compared to other CAU-10 derivatives.The systematic investigation of the solvothermal system Al3+/5-fluoroisophthalic acid (H2mBDC-5F)/isophthalic acid (H2mBDC)/DMF/H2O through a mixed-linker approach led to new mixed-linker CAU-10 derivatives containing 11, 28 and 44% of fluorinated linker molecules (denoted as CAU-10-H/F11, CAU-10-H/F28 and CAU-10-H/F44, respectively), as determined by NMR spectroscopy. The crystal structure of CAU-10-H/F28 was determined using the Rietveld method (space group I41md, a = b = 21.3075(5), c = 10.7101(3) Å). The structure is built up by helical chains composed of cis corner-sharing AlO6 polyhedra. Each of these helices is interconnected to four adjacent helices with alternating rotational orientation through the carboxylate groups of mBDC2- linker molecules. Thus, accessible, square-shaped channels are formed. Sorption measurements revealed a high dependency of the adsorbed amount of gas on the degree of fluorination. With increasing fluorination, the total uptake decreases in N2, H2 and H2O sorption experiments and the hydrophobic character of the pores increases.In addition, an extended CAU-10 derivative, CAU-10-HTATB, was discovered using the tricarboxylic acid 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid (H3TATB) during the high-throughput investigation of the system Al3+/H3TATB/DMF/H2O. This new MOF, which was denoted CAU-10-HTATB, was thoroughly characterized using IR spectroscopy, thermogravimetric and elemental analysis, temperature dependent powder X-ray diffraction (PXRD) and sorption measurements. Although the compound is thermally stable up to 400 °C according to temperature-dependent PXRD measurements, it is not porous towards N2 molecules. The structure of CAU-10-HTATB could be also refined from PXRD data using the Rietveld method (space group I41/a, a = b = 36.438 (1), c = 10.9373 (9) Å).Download high-res image (230KB)Download full-size image
Co-reporter:Helge Reinsch
Dalton Transactions 2017 vol. 46(Issue 26) pp:8339-8349
Publication Date(Web):2017/07/04
DOI:10.1039/C7DT01115F
This perspective highlights some studies and insights in the synthesis of metal–organic frameworks (MOFs) in a brief and comprehensive manner. The understanding of the synthesis procedures investigated by in and ex situ methods is of special interest since knowledge on the nucleation and crystallisation mechanism will ideally lead to an improved control over product formation. The prospective developments associated with the manufacturing of such materials (or devices consisting thereof) are discussed as well. A major challenge is the adjustment of the synthesis conditions to yield quantities suitable for real life applications. Last but not least, vast opportunities are yet to be explored involving the synthesis of both known and novel compounds. Thus the crucial points involving the synthesis of MOFs summarized in this perspective are rationalisation, application and exploration. For each subtopic we have also attempted to anticipate future challenges and developments.
Co-reporter:M. Lammert;C. Glißmann;N. Stock
Dalton Transactions 2017 vol. 46(Issue 8) pp:2425-2429
Publication Date(Web):2017/02/21
DOI:10.1039/C7DT00259A
A series of solid solutions of bimetallic Ce/Zr-UiO-66 and -MOF-808 compounds with a varying ratio of Ce4+ to Zr4+ were obtained under mild reaction conditions within 15 min. The lattice parameters of the mixed-metal compounds are in accordance with Vegard's law. Samples with Ce ≤20 at% exhibit an enhanced thermal stability, better resistance against acids and smaller particle sizes.
Co-reporter:Amarajothi Dhakshinamoorthy;Niclas Heidenreich;Dirk Lenzen
CrystEngComm (1999-Present) 2017 vol. 19(Issue 29) pp:4187-4193
Publication Date(Web):2017/07/27
DOI:10.1039/C6CE02664H
The metal–organic frameworks (MOFs) CAU-1-NH2 ([Al4(OH)2(OCH3)4(p-BDC-NH2)3], (p-BDC-NH2)2− = 2-aminoterephthalate) and CAU-10-NH2 ([Al(OH)(m-BDC-NH2)], (m-BDC-NH2)2− = 5-aminoisophthalate) which possess two different pore sizes were studied for their catalytic activity as heterogeneous solid base catalysts in the Knoevenagel condensation reaction between benzaldehyde and malononitrile under mild reaction conditions (40 °C, 7 h, ethanol). For comparison, isoreticular MOFs containing a smaller amount of –NH2 groups (CAU-1-NH2/H) or no –NH2 groups (CAU-10-H) were synthesized. A two-step synthesis route including the synthesis of CAU-1-NH2 and its use as crystal seeds was developed to obtain the mixed-linker CAU-1-NH2/H compound. Only for CAU-1-NH2, up to 100% selectivity towards the desired Knoevenagel condensation product is observed. Hence, the catalytic activity of CAU-1-NH2 was tested between various benzaldehydes containing different substituents with malononitrile. By employing benzaldehyde and malononitrile as the starting materials, it is found that the mixed-linker MOF CAU-1-NH2/H catalyses the formation of the acetal (benzaldehyde diethyl acetal), while both CAU-10 materials lead to mixtures of the two products. Furthermore, the catalyst stability was also examined through reusability and leaching experiments and it is observed that the catalyst can be reused with no significant drop in its activity.
Co-reporter:Amarajothi Dhakshinamoorthy;Niclas Heidenreich;Dirk Lenzen
CrystEngComm (1999-Present) 2017 vol. 19(Issue 29) pp:4187-4193
Publication Date(Web):2017/07/27
DOI:10.1039/C6CE02664H
The metal–organic frameworks (MOFs) CAU-1-NH2 ([Al4(OH)2(OCH3)4(p-BDC-NH2)3], (p-BDC-NH2)2− = 2-aminoterephthalate) and CAU-10-NH2 ([Al(OH)(m-BDC-NH2)], (m-BDC-NH2)2− = 5-aminoisophthalate) which possess two different pore sizes were studied for their catalytic activity as heterogeneous solid base catalysts in the Knoevenagel condensation reaction between benzaldehyde and malononitrile under mild reaction conditions (40 °C, 7 h, ethanol). For comparison, isoreticular MOFs containing a smaller amount of –NH2 groups (CAU-1-NH2/H) or no –NH2 groups (CAU-10-H) were synthesized. A two-step synthesis route including the synthesis of CAU-1-NH2 and its use as crystal seeds was developed to obtain the mixed-linker CAU-1-NH2/H compound. Only for CAU-1-NH2, up to 100% selectivity towards the desired Knoevenagel condensation product is observed. Hence, the catalytic activity of CAU-1-NH2 was tested between various benzaldehydes containing different substituents with malononitrile. By employing benzaldehyde and malononitrile as the starting materials, it is found that the mixed-linker MOF CAU-1-NH2/H catalyses the formation of the acetal (benzaldehyde diethyl acetal), while both CAU-10 materials lead to mixtures of the two products. Furthermore, the catalyst stability was also examined through reusability and leaching experiments and it is observed that the catalyst can be reused with no significant drop in its activity.
Co-reporter:O. Beyer;T. Homburg;M. Albat;N. Stock;U. Lüning
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 17) pp:8870-8876
Publication Date(Web):2017/08/21
DOI:10.1039/C7NJ01697B
Ten aromatic building blocks (8–11, 23–28) containing phosphonic and sulfonic acid groups within one molecule were synthesized. Twofold nucleophilic substitution starting from 1,2,4,5-tetrakis(bromomethyl)benzene (1) followed by hydrolysis gave building blocks 8–11. To obtain building blocks 23–28, the respective bromobenzenesulfonic acids 13, 16, 18–20 and 22 had to be synthesized first. Palladium-catalysed cross coupling with triethylphosphite followed by hydrolysis gave the desired building blocks with phosphonic and sulfonic acid groups. Building block 9 was successfully used as a linker for the synthesis of a new La-based CP with the composition [La2(H2L)1.5(H2O)4].
Co-reporter:M. Köppen;O. Beyer;S. Wuttke;U. Lüning;N. Stock
Dalton Transactions 2017 vol. 46(Issue 26) pp:8658-8663
Publication Date(Web):2017/07/04
DOI:10.1039/C7DT01744H
Two new bismuth metal–organic frameworks (Bi-MOFs) were discovered using high throughput experiments employing bismuth(III) nitrate pentahydrate and triazine-2,4,6-triyl-tribenzoic acid (H3TATB). The reaction was carried out for long reaction times (∼5 d) in a water/DMF-mixture and resulted in the formation of [Bi2(O)(OH)(TATB)]·H2O (denoted as CAU-35). By switching to short reaction times and a methanol/DMF-mixture as the solvent, an analogue of CAU-7-BTB with the composition [Bi(TATB)]·DMF·6H2O (denoted as CAU-7-TATB) was obtained. The use of the amino-functionalised H3TATB linker (H3TATB-NH2) resulted in the formation of a functionalised porous Bi-MOF with the composition [Bi(TATB-NH2)]·5H2O·0.5DMF (CAU-7-TATB-NH2). The structures of CAU-35 and CAU-7-TATB were successfully solved and refined from the PXRD data. CAU-7-TATB-NH2 was post-synthetically modified using anhydrides (acetic anhydride and valeric anhydride), cyclic anhydrides (succinic anhydride and phthalic anhydride), and 1,3-propane sultone. The degree of conversion ranged from 33% to 79%.
Co-reporter:Martin Krüger;Martin Albat;A. Ken Inge
CrystEngComm (1999-Present) 2017 vol. 19(Issue 31) pp:4622-4628
Publication Date(Web):2017/08/07
DOI:10.1039/C7CE01067B
Three new In-MOFs with –NH2 and/or –NO2 functionalities are reported using 2-amino- (H2BDC-NH2), 2-nitro- (H2BDC-NO2) and 2-amino-5-nitroterephthalic acid (H2BDC-NH2/NO2). Their structures were determined from single crystal X-ray diffraction data. The structure of the first In-MOF of composition [In(BDC-NH3)(BDC-NH2)]·1.6DMF·1.9H2O (In-BDC-NH2; DMF is dimethylformamide; the space group is P6222, a = b = 14.738(2) Å and c = 12.257(3) Å) is built up by two interpenetrating nets of InO8 polyhedra interconnected by BDC-NH22− ions to form a framework with qtz topology. Charge balance is accomplished by partial protonation of the amino group, which was confirmed by IR spectroscopy. The interpenetration leads to a decrease of the pore dimension (4.4 Å in diameter). Thermogravimetric analysis revealed stability up to 300 °C. Replacement of H2BDC-NH2 by H2BDC-NO2 in the reaction mixture led to the isoreticular MOF containing no –NO2 groups but exclusively un- and amino-functionalized linkers. Hence an indium mediated reduction of the H2BDC-NO2 linker molecule during solvothermal synthesis has occurred. The use of H2BDC-NH2/NO2 under exactly the same reaction conditions did not result in the formation of a MOF, but by changing the synthesis parameters, a new –NH2/–NO2 bifunctionalised In-MOF of composition (DMA)2[In3(μ3-O)(BDC-NH2/NO2)4.5]·DMF (DMA is dimethylammonium), denoted In-BDC-NH2/NO2, was obtained. The crystal morphology can be altered from cubic to truncated octahedral crystals by varying the DMF/ethanol volume ratio during synthesis. The compound crystallises in the cubic space group I3m, a = 24.8947(1) Å, and the framework contains trinuclear {In3(μ3-O)} clusters which are interlinked by the BDC-NH2/NO22− ions to form super-tetrahedra. Four face-sharing super-tetrahedra form ultra-tetrahedra which are connected to form the final cubic framework with an ncb topology and isolated inaccessible pores.
Co-reporter:Helge Reinsch;Jannik Benecke;Martin Etter;Niclas Heidenreich
Dalton Transactions 2017 vol. 46(Issue 5) pp:1397-1405
Publication Date(Web):2017/01/31
DOI:10.1039/C6DT03998G
The intercalation of different pyrazines (pyrazine, methylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, trimethylpyrazine and tetramethylpyrazine) into the trans-1,4-cyclohexanedicarboxylate (CDC2−) based Al-MOF [Al(OH)(CDC)], denoted as CAU-13, was investigated. The adsorption of the guest molecules into the flexible MOF was carried out from an aqueous solution or via vapour phase adsorption, starting with the hydrated narrow-pore form of the framework [Al(OH)(O2C-C6H10-CO2)]·H2O (CAU-13-np). The obtained host–guest systems were characterised by thermogravimetry and vibrational spectroscopy and their crystal structures were elucidated using powder X-ray diffraction (PXRD) data. The crystal structures indicate that guest molecules forming hydrogen-bonds with the host framework (pyrazine, methylpyrazine and 2,5-dimethylpyrazine) induce a slight opening of the channels, resulting in a semi-open framework conformation (CAU-13-so). For the bulkier guests 2,3-dimethylpyrazine, trimethylpyrazine and tetramethylpyrazine, only van der Waals interactions can be observed between the host and the guest molecules and a large pore conformation is observed (CAU-13-lp). We carried out in situ PXRD studies using synchrotron radiation during the adsorption of the respective guest molecules from aqueous solutions with various concentrations and at different temperatures. In general, stronger host–guest interactions required milder adsorption conditions while harsher conditions nevertheless accelerated the conversion. The kinetic parameters for the intercalation of pyrazine indicate that the rate limiting step differs, depending on the intercalation temperature.
Co-reporter:A. Ken Inge; Milan Köppen; Jie Su; Mark Feyand; Hongyi Xu; Xiaodong Zou; Michael O’Keeffe
Journal of the American Chemical Society 2016 Volume 138(Issue 6) pp:1970-1976
Publication Date(Web):January 21, 2016
DOI:10.1021/jacs.5b12484
A bismuth-based metal–organic framework (MOF), [Bi(BTC)(H2O)]·2H2O·MeOH denoted CAU-17, was synthesized and found to have an exceptionally complicated structure with helical Bi–O rods cross-linked by 1,3,5-benzenetricarboxylate (BTC3–) ligands. Five crystallographically independent 1D channels including two hexagonal channels, two rectangular channels, and one triangular channel have accessible diameters of 9.6, 9.6, 3.6, 3.6, and 3.4 Å, respectively. The structure is further complicated by twinning. Rod-incorporated MOF structures typically have underlying nets with only one unique node and three or four unique edges. In contrast, topological analysis of CAU-17 revealed unprecedented complexity for a MOF structure with 54 unique nodes and 135 edges. The complexity originates from the rod packing and the rods themselves, which are related to aperiodic helices.
Co-reporter:Selda Halis, A. Ken Inge, Niklas Dehning, Thomas Weyrich, Helge Reinsch, and Norbert Stock
Inorganic Chemistry 2016 Volume 55(Issue 15) pp:7425-7431
Publication Date(Web):July 18, 2016
DOI:10.1021/acs.inorgchem.6b00661
Two new dihydroxybenzoquinone-based metal–organic frameworks, ((CH3)2NH2)3[Al4(L1)3(L1•)3]·3DMF (1, denoted CAU-20) and ((CH3)2NH2)3[Al4(L2)3(L2•)3]·9DMF (2, denoted CAU-20-Cl2), were synthesized at 120 °C in DMF using 2,5-dihydroxy-p-benzoquinone ((C6H2(OH)2(O)2), H2L1) and 2,5-dichloro-3,6-dihydroxy-p-benzoquinone ((C6Cl2(OH)2(O)2), H2L2), respectively. Compared to other Al-MOFs, which contain carboxylate or phosphonate groups that connect the metal sites, in 1 and 2 the Al3+ are coordinated by oxido groups. The metal ions are octahedrally surrounded by oxygen atoms of the deprotonated linker molecules to generate honeycomb layers with a metal to linker ratio of Al: L1/L2 = 2:3. The layers contain L12– and L22– ions as well as linker radical ions L1•3– and L2•3– in a molar ratio of 1 to 1. The presence of radical ions was confirmed by EPR and UV–vis-spectroscopic measurements, and the composition was determined from a combination of PXRD, 1H NMR, TG, and elemental analyses. Charge balance is accomplished through intercalation of (CH3)2NH2+ ions which are formed by partial hydrolysis of DMF. In the structures of 1 and 2 the eclipsed layers are AA and ABAB stacked, respectively, and one-dimensional hexagonal channels with diameters of ca. 9 and 6 Å are formed. Both compounds exhibit permanent porosity and have specific surface areas of 1440 and 1430 m2 g–1, respectively.
Co-reporter:Timo Rhauderwiek, Steve Waitschat, Stefan Wuttke, Helge Reinsch, Thomas Bein, and Norbert Stock
Inorganic Chemistry 2016 Volume 55(Issue 11) pp:5312-5319
Publication Date(Web):May 20, 2016
DOI:10.1021/acs.inorgchem.6b00221
Two porphyrin-based metal–organic frameworks (MOFs) containing gallium or indium, [Ga2(OH)2(H2TCPP)]·3DMF·3H2O (Ga-PMOF) and [In2(OH)2(H2TCPP)]·3DMF·4H2O (In-PMOF) (H6TCPP = 4-tetracarboxyphenylporphyrin), were discovered using high-throughput methods. The structure was refined by the Rietveld-method starting from the structure model of Al-PMOF, [Al2(OH)2(H2TCPP)]. The new PMOFs exhibit BET surface areas between 1150 and 1400 m2 g–1 and are also porous toward CO2 (Ga-PMOF, 15.2 wt %; In-PMOF, 12.9 wt %). They are thermally stable in air up to 330 °C, but show limited chemical stabilities toward acids and bases. In order to achieve size control, different synthesis routes were investigated, i.e., batch synthesis at different temperatures (yield: In-PMOF-bs-th 96%, Ga-PMOF-bs-th 87%), ultrasound-assisted synthesis (yield: In-PMOF-bs-us 85%), and continuous-flow synthesis (yield: Ga-PMOF-cf 71%). By using these different methods we could control the nucleation rate and the crystal size. The crystal sizes were found to vary about 60 to 160 nm and 70 to 130 nm for Ga- and In-PMOF, respectively, which was proven by dynamic light scattering (DLS), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements.
Co-reporter:Helge Reinsch, Renjith S. Pillai, Renée Siegel, Jürgen Senker, Alexandra Lieb, Guillaume Maurin and Norbert Stock
Dalton Transactions 2016 vol. 45(Issue 10) pp:4179-4186
Publication Date(Web):16 Oct 2015
DOI:10.1039/C5DT03510D
The new aluminium based metal–organic framework [Al(OH)(O2C–C4H8–CO2)]·H2O denoted as Al-MIL-53-ADP-lp (lp stands for large pore) was synthesised under solvothermal conditions. This solid is an analogue of the archetypical aluminium terephthalate Al-MIL-53 based on the aliphatic single-chain linker molecule adipic acid (H2ADP, hexanedioic acid). In contrast to its aromatic counterparts, Al-MIL-53-ADP exhibits a structural breathing behaviour solely upon dehydration/rehydration. The crystal structure of the anhydrous compound denoted as Al-MIL-53-ADP-np (np stands for narrow pore) was determined by a combination of forcefield-based computations and Rietveld refinement of the powder X-ray diffraction data while the structure of the hydrated form Al-MIL-53-ADP-lp was derived computationally by a combination of force field based methods and Density Functional Theory calculations. Both structures were further supported by 1H, 13C and 27Al high-resolution NMR MAS 1D data coupled again with simulations. Al-MIL-53-ADP was further characterised by means of vibrational spectroscopy, elemental analysis, thermogravimetry and water vapour sorption.
Co-reporter:Martin Lammert, Michael T. Wharmby, Simon Smolders, Bart Bueken, Alexandra Lieb, Kirill A. Lomachenko, Dirk De Vos and Norbert Stock
Chemical Communications 2015 vol. 51(Issue 63) pp:12578-12581
Publication Date(Web):02 Jul 2015
DOI:10.1039/C5CC02606G
A series of nine Ce(IV)-based metal organic frameworks with the UiO-66 structure containing linker molecules of different sizes and functionalities were obtained under mild synthesis conditions and short reaction times. Thermal and chemical stabilities were determined and a Ce-UiO-66-BDC/TEMPO system was successfully employed for the aerobic oxidation of benzyl alcohol.
Co-reporter:Nele Reimer, Helge Reinsch, A. Ken Inge, and Norbert Stock
Inorganic Chemistry 2015 Volume 54(Issue 2) pp:492-501
Publication Date(Web):December 24, 2014
DOI:10.1021/ic502242j
A new sulfone-functionalized metal–organic framework [Al(OH)(SDBA)]·0.25DMF, denoted CAU-11, was synthesized using a V-shaped linker molecule 4,4′-sulfonyldibenzoic acid (H2SDBA). The crystal structure was solved from synchrotron X-ray powder diffraction data. Chains of trans corner-sharing AlO6 octahedra are interconnected by the carboxylate groups to form layers (ABAB stacking). Within the layers, hydrophobic lozenge-shaped pores with a diameter of 6.4 × 7.1 Å2 are present inducing permanent porosity (aBET = 350 m2 g–1 and Vmicro = 0.17 cm3 g–1). With the application of HT-methods (HT = high throughput), the isoreticular carboxylate functionalized compound [Al(OH)(H2DPSTC)]·0.5H2O (CAU-11-COOH) was synthesized using the linker molecule 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DPSDA), which hydrolyzes under the reaction conditions. Due to the additional noncoordinating carboxylic acid groups the pores are hydrophilic. Changing the molar ratio of Al3+ to linker lead to the discovery of a second new compound [Al2(OH)2(DPSTC)(H2O)2]·0.5H2O (CAU-12). In CAU-12 the linker molecule is fully deprotonated which leads to different connectivity compared to the structure of CAU-11-COOH. Thermal activation of CAU-12 leads to dehydration and transformation of the structure to [Al2(OH)2(DPSTC)]·nH2O (CAU-12-dehy). Coordinated water molecules were removed, and the coordination site is replaced by the previously noncoordinating O atom of the adjacent carboxylate group. The SO2-groups point into the pores resulting in a highly hydrophobic three-dimensional framework. The compounds exhibit high thermal stability in air at least up to 420 °C. Synthesis of CAU-11 can be easily scaled up in very high yields (98%).
Co-reporter:N. Hermer and N. Stock
Dalton Transactions 2015 vol. 44(Issue 8) pp:3720-3723
Publication Date(Web):27 Jan 2015
DOI:10.1039/C4DT03698K
High throughput methods were employed in the discovery of [Cu3(PPT)(H2O)3]·10H2O (denoted CAU-14). The structure contains one-dimensional channels with a diameter of 9.4 Å. Thermal activation leads to the formation of uncoordinated metal sites and a high water uptake of 39.1 wt% was found.
Co-reporter:Steve Waitschat, Michael T. Wharmby and Norbert Stock
Dalton Transactions 2015 vol. 44(Issue 24) pp:11235-11240
Publication Date(Web):15 May 2015
DOI:10.1039/C5DT01100K
A continuous flow reactor was developed for the synthesis of porous metal–organic frameworks (MOFs) under mild reaction conditions. Commodity hardware was used to assemble the device, giving it a great degree of flexibility in its configuration. The use of paraffin to encapsulate reactions and also ultrasonic treatment were employed to prevent clogging of the reactor. Reactor design was optimised through studies of the synthesis of zirconium carboxylate framework UiO-66. Synthesis of the aluminium carboxylate CAU-13 was also performed, to demonstrate the versatility of the device. Finally the reactor was used to synthesise a new cadmium phosphonate framework, bearing the STA-12 network.
Co-reporter:Selda Halis, Nele Reimer, Arne Klinkebiel, Ulrich Lüning, Norbert Stock
Microporous and Mesoporous Materials 2015 Volume 216() pp:13-19
Publication Date(Web):1 November 2015
DOI:10.1016/j.micromeso.2015.01.030
•Isoreticular MOFs were obtained using linkers with nitro, amino or sulfone groups.•Naphthyl- and biphenyldicarboxylic acid derivatives were used as linker molecules.•The permanently porous Al-MOFs are thermally stable at least up to 340 °C in air.•The presence of the sulfone groups leads to an increase of CO2 adsorption capacity.Al-based metal-organic framework (MOF) compounds containing nitro- and amino-substituted and sulfone-bridged groups were synthesized: [Al(OH)(NDC-(NO2)2)] (1), [Al(OH)(BPDC-NO2)] (2), [Al(OH)(BPDC-NH2)] (3) and [Al(OH)(BPDC-SO2)] (4), which are analogs of MIL-69/DUT-4 ([Al(OH)(NDC)]) or DUT-5 ([Al(OH)(BPDC)]) (NDC = 2,6-naphthalenedicarboxylate, BPDC = 4,4’-biphenyldicarboxylate). The compounds were synthesized under solvothermal conditions employing microwave-assisted heating and characterized by powder X-ray diffraction, thermogravimetric analysis and gas sorption measurements. They exhibit permanent porosity and are accessible to carbon dioxide, hydrogen and methane but do not show any framework flexibility like MIL-53. All compounds are highly stable as confirmed by temperature-dependent powder X-ray diffraction measurements (TD-PXRD) and framework decomposition takes place between 340 °C and 420 °C.
Co-reporter:Martin Krüger, Renée Siegel, Anna Dreischarf, Helge Reinsch, Jürgen Senker, Norbert Stock
Microporous and Mesoporous Materials 2015 Volume 216() pp:27-35
Publication Date(Web):1 November 2015
DOI:10.1016/j.micromeso.2015.04.023
•An isoreticular Al-MOF was obtained using an extended linker molecule.•The permanently porous Al-MOF is thermally stable at least up to 480 °C in air.•Each carboxylate group of the tetratopic linker coordinates Al octahedra bidentately.•Distribution of 27Al quadrupolar coupling constants reflects framework flexibility.High-throughput methods were employed in the discovery and synthesis optimization of the new microcrystalline metal-organic framework (MOF) [Al2(OH)2(TCPB)] · 2 DMF (denoted CAU-9as), which contains the tetratopic linker ion 1,2,4,5-tetrakis-(4-carboxylatophenyl)-benzene (TCPB4−). The compound is obtained under solvothermal reaction conditions and activation at 150 °C leads to the removal of the guest molecules (CAU-9act). Detailed characterization was carried out by FT-IR and NMR spectroscopy, thermogravimetric analysis, gas sorption measurements and X-ray powder diffraction. CAU-9act crystallizes in an orthorhombic unit cell (space group Cmmm) with the cell parameters: a = 31.562(4), b = 6.642(7), c = 10.6612(7) Å. Modeling by force field calculations in combination with Rietveld refinement was used to determine the structure of CAU-9. The content of the asymmetric unit was corroborated based on NMR crystallographic strategies evaluating high-resolution 1H, 13C and 27Al MAS NMR spectra. The structure of CAU-9 is isoreticular to the one of MIL-118B [Al2(OH)2(BTEC)] (BTEC = 1,2,4,5-benzenetetracarboxylate) and Al-PMOF [Al2(OH)2(TCPP)] (TCPP = meso-tetra(4-carboxylato-phenyl)porphyrin). According to the temperature dependent PXRD measurements and the thermogravimetric analysis, it is stable up to 480 °C in air. The nitrogen sorption measurement at 77 K has given a Brunauer–Emmett–Teller (BET) surface area of 1118 m2 g−1 and a micropore volume of 0.45 cm3 g−1. In contrast to MIL-118 no rearrangement of the carboxylate groups from a mono-to bidentate coordination mode was observed upon activation.
Co-reporter:Helge Reinsch
The Journal of Physical Chemistry C 2015 Volume 119(Issue 47) pp:26401-26408
Publication Date(Web):November 1, 2015
DOI:10.1021/acs.jpcc.5b03138
The metal–organic framework CAU-10-NO2 [Al(OH)BDC-NO2] (CAU stands for Christian-Albrechts-University; H2BDC-NO2 is 5-nitroisophthalic acid) was observed to exhibit unexpected photochemical reactivity. Upon irradiation of the MOF with UV light with a wavelength of 365 nm (or with sunlight), guest molecules inside the pore system of the MOF can be oxidized and stable radicals are formed from the organic linker molecules. The reactivity toward different alcohols was studied by UV/vis spectroscopy and EPR spectroscopy. The amount of generated radicals depends on the size of the solvent molecules; however, as an exception, methanol shows a much lower reactivity than ethanol. DFT calculations were carried out to gain insights into these photochemical reactions. The results indicate that the nitro group is reduced to form a nitroso moiety. This was confirmed by means of NMR spectroscopy. The exact nature of the radical could not be revealed, but the results indicate that it could be a further reduced anionic nitroso radical. Methanol and ethanol can be distinguished using this photochemical reaction simply by the coloring of the irradiated MOF. Such a property is characteristic for a sensor; therefore, a synthesis procedure was developed to implement the MOF into a device by which the compound was directly grown onto gold substrates.
Co-reporter:Nele Reimer;Bart Bueken;Sebastian Leubner;Christopher Seidler; Michael Wark; Dirk DeVos; Norbert Stock
Chemistry - A European Journal 2015 Volume 21( Issue 35) pp:12517-12524
Publication Date(Web):
DOI:10.1002/chem.201501502
Abstract
Ten mixed-linker metal–organic frameworks [Al(OH)(m-BDC-X)1−y(m-BDC-SO3H)y] (H2BDC=1,3-benzenedicarboxylic acid; X=H, NO2, OH) exhibiting the CAU-10-type structure were synthesized. The compounds can be grouped into three series according to the combination of ligands employed. The three series of compounds were obtained by employing different ratios of m-H2BDC-X and m-H2BDC-SO3Li. The resulting compounds, which are denoted CAU-10-H/Sx, -N/Sx and -O/Sx, show exceptionally high thermal stability for sulfonated materials of up to 350 °C. Detailed characterization with special focus on polarity and acidity was performed, and the impact of the additional SO3H groups is clearly demonstrated by changes in the sorption affinities/capacities towards several gases and water vapor. In addition, selected samples were evaluated for proton conductivity and as catalysts for the gas-phase dehydration of ethanol to ethylene. While only very low proton conductivities were observed, a pronounced increase in catalytic activity was achieved. Although reactions were performed at temperatures of 250 and 300 °C for more than 40 h, no desulfonation and no loss of crystallinity were observed, and stable ethanol conversion resulted. This demonstrates the high stability of this material.
Co-reporter:Felicitas Niekiel, Jeroen Lannoeye, Helge Reinsch, Alexis S. Munn, Andreas Heerwig, Ivo Zizak, Stefan Kaskel, Richard I. Walton, Dirk de Vos, Philip Llewellyn, Alexandra Lieb, Guillaume Maurin, and Norbert Stock
Inorganic Chemistry 2014 Volume 53(Issue 9) pp:4610-4620
Publication Date(Web):April 10, 2014
DOI:10.1021/ic500288w
The Al-MOF CAU-13 ([Al(OH)(trans-CDC)]; trans-H2CDC = trans-1,4-cyclohexanedicarboxylic acid) is structurally related to the MIL-53 compounds that are well-known for their “breathing” behavior, i.e., the framework flexibility upon external stimuli such as the presence of adsorbate molecules. The adsorption properties of CAU-13 were investigated in detail. The sorption isotherms of N2, H2, CH4, CO, CO2, and water were recorded, and the adsorption enthalpies for the gases were determined by microcalorimetry. The structural changes upon adsorption of CO2 were followed with in situ synchrotron powder X-ray diffraction (PXRD). The patterns were analyzed by parametric unit cell refinement, and the preferential arrangement of the CO2 molecules was modeled by density functional theory calculations. The adsorption and separation of mixtures of o-, m-, and p-xylene from mesitylene showed a preferred adsorption of o-xylene. The structures of o/m/p-xylene-loaded CAU-13 were determined from PXRD data. The adsorption of xylene isomers induces a larger pore opening than that in the thermal activation of CAU-13. In the crystal structure of the activated sample CAU-13(empty pore), half of the linkers adopt the a,a confirmation and the other half the e,e conformation, and the presence of a,a-CDC2– ions hampers the structural flexibility of CAU-13. However, after the adsorption of xylene, all linkers are present in the e,e conformation, allowing for a wider pore opening by this new type of “breathing”.
Co-reporter:Lars-Hendrik Schilling and Norbert Stock
Dalton Transactions 2014 vol. 43(Issue 2) pp:414-422
Publication Date(Web):31 Oct 2013
DOI:10.1039/C3DT52576G
High-throughput reactions of aqueous solutions of 4-(phosphonomethyl)benzoic acid (H3PMBC) with metal salts were carried out using, for the first time, ultrasonication as well as the previously described conventional heating. On screening the influence of 12 divalent metal ions, two new compounds ([Ca(H2O)2(H2PMBC)2] and [Ni(H2O)4(H2PMBC)2]) were discovered. Their formation fields were established by systematically studying the systems Ni2+ or Ca2+/H3PMBC/KOH. Both compounds crystallise in the space group P ([Ca(H2O)2(H2PMBC)2]: a = 4.6806(9) Å, b = 6.1340(12) Å, c = 17.932(4) Å, α = 83.84(3)°, β = 89.03(3)°, γ = 85.65(3)°; [Ni(H2O)4(H2PMBC)2]: a = 4.7713(10) Å, b = 6.8621(14) Å, c = 16.598(3) Å, α = 83.42(3)°, β = 89.71(3)°, γ = 83.50(3)°) and contain MO6-octahedra linked to form chains by hydrogen bonded (H2PMBC−)2-dimers formed between the carboxylate groups. The formation of [Ni(H2O)4(H2PMBC)2] was studied by in situ EDXRD and in situ IR spectroscopy. The increased formation rate of [Ni(H2O)4(H2PMBC)2] under ultrasonic irradiation as compared to conventional heating could be unequivocally attributed to the faster dissolution of the ligand H3PMBC.
Co-reporter:Felicitas Niekiel and Norbert Stock
Crystal Growth & Design 2014 Volume 14(Issue 2) pp:599-606
Publication Date(Web):December 16, 2013
DOI:10.1021/cg401459a
The formation of calcium etidronates was investigated employing high-throughput ultrasonic synthesis. In the study of the system CaCl2/H2O3P-C(OH)(CH3)-PO3H2/H2O/KOH three new crystalline products were obtained in dependence of the deprotonation degree of the bisphosphonic acid HEDP (1-hydroxyethylidene-1,1-diphosphonic acid, H2O3P-C(OH)(CH3)-PO3H2) and the sonication time. In a large region of the parameter space and at short reaction times [Ca(HO3P-C(OH)(CH3)-PO3H)(H2O)]·2.5H2O (1) forms. At higher pH [KCa(HO3P-C(OH)(CH3)-PO3)(H2O)]·H2O (2) containing the asymmetrically deprotonated HO3P-C(OH)(CH3)-PO33– ion and [K2Ca(O3P-C(OH)(CH3)-PO3)(H2O)6] (3) with the fully deprotonated ligand are obtained. The crystal structures of 1 and 2 were solved and refined from X-ray powder diffraction data. The thermal decomposition of the compounds was investigated. If exposed to moderate temperatures 1.5 water molecules per formula unit are removed from the crystal structure of 1 and the pseudopolymorphic compound [Ca(HO3P-C(OH)(CH3)-PO3H)(H2O)2] is formed [Uchtman J. Phys. Chem. 1972, 76, 1304−1310].
Co-reporter:Michael T. Wharmby, Malte Snoyek, Timo Rhauderwiek, Knut Ritter, and Norbert Stock
Crystal Growth & Design 2014 Volume 14(Issue 10) pp:5310-5317
Publication Date(Web):August 20, 2014
DOI:10.1021/cg501189n
Systematic investigation of the reactions of the system AlCl3·6H2O/pyridine-2,4,6-tricarboxylic acid (H3PTC)/pyridine in water yielded two new compounds, both containing the dimeric {AlPTC(μ-OH)(H2O)}22– unit. With long reaction times, the framework compound [Al(μ-OH){AlPTC(μ-OH)(H2O)}2]·2H2O (CAU-16, compound 1) is obtained, the first example of a framework compound with a metal–organic cluster linker, and bearing the MIL-53 network. Although the compound does not breathe, as other MIL-53 compounds do, it has a maximum uptake of CO2 of 1.76(2) mmol g–1 at 196 K. With shorter reaction times, the molecular compound {Al(HPTC)(μ-OH)(H2O)}2 (2) was prepared, leading to the proposal of a crystallization scheme for the Al3+-pyridine-2,4,6,-tricarboxylic acid system. To determine whether further framework compounds bearing hybrid metal cluster linkers could be prepared, systematic high-throughput investigations of pyridine-2,4,6-tricarboxylic acid in water with Ga3+ and In3+ were undertaken. These yielded two chain-type compounds, GaPTC(H2O)2 (3) and InPTC(H2O)2 (4), with different coordination chemistries. Optimized syntheses for compounds 1, 2, and 4 are reported.
Co-reporter:Lars-Hendrik Schilling;Felicitas Niekiel;Dr. Norbert Stock;Dr. Bernd Hartke
ChemPlusChem 2014 Volume 79( Issue 6) pp:863-871
Publication Date(Web):
DOI:10.1002/cplu.201300407
Abstract
The local, deterministic optimisation algorithm BOBYQA (bound optimisation by quadratic approximation) was applied for the computer-assisted optimisation of inorganic–organic hybrid compounds. Four proof-of-concept studies were performed: 1) increasing the crystallinity and 2) inhibiting the crystallisation of [Ca(H2O)2(H2PMBC)2] (H2PMBC−=−HO3P-CH2-C4H6-COOH), 3) increasing the crystal size of [Bi(H2O)(BTC)] (BTC3−=benzene-1,3,5-tricarboxylate) and 4) tuning the particle sizes of [Al(OH)(CDC)]⋅x H2O (CDC2−=trans-1,4-cyclohexane dicarboxylate) to a desired value. The measurable quantities of crystallinity, crystal size and hydrodynamic diameter were used as the quality criteria for the optimisation, and the parameters of reaction time and temperature, molar ratios and overall concentration of the starting materials as well as the stirring rate were varied. The crystallinity of [Ca(H2O)2(H2PMBC)2] was increased in three optimisation steps by approximately 14 %, which was accompanied by an increase in crystal size by a factor of approximately 40. These crystals were suitable for structure determination from single-crystal X-ray diffraction data. The crystallisation of the same compound could be completely inhibited and clear solutions were obtained. The average crystal size of [Bi(H2O)(BTC)] was increased from (22.2±4.5) to (34.8±9.5) μm and the upper limit increased from 30.0 to 57.7 μm over the course of the optimisation. For the application in Bragg stacks, the variation of particle sizes of [Al(OH)(CDC)]⋅x H2O was studied. Although we aimed at a decrease to 100 nm, a lower limit of 460 nm and polydispersity index of 0.03 were accomplished. The convergence of the algorithm indicates that the optimisation progress is close to completion and the found value for the particle size is close to the lower limit in the system of the chosen parameters. These proofs-of-concept studies demonstrate the potential of optimisation algorithms like BOBYQA in synthesis optimisation experiments. At the same time, the convergence behaviour of the algorithm gives an indication of the progress of an optimisation.
Co-reporter:Ka-Kit Yee ; Nele Reimer ; Jie Liu ; Sum-Yin Cheng ; Shek-Man Yiu ; Jens Weber ; Norbert Stock ;Zhengtao Xu
Journal of the American Chemical Society 2013 Volume 135(Issue 21) pp:7795-7798
Publication Date(Web):May 7, 2013
DOI:10.1021/ja400212k
Free-standing, accessible thiol (−SH) functions have been installed in robust, porous coordination networks to provide wide-ranging reactivities and properties in the solid state. The frameworks were assembled by reacting ZrCl4 or AlCl3 with 2,5-dimercapto-1,4-benzenedicarboxylic acid (H2DMBD), which features the hard carboxyl and soft thiol functions. The resultant Zr-DMBD and Al-DMBD frameworks exhibit the UiO-66 and CAU-1 topologies, respectively, with the carboxyl bonded to the hard Zr(IV) or Al(III) center and the thiol groups decorating the pores. The thiol-laced Zr-DMBD crystals lower the Hg(II) concentration in water below 0.01 ppm and effectively take up Hg from the vapor phase. The Zr-DMBD solid also features a nearly white photoluminescence that is distinctly quenched after Hg uptake. The carboxyl/thiol combination thus illustrates the wider applicability of the hard-and-soft strategy for functional frameworks.
Co-reporter:Helge Reinsch, Monique A. van der Veen, Barbara Gil, Bartosz Marszalek, Thierry Verbiest, Dirk de Vos, and Norbert Stock
Chemistry of Materials 2013 Volume 25(Issue 1) pp:17
Publication Date(Web):November 28, 2012
DOI:10.1021/cm3025445
Employing high-throughput methods, the synthesis conditions for a series of six new MOFs based on aluminum ions and the V-shaped linker molecule 1,3-benzene dicarboxylic acid, denoted as CAU-10-X (CAU = Christian-Albrechts-University) with the sum formula [Al(OH)(C8H3O4X)]·solvent, were established (X = functional group in 5-position of the aromatic ring; X = H (1), CH3 (2), OCH3 (3) NO2 (4), NH2 (5), or OH (6)). Because of the absence of macroscopic crystals, the obtained compounds were structurally characterized employing XRPD-methods. The crystal structures of 1, 2, and 3 were refined using Rietveld methods. Although the described MOFs are isoreticular, they crystallize in several, sometimes noncentrosymmetric space groups (1, 4, 6), because of slight structural changes induced by the functionalization. These space groups were confirmed with second-harmonic generation measurements. All compounds are highly stable as confirmed by temperature-dependent XRPD and IR experiments and decompose at temperatures above 350 °C. The stabilities of all compounds in aqueous solutions of varying pH were confirmed by XRPD measurements and their sorption properties toward nitrogen, hydrogen, carbon dioxide, and water vapor at low pressures are reported. A drastic influence of the functional group on affinity, capacity, and accessibility of the pores for these gases is observed. These properties depend on the polarity and size of the functional group as well as on subtle structural differences between the CAU-10-X compounds.Keywords: aluminum carboxylates; isoreticular chemistry; metal−organic frameworks; nonlinear optical properties; porous materials;
Co-reporter:Helge Reinsch, Martin Krüger, Jerome Marrot, and Norbert Stock
Inorganic Chemistry 2013 Volume 52(Issue 4) pp:1854-1859
Publication Date(Web):January 28, 2013
DOI:10.1021/ic301961q
Based on the V-shaped linker molecule 4,4′-benzophenonedicarboxylic acid, the new carbonyl-functionalized metal–organic framework (MOF) [Al(OH)(O2C-C6H4-CO-C6H4-CO2)], denoted as CAU-8, was discovered employing high-throughput methods. The compound is obtained from 4,4′-benzophenonedicarboxylic acid, Al2(SO4)3·18H2O in a mixture of N,N-dimethylformamide (DMF) and water under solvothermal conditions. The structure was determined from single-crystal X-ray diffraction data (I41/a, a = b = 13.0625(5), c = 52.565(2) Å). The framework is based on infinite inorganic building units of trans-connected, corner-sharing AlO6-polyhedra. Parallel Al–O-chains are arranged in layers perpendicular to [001]. Within a layer an interchain distance of ∼1.1 nm is observed. The orientation of the Al–O-chains within neighboring layers is perpendicular to each other, along [100] and [010], respectively, and an ABCDA stacking of these layers is observed. The interconnection of these orthogonally oriented chains by the V-shaped dicarboxylate ions results in the formation a three-dimensional framework structure containing one-dimensional channels with a diameter of about 8 Å. The pore walls are lined by the keto-groups. CAU-8 was thoroughly characterized by X-ray powder diffraction (XRPD), thermogravimetric measurements, IR- and Raman-spectroscopy, elemental analysis, and gas sorption experiments using N2 and H2 as adsorptives. CAU-8 is stable up to 350 °C in air and exhibits a moderate porosity with a specific surface area of SBET = 600 m2/g and a micropore volume of 0.23 cm3/g. Moreover, a detailed topological analysis of the framework was carried out, and an approach for the topological analysis of MOFs based on infinite 1-periodic building units is proposed.
Co-reporter:Felicitas Niekiel, Maximilian Ackermann, Paul Guerrier, André Rothkirch, and Norbert Stock
Inorganic Chemistry 2013 Volume 52(Issue 15) pp:8699-8705
Publication Date(Web):July 17, 2013
DOI:10.1021/ic400825b
The system AlCl3·6H2O/cis-H2CDC/trans-H2CDC/solvent was systematically investigated with high-throughput methods to study the influence of the two 1,4-cyclohexanedicarboxylate isomers (cis- and trans-H2CDC) as flexible aliphatic linker molecules on the formation of new crystalline compounds. Using the cis-isomer, the layered inorganic–organic hybrid compound [Al(OH)(cis-CDC)] (1) is formed. The use of trans-H2CDC leads to the microporous MOF [Al(OH)(trans-CDC)]·H2O (2) denoted CAU-13. Its framework is related to the well-known MIL-53, which was previously described for trivalent cations and rigid terephthalate linker molecules. The crystal structures of 1 and 2 were derived from powder X-ray diffraction data. Temperature-dependent in situ energy dispersive X-ray diffraction (EDXRD) experiments for the synthesis of 2 were carried out at HASYLAB, DESY, Hamburg. The kinetic analysis, applying the Gualtieri model to the experimental data, revealed Arrhenius activation energies of 76 kJ/mol for both the nucleation and the growth process. These values do not differ much from the activation energies reported for MOFs with aromatic rigid linker molecules.
Co-reporter:Martin Lammert, Stephan Bernt, Frederik Vermoortele, Dirk E. De Vos, and Norbert Stock
Inorganic Chemistry 2013 Volume 52(Issue 15) pp:8521-8528
Publication Date(Web):July 5, 2013
DOI:10.1021/ic4005328
New single- and mixed-linker Cr-MIL-101 derivatives bearing different functional groups have been synthesized. The influence of the reaction parameters, such as metal source (CrO3, CrCl3, and Cr(NO3)3·9H2O) or linker composition, on product formation have been investigated using high-throughput methods. Highly crystalline Cr-MIL-101 materials were obtained with CrCl3 as the metal source with either 2-bromoterephthalic (TA-Br) or 2-nitroterephthalic (TA-NO2) acid as one of the mixed-linker components. On the basis of these results, numerous new mixed-linker Cr-MIL-101 derivatives containing -NH2, -NO2, -H, -SO3H, -Br, -OH, -CH3, and -COOH have been synthesized. The use of TA-NH2 and TA-OH were shown, under the same reaction conditions, to lead to decarboxylation and the formation of 3-amino- and 3-hydroxybenzoic acid, respectively. Furthermore, we were also able to directly synthesize single-linker Cr-MIL-101-X derivatives with X = F, Cl, Br, CH3. Postsynthetic modification was used to selectively reduce the mixed-linker compound Cr-MIL-101-Br-NO2 to Cr-MIL-101-Br-NH2. To establish the successful incorporation of the linker molecules and possible decomposition of certain starting materials, 1H NMR spectra of dissolved reaction products were recorded.
Co-reporter:Mark Feyand, Christopher F. Seidler, Carsten Deiter, Andre Rothkirch, Alexandra Lieb, Michael Wark and Norbert Stock
Dalton Transactions 2013 vol. 42(Issue 24) pp:8761-8770
Publication Date(Web):12 Apr 2013
DOI:10.1039/C3DT50413A
A systematic study was carried out to investigate the influence of linker geometry, metal ionic radius as well as the nature of the counter ions on the structure formation of metal tetraphosphonates. Two tetraphosphonic acids p- and m-(H2O3PCH2)2N-CH2-C6H4-CH2-N(CH2PO3H2)2, six metal ions (Ca2+, Mn2+, Co2+, Ni2+, Zn2+, and Cd2+) and two different counter ions (Cl− and NO3−) were employed using high throughput methods. Microwave (MW)-assisted heating led to the discovery of ten new metal-phosphonates which crystallize in three different crystal structures. The combination of direct methods and force field calculations allowed us to establish the crystal structures. The counter ion and the ionic radii of the metal ions have a profound influence on the crystallinity and the formed crystal structure. All compounds were characterized in detail by thermogravimetric analyses, IR spectroscopy and magnetic susceptibility measurements. The proton conductivity of two selected compounds is also reported.
Co-reporter:Helge Reinsch and Norbert Stock
CrystEngComm 2013 vol. 15(Issue 3) pp:544-550
Publication Date(Web):01 Nov 2012
DOI:10.1039/C2CE26436F
The synthesis and characterisation of the Mn-based analogue of the MIL-100 framework is reported. The title compound is synthesised from a methanolic solution of trimesic acid and manganese(II) nitrate in very short reaction times. During the reaction, the Mn2+ ions are oxidized in situ to Mn3+ ions. The obtained MOF was characterised by XRPD measurements, IR spectroscopy, thermogravimetric measurements and sorption experiments. To have a closer look at the crystallisation occurring after the in situ metal oxidation reaction that results in the formation of the title compound, in situ EDXRPD experiments under solvothermal conditions were carried out. These time-resolved measurements could be evaluated by two different kinetic models (by Avrami and Gualtieri) for crystallisation. The results indicate a two stage reaction process, which is dominated by different reaction mechanisms.
Co-reporter:Helge Reinsch, Steve Waitschat and Norbert Stock
Dalton Transactions 2013 vol. 42(Issue 14) pp:4840-4847
Publication Date(Web):14 Jan 2013
DOI:10.1039/C3DT32355B
The metal–organic framework compound [Al(OH)(BDC-Br)] (1) (BDC-Br2− = 5-bromo-1,3-benzenedicarboxylate) denoted CAU-10-Br was synthesised under solvothermal reaction conditions. Its structure was successfully refined by Rietveld methods. The framework is based on the connection of infinite helical chains of cis-corner-sharing AlO6-polyhedra via BDC-Br2− ions. Thus non-intersecting parallel channels are formed, each periodically varying in diameter between 1.1 and 6.6 Å. Nevertheless 1 adsorbs CO2 at 298 K, while it is non-porous towards H2 and N2 at 77 K. Employing high-throughput (HT) methods we identified synthesis conditions that lead to the formation of mixed-linker MOFs with CAU-10 topology. Starting with a molar ratio H2BDC:H2BDC-Br = 3:1 we established a synthesis procedure for the partially bromo-functionalised mixed-linker-MOF [Al(OH)(BDC)0.8(BDC-Br)0.2] (2) denoted as CAU-10-H/Br. Starting with a molar ratio H2BDC-NH2:H2BDC-NO2 = 1:1 the partially NO2- and NH2-functionalised mixed-linker MOF [Al(OH)(BDC-NO2)0.55(BDC-NH2)0.23(BDC-NHCHO)0.22] (3) denoted as CAU-10-NO2/NH2 was synthesised, in which the NH2-groups were found to be partially formylated. The partial bromo-functionalisation in CAU-10-H/Br (2) leads to a lower sorption capacity in comparison with the parent structure CAU-10-H, while the pore accessibility is comparable. The incorporation of NO2-, NH2- and NHCHO-groups in CAU-10-NO2/NH2 (3) does not only affect the accessibility of the pores for N2, but results also in an increased capacity for H2 and CO2 in comparison with the parent structure CAU-10-NO2. The reproducibility of the synthesis procedures was tested regarding the composition of the MOFs and the resulting gas sorption properties. In 2 a molar fraction of (BDC)2− = 80 ± 2% is found, while in 3 a molar fraction of (BDC-NO2)2− = 55 ± 2% is observed. Starting from the molar ratio H2BDC:H2BDC-CH3 = 1:1 mixed linker MOFs denoted as CAU-10-H/CH3 (4) were also obtained. In contrast to 2 and 3 the molar ratios of BDC2−/BDC-CH32− and especially the sorption properties differ substantially for every batch. The compounds were further characterised by X-ray powder diffraction, thermogravimetric/elemental analysis, NMR/Vis/IR-spectroscopy, and gas sorption measurements.
Co-reporter:Helge Reinsch, Norbert Stock
Microporous and Mesoporous Materials 2013 Volume 171() pp:156-165
Publication Date(Web):1 May 2013
DOI:10.1016/j.micromeso.2012.12.024
The use of high-throughput (HT) methods for the discovery of compounds as well as for the synthesis optimization in the field of porous aluminum MOFs is summarized. Taking the requirements of an industrial process into account, new synthesis procedures have been developed that demonstrate the versatility of the HT method. This is exemplified by the results that were obtained for the solvothermal system Al2(SO4)3·18H2O/polycarboxylic acid/H2O/DMF. Under rather mild reaction conditions, compared to the previously reported procedures, the Al-MOFs MIL-53-COOH, MIL-96, and MIL-120 were obtained employing 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, and 1,2,4,5-benzenetetracarboxylic acid, respectively. Applying the HT methodology combined with microwave(MW)-assisted heating, the synthesis procedure were rapidly established, optimized and scaled up. The obtained solids were characterized by X-ray powder diffraction (XRPD), elemental analysis, vibrational spectroscopy and nitrogen sorption measurements. The properties of these MOFs are discussed in comparison with literature values.Graphical abstractHighlights► High-throughput methods for the discovery of Al-MOFs are summarized. ► A three-step working scheme is presented that allows the facile synthesis of Al-MOFs. ► The workflow combines HT methods under conventional heating and MW-assisted heating. ► The mild conditions could allow the transfer from lab scale to industrial processes. ► The sorption properties of the Al-MOFs strongly depend on the synthesis conditions.
Co-reporter:Dr. Mark Fey;Milan Köppen;Dr. Gernot Friedrichs;Dr. Norbert Stock
Chemistry - A European Journal 2013 Volume 19( Issue 37) pp:12537-12546
Publication Date(Web):
DOI:10.1002/chem.201301139
Abstract
A systematic investigation of the systems Bi3+/carboxylic acid/HNO3 for the tri- and tetracarboxylic acids pyromellitic acid (H4Pyr), trimellitic acid (H3Tri) and trimesic acid (H3BTC) acid led to the discovery of five new bismuth carboxylates. Structural characterisation allowed the influence of the linker geometry and the Bi3+:linker molar ratio in the starting solution on the crystal structure to be determined. The crystallisation of three selected compounds was investigated by in situ energy-dispersive X-ray diffraction. Three new crystalline intermediates were observed within minutes, and two of them could be isolated by quenching of the reaction mixture. Their crystal structures were determined from laboratory and synchrotron X-ray powder diffraction data and allowed a possible reaction pathway to be established. In depth characterisation of the luminescence properties of the three bismuth pyromellate compounds was carried out. Fluorescence and phosphorescence could be assigned to (mainly) ligand- and metal-based transitions. The polymorphs of Bi(HPyr) exhibit different luminescence properties, although their structures are very similar. Surprisingly, doping of the three host structures with Eu3+ and Tb3+ ions was only successful for one of the polymorphs.
Co-reporter:Norbert Stock and Shyam Biswas
Chemical Reviews 2012 Volume 112(Issue 2) pp:933-969
Publication Date(Web):November 18, 2011
DOI:10.1021/cr200304e
Co-reporter:Shyam Biswas, Michael Maes, Amarajothi Dhakshinamoorthy, Mark Feyand, Dirk E. De Vos, Hermenegildo Garcia and Norbert Stock
Journal of Materials Chemistry A 2012 vol. 22(Issue 20) pp:10200-10209
Publication Date(Web):03 Feb 2012
DOI:10.1039/C2JM15592C
Two isostructural microporous metal–organic frameworks [Co(DMA)6]3[(Co4Cl)3(BTT)8(H2O)12]2·12H2O (BTT3− = 1,3,5-benzenetristetrazolate; DMA = N,N′-dimethylacetamide) (1) and [Cd(DMF)6]3[(Cd4Cl)3(BTT)8(H2O)12]2·14H2O·4DMF (DMF = N,N′-dimethylformamide) (2) were synthesized under solvothermal conditions. The structures of both compounds were determined by single-crystal X-ray diffraction data. Each compound adopts a porous three-dimensional framework consisting of square-planar [M4Cl]7+ (M2+ = Co, 1; Cd, 2) units interconnected by triangular tritopic BTT3− bridging ligands to give an anionic (3,8)-connected “Moravia” net. Phase purity of the compounds was confirmed by X-ray powder diffraction (XRPD), IR spectroscopy, thermogravimetric (TG) and elemental analysis. TGA and temperature-dependent XRPD (TDXRPD) experiments indicate a moderate thermal stability up to 350 and 300 °C, respectively. Guest exchange followed by heating led to microporous solids with coordinatively unsaturated metal sites. These unsaturated metal sites create opportunities in adsorptive and catalytic applications. These have been probed by the selective removal of sulfur compounds from fuel feeds as well as the catalytic ring opening of styrene oxide and the oxidation of several cycloalkanes and benzyl compounds.
Co-reporter:Helge Reinsch, Bartosz Marszałek, Julia Wack, Jürgen Senker, Barbara Gil and Norbert Stock
Chemical Communications 2012 vol. 48(Issue 76) pp:9486-9488
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2CC34909D
The new Al-based metal–organic framework [Al13(OH)27(H2O)6(BDC-NH2)3Cl6(C3H7OH)6] denoted CAU-6 (CAU = Christian-Albrechts-Universität) was solvothermally synthesized in 2-propanol and was thoroughly characterized. The framework structure exhibits a unique column-shaped inorganic building unit, which is based on stacked, corner-sharing Al13-clusters. The compound exhibits unprecedented hydrophilicity for metal–organic frameworks.
Co-reporter:Corinna Schmidt
Inorganic Chemistry 2012 Volume 51(Issue 5) pp:3108-3118
Publication Date(Web):February 10, 2012
DOI:10.1021/ic202589s
With the high-throughput (HT) methodology, the bifunctional aminoalkylphosphonic acids (AAPA) linker molecules 2-aminoethyl- (AEPA), 3-aminopropyl- (APPA), and 4-aminobutylphosphonic acid (ABPA) [HO3P–CnH2n–NH2 (n = 2–4)] and zinc nitrate were used to synthesize new metal phosphonates in order to investigate the influence of the alkyl chain length on the structure formation. The systematic investigations led to one known (ZnO3PC2H4NH2) and six new compounds: one using AEPA, three using APPA, and two using ABPA. The crystal structures of five compounds were determined by single crystal X-ray diffraction, using X-ray powder diffraction (XRPD) data as well as structure modeling employing force field methods. For compound 1, Zn(O3P–C2H4–NH3)(NO3)(H2O) (monoclinic, Cc, a = 4.799(1) Å, b = 29.342(6) Å, c = 5.631(1) Å, β = 91.59(3)°, V = 792.7(3) Å3, Z = 4), and compound 2, Zn2(OH)(O3P–C3H6–NH3)(NO3) (monoclinic, P2/c, a = 12.158(2) Å, b = 5.0315(10) Å, c = 13.952(3) Å, β = 113.23(3)°, V = 784.3(3) Å3, Z = 2), the structures were determined using single crystal X-ray diffraction data. The crystal structures of [Zn(O3P–C3H6–NH2)]·H2O (3) (monoclinic, P21/c, a = 9.094(2) Å, b = 5.0118(7) Å, c = 16.067(4) Å, β = 90.38(2)°, V = 732.3(2) Å3, Z = 4) and Zn(O3P–C4H8–NH2) (5) (monoclinic, P21/c, a = 8.570(7) Å, b = 8.378(4) Å, c = 9.902(6) Å, β = 90.94(5)°, V = 710.9(8) Å3, Z = 4) were determined using XRPD data. The structural model for compound 6, Zn(O3P–C4H8–NH3)(NO3)(H2O), was established using lattice parameters from XRPD data and following crystal structure modeling employing force field methods. The structures depend strongly on the alkyl chain length n. For n = 2 and 4 isoreticular compounds are observed, while n = 3 leads to new structures. Larger amounts of all compounds were obtained employing scale-up syntheses in a conventional oven as well as in a microwave reactor system. In addition, in situ energy dispersive X-ray diffraction (EDXRD) experiments at 130 °C were performed at beamline F3 at HASYLAB, DESY, Hamburg, to investigate the formation of compounds 2 and 3 as well as the phase transformation of 2 into 3 upon addition of NaOH. All compounds were characterized in detail using X-ray powder diffraction, IR/Raman spectroscopy, and thermogravimetric and elemental analysis.
Co-reporter:Mark Feyand, Annika Hübner, André Rothkirch, David S. Wragg, and Norbert Stock
Inorganic Chemistry 2012 Volume 51(Issue 22) pp:12540-12547
Publication Date(Web):November 9, 2012
DOI:10.1021/ic301976s
The system Cu2+/H2O3P–C2H4–SO3H/NaOH was investigated using in situ energy dispersive X-ray diffraction (EDXRD) to study the formation and temperature induced phase transformation of previously described copper phosphonosulfonates. Thus, the formation of [Cu2(O3P–C2H4–SO3)(OH)(H2O)]·3H2O (4) at 90 °C is shown to proceed via a previously unknown intermediate [Cu2(O3P–C2H4–SO3)(OH)(H2O)]·4H2O (6), which could be structurally characterized from high resolution powder diffraction data. Increase of the reaction temperature to 150 °C led to a rapid phase transformation to [Cu2(O3P–C2H4–SO3)(OH)(H2O)]·H2O (1), which was also studied by in situ EDXRD. The comparison of the structures of 1, 4, and 6 allowed us to establish a possible reaction mechanism. In addition to the in situ crystallization studies, microwave assisted heating for the synthesis of the copper phosphonosulfonates was employed, which allowed the growth of larger crystals of [NaCu(O3P–C2H4–SO3)(H2O)2] (5) suitable for single crystal X-ray diffraction. Through the combination of force field calculations and Rietveld refinement we were able to determine the crystal structure of [Cu1.5(O3P–C2H4–SO3)] 2H2O (3) and thus structurally characterize all compounds known up to now in this well investigated system. With the additional structural data we are now able to describe the influence of the pH on the structure formation.
Co-reporter:Antje Modrow, Dordaneh Zargarani, Rainer Herges and Norbert Stock
Dalton Transactions 2012 vol. 41(Issue 28) pp:8690-8696
Publication Date(Web):21 May 2012
DOI:10.1039/C2DT30672G
For the first time an azo functionality was covalently introduced into a MOF by post-synthetic modification. The reaction of Cr-MIL-101-NH2 with p-phenylazobenzoylchloride (1) and 4-(phenylazo)phenylisocyanate (2) as the reactants led to the compounds Cr-MIL-101_amide and Cr-MIL-101_urea, with the azo groups protruding into the mesoporous cages. XRPD and N2 sorption measurements confirm the intactness of the framework and the successful covalent modification was proven by IR- and NMR-spectroscopy. Furthermore, cis/trans isomerisation upon irradiation with light was demonstrated by UV/Vis spectroscopy. More distinct changes in the UV/Vis spectra were observed for Cr-MIL-101_amide compared to Cr-MIL-101_urea, while the degree of functionalization, i.e. the number of reacted NH2-groups, seems to have a less pronounced effect. The variation of the sorption properties due to the cis/trans isomerisation was proven by methane adsorption measurements.
Co-reporter:Nele Reimer, Barbara Gil, Bartosz Marszalek and Norbert Stock
CrystEngComm 2012 vol. 14(Issue 12) pp:4119-4125
Publication Date(Web):30 Jan 2012
DOI:10.1039/C2CE06649A
Aluminium trimellitate [Al(OH)(BDC–COOH)]·0.9H2O (1), the Al-MIL-53–COOH derivative, was discovered under solvothermal conditions using a high-throughput set-up suitable for microwave (MW)-assisted heating. The compound shows high structural flexibility. The large-pore (lp) form of the framework is obtained under large excess of H2O or after solvothermal treatment with N,N-dimethylformamide upon which [Al(OH)(BDC–COOH)]·0.7DMF (2) is obtained. Exposure of the water rich lp form of 1 to ambient conditions leads to the transformation to the narrow-pore (np) form. Thermal activation of both compounds results in the formation of the empty lp form and the activation of 1 was studied in detail by in situ IR-spectroscopy. Depending on the activation temperature and time two post-synthetic modification (PSM) processes are observed: the partial decarboxylation and the formation of acid anhydride groups. Thus at high temperatures and long activation times [Al(OH)(BDC–OCOCO–BDC)x/2(BDC)y] (x + y = 1) is formed. Upon cooling in air the anhydride functionality still remains intact, but the np form is obtained in air due to the adsorption of H2O molecules. Sorption measurements of 1 confirm a preference for polar gases like H2O and CO2 in comparison to N2, H2, and CH4. The N2 capacity depends strongly on the degree of decarboxylation.
Co-reporter:Tim Ahnfeldt, Daniel Gunzelmann, Julia Wack, Jürgen Senker and Norbert Stock
CrystEngComm 2012 vol. 14(Issue 12) pp:4126-4136
Publication Date(Web):16 Feb 2012
DOI:10.1039/C2CE06620C
Four new porous CAU-1 derivatives CAU-1–NH2 ([Al4(OH)2(OCH3)4(BDC–NH2)3]·xH2O, BDC–NH22− = aminoterephthalate), CAU-1–NH2(OH) ([Al4(OH)6(BDC–NH2)3]·xH2O), CAU-1–NHCH3 ([Al4(OH)2(OCH3)4(BDC–NHCH3)3]·xH2O) and CAU-1–NHCOCH3 ([Al4(OH)2(OCH3)4(BDC–NHCOCH3)3]·xH2O) all containing an octameric [Al8(OH)4+y(OCH3)8−y]12+ cluster, with y = 0–8, have been obtained by MW-assisted synthesis and post-synthetic modification. The inorganic as well as the organic unit can be modified. Heteronuclear 1H–15N, 1H–13C and homonuclear 1H–1H connectivities determined by solid-state NMR spectroscopy prove the methylation of the NH2 groups when conventional heating is used. Varying reaction times and temperatures allow controlling the degree of methylation of the amino groups. Short reaction times lead to non-methylated CAU-1 (CAU-1–NH2), while longer reaction times result in CAU-1–NHCH3. CAU-1–NH2 can be modified chemically by using acetic anhydride, and the acetamide derivative CAU-1–NHCOCH3 is obtained. Thermal treatment permits us to change the composition of the Al-containing unit. Methoxy groups are gradually exchanged by hydroxy groups at 190 °C in air. Solid-state NMR spectra unequivocally demonstrate the presence of the amino groups, as well as the successful post-synthetic modification. Furthermore 1H–1H correlation spectra using homonuclear decoupling allow the orientation of the NHCOCH3 groups within the pores to be unravelled. The influence of time and temperature on the synthesis of CAU-1 was studied by X-ray powder diffraction, elemental analyses, and 1H liquid-state NMR and IR spectroscopy.
Co-reporter:Tim Ahnfeldt and Norbert Stock
CrystEngComm 2012 vol. 14(Issue 2) pp:505-511
Publication Date(Web):27 Oct 2011
DOI:10.1039/C1CE05956D
Two isoreticular aluminium containing metal–organic frameworks, CAU-1-NH2 and CAU-1-(OH)2, have been synthesized solvothermally using 2-aminoterephthalic and 2,5-dihydroxyterpththalic acid to elucidate the product formation depending on the functionalized carboxylic acids. Here, we focus on the product formation kinetics of the amino-functionalized CAU-1, i.e.CAU-1-NH2. The reactions were studied by in situ energy dispersive X-ray diffraction (EDXRD) experiments in the temperature range of 115–145 °C. Both conventional electric (CE) and microwave (MW) -assisted heating were employed. The latter led to shorter induction periods as well as shorter crystallisation times compared to the conventional synthesis. In analogy with the previously reported results of the EDXRD studies of the formation of CAU-1-(OH)2, similar crystal growth rates were observed for both CAU-1-NH2 and CAU-1-(OH)2 using CE heating. In contrast, MW-assisted synthesis of CAU-1-NH2 led to a shorter induction period as well as an acceleration of the crystal growth compared to CAU-1-(OH)2. The acceleration in the crystal growth stage of CAU-1-NH2 can be attributed to a larger pre-exponential factor (about three times that of CAU-1-(OH)2) derived from the Arrhenius plot. However, the activation energy of the crystal growth exhibits similar values for both MW-assisted and CE synthesis of CAU-1-NH2 and CAU-1-(OH)2.
Co-reporter:Helge Reinsch, Mark Feyand, Tim Ahnfeldt and Norbert Stock
Dalton Transactions 2012 vol. 41(Issue 14) pp:4164-4171
Publication Date(Web):30 Jan 2012
DOI:10.1039/C2DT12005D
A new family of Al-based MOFs denoted as CAU-3 (CAU = Christian-Albrechts-Universität) was discovered in the solvothermal system Al3+/aryldicarboxylic acid/NaOH/methanol by applying high-throughput-methods. The three compounds reported in this article [Al2(OCH3)4BDC], [Al2(OCH3)4BDC-NH2] and[Al2(OCH3)4NDC] (BDC = 1,4-benzenedicarboxylate; NDC = 2,6-naphtalenedicarboxylate) are all based on the same unprecedented inorganic building unit [Al12(OCH3)24]12+, which is a dodecameric cyclic aluminium-methanolate-cluster. The material CAU-3-NDC was found to exhibit the highest surface area as well as the highest micropore volume of all Al-based MOFs reported until now.
Co-reporter:Helge Reinsch, Martin Krüger, Julia Wack, Jürgen Senker, Fabrice Salles, Guillaume Maurin, Norbert Stock
Microporous and Mesoporous Materials 2012 Volume 157() pp:50-55
Publication Date(Web):15 July 2012
DOI:10.1016/j.micromeso.2011.05.029
The system Al3+/H3BTB/DMF/additive was systematically investigated using high-throughput methods and the new, microporous MOF [Al(BTB)] (BTB = 1,3,5-benzenetrisbenzoate), named CAU-4 (CAU = Christian-Albrechts-University), was discovered. The synthesis was optimized changing chemical and process parameters and the final synthesis procedure was scaled up to the gram scale. CAU-4 is thermally stable up to 400 °C in air and exhibits a BET-surface area of 1520 m2/g and a micropore volume of 0.61 cm3/g. A structure model was developed using a computationally assisted structure determination that was further validated by a good agreement with the experimental X-ray diffraction patterns and the geometrical features. The framework structure consists of isolated [AlO6]-octahedra which are bridged by carboxylate groups of the BTB-linker to form chains. These chains are connected by the tritopic aromatic building blocks, to form one-dimensional hexagonal channels with a diameter of ca. 9.6 Å.Graphical abstractHighlights► CAU4 is a new, highly porous and thermally stable Al-containing MOF. ► CAU-4 contains one-dimensional pores with a diameter of ∼1 nm. ► Structure simulation and spectroscopic investigations led to a structural model.
Co-reporter:Corinna Schmidt, Mark Feyand, André Rothkirch, Norbert Stock
Journal of Solid State Chemistry 2012 Volume 188() pp:44-49
Publication Date(Web):April 2012
DOI:10.1016/j.jssc.2012.01.044
The system Ca2+/2-aminoethylphosphonic acid/H2O/NaOH was systematically investigated using high-throughput methods. The experiments led to one new compound Ca(O3PC2 H4NH2) (1) and the crystal structure was determined using in house X-ray powder diffraction data (monoclinic, P21/c, a=9.7753(3), b=6.4931(2), c=8.4473(2) Å, β=106.46(2)°, V=514.20(2) Å3, Z=4). The formation of 1 was investigated by in situ energy dispersive X-ray diffraction measurements (EDXRD) at beamline F3 at HASYLAB (light source DORIS III), DESY, Hamburg. An intermediate, Ca(OH)(O3PC2H4NH3)·2H2O (2), was observed and could be isolated from the reaction mixture at ambient temperatures by quenching the reaction. The crystal structure of 2 was determined from XRPD data using synchrotron radiation (monoclinic, P21/m, a=11.2193(7), b=7.1488(3), c=5.0635(2) Å, β=100.13(4)°, V=399.78(3) Å3, Z=2).Graphical abstarctThe detailed in situ energy dispersive X-ray diffraction (EDXRD) investigation on the formation of the new inorganic–organic hybrid compound Ca(O3PC2H4NH2) leads to the discovery of a new crystalline intermediate phase. Both crystal structures were elucidated using X-ray powder diffraction data.Highlights► High-throughput investigation led to new metal aminoethylphosphonate Ca(O3PC2H4NH2). ► The formation of Ca(O3PC2H4NH2) was followed by in situ EDXRD measurements. ► The crystalline intermediate Ca(O3PC2H4NH3)(OH)·2H2O was discovered. ► Isolation of Ca(O3PC2H4NH3)(OH)·2H2O was accomplished by quenching experiments. ► The structures were determined using X-ray powder diffraction data.
Co-reporter:Mark Fey;Dr. Enrico Mugnaioli;Frederik Vermoortele;Bart Bueken;Dr. Johannes M. Dieterich;Tim Reimer;Dr. Ute Kolb;Dr. Dirk deVos;Dr. Norbert Stock
Angewandte Chemie 2012 Volume 124( Issue 41) pp:10519-10522
Publication Date(Web):
DOI:10.1002/ange.201204963
Co-reporter:Mark Fey;Dr. Enrico Mugnaioli;Frederik Vermoortele;Bart Bueken;Dr. Johannes M. Dieterich;Tim Reimer;Dr. Ute Kolb;Dr. Dirk deVos;Dr. Norbert Stock
Angewandte Chemie International Edition 2012 Volume 51( Issue 41) pp:10373-10376
Publication Date(Web):
DOI:10.1002/anie.201204963
Co-reporter:Yan Meng, Guang-Hui Wang, Stephan Bernt, Norbert Stock and An-Hui Lu
Chemical Communications 2011 vol. 47(Issue 37) pp:10479-10481
Publication Date(Web):19 Aug 2011
DOI:10.1039/C1CC13699B
A crystal-like ordered microporous inorganic hybrid solid was prepared using silane functionalized Cr-MIL-101 (Si-MIL-101) as the precursor, via a surface coating reinforced framework strategy.
Co-reporter:Stephan Bernt, Vincent Guillerm, Christian Serre and Norbert Stock
Chemical Communications 2011 vol. 47(Issue 10) pp:2838-2840
Publication Date(Web):21 Jan 2011
DOI:10.1039/C0CC04526H
For the first time, functionality has been covalently introduced into the Cr-MIL-101 network by post-synthetic modification of the terephthalate linker molecule through nitration. The nitro group was reduced and the amino group was reacted with ethyl isocyanate to yield the corresponding urea derivative.
Co-reporter:Palanikumar Maniam
Inorganic Chemistry 2011 Volume 50(Issue 11) pp:5085-5097
Publication Date(Web):May 3, 2011
DOI:10.1021/ic200381f
In the search of Ni based metal–organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni2+/HnL/base/solvent with HnL = H3BTC (1,3,5-benzenetricarboxylic acid), H3BTB (4,4′,4′′,-benzene-1,3,5-triyl-tris(benzoic acid)), and H2BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H3BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni3(BTC)2(Me2NH)3]·(DMF)4(H2O)4 (1a) and [Ni6(BTC)2(DMF)6(HCOO)6] (1b) were discovered (Me2NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H3BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni3(BTB)2(2-MeIm)1.5(H2O)1.5]·(DMF)9(H2O)6.5 (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H2O and H2 with a strong hysteresis. In the third system, H2BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni2(BDC)2(DABCO)]·(DMF)4(H2O)1.5 (3a) and [Ni2(BDC)2(DABCO)]·(DMF)4(H2O)4 (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)1.5(H2O)2 (3c) were isolated. The 3a and 3b polymorphs of the [Ni2(BDC)2(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2, 3a, 3b, and 3c. All compounds were structurally characterized. In addition to IR, elemental and TG analyses, gas and vapor sorption experiments were carried out.
Co-reporter:Shyam Biswas, Tim Ahnfeldt, and Norbert Stock
Inorganic Chemistry 2011 Volume 50(Issue 19) pp:9518-9526
Publication Date(Web):September 7, 2011
DOI:10.1021/ic201219g
Five new flexible functionalized aluminum hydroxo terephthalates [Al(OH)(BDC-X)]·n(guests) (BDC = 1,4-benzene-dicarboxylate; X = -Cl, 1-Cl; -Br, 2-Br; -CH3, 3-CH3; -NO2, 4-NO2; -(OH)2, 5-OH2) were synthesized under solvothermal conditions. The as synthesized (Al-MIL-53-X-AS) as well as the activated compounds were characterized by X-ray powder diffraction (XRPD), IR spectroscopy, thermogravimetric (TG), and elemental analysis. Activation, that is, removal of unreacted H2BDC-X molecules and/or occluded solvent molecules, followed by hydration in air at room temperature, led to the narrow pore (NP) form of the title compounds [Al(OH)(BDC-X)]·n(H2O) (Al-MIL-53-X). Thermogravimetric analysis (TGA) and temperature-dependent XRPD (TDXRPD) experiments performed on the NP-form of the compounds indicate high thermal stability in the range 325–500 °C. As verified by N2, CO2, or H2O sorption measurements, most of the thermally activated compounds exhibit significant microporosity. Similar to pristine Al-MIL-53, the present compounds retain their structural flexibility depending on the nature of guest molecules and temperature, as verified by cell parameter determination from XRPD data. The breathing behavior of the functionalized frameworks upon dehydration–rehydration, investigated by temperature and time-dependent XRPD measurements, differs significantly compared to parent Al-MIL-53.
Co-reporter:Corinna Schmidt and Norbert Stock
Crystal Growth & Design 2011 Volume 11(Issue 12) pp:5682-5687
Publication Date(Web):October 25, 2011
DOI:10.1021/cg2012205
Using the bifunctional metalloligand bis(2-carboxyethylgermanium sesquioxide) (HOOCCH2CH2Ge)2O3, we carried out a high-throughput (HT) study in the system Cu2+/(HOOCCH2CH2Ge)2O3/H2O/2-propanol. The HT experiment included 72 individual reactions, which were employed to study the influence of the molar ratio of the starting materials and the volume fraction of the solvents on the product formation. One new compound Cu(OOCC2H4Ge)2O3 (1) (monoclinic, P21/n, a = 1348.36(4), b = 509.64(1), c = 1599.21(5) pm, β = 114.44(1)°, V = 1000.45(5) × 106 pm3, Z = 4) was obtained and characterized in detail using single crystal X-ray diffraction, scanning electron microscopy (SEM), thermogravimetric (TG) measurements, and IR spectroscopy. The title compound crystallizes in thin blue-colored needles. The crystal structure contains alternating chains of 4-rings of corner-sharing GeO3C-polyhedra and chains of Cu2O8 paddle-wheel units. Their interconnection leads to the formation of layers that are held together by van der Waals interactions. The formation of the title compound was also explored by in situ energy dispersive X-ray diffraction (EDXRD) measurements using conventional heating in the temperature range 120–140 °C. Using the Avrami-Eroféev equation and the Sharp–Hancock method, Avrami exponents in a range of 1.65–1.87 are obtained, which suggests a nucleation controlled reaction mechanism for the crystallization process. All rate constants are in the 0.029(3)–0.242(3) s–1 range, and the Arrhenius activation energy was determined to be 113(7) kJ/mol.
Co-reporter:Antje Modrow, Dordaneh Zargarani, Rainer Herges and Norbert Stock
Dalton Transactions 2011 vol. 40(Issue 16) pp:4217-4222
Publication Date(Web):10 Mar 2011
DOI:10.1039/C0DT01629B
We synthesized a porous twofold interpenetrated MOF [Zn2(NDC)2(1)] (coined CAU-5) using 3-azo-phenyl-4,4′-bipyridine (1), 2,6-naphthalenedicarboxylic acid, and Zn(NO3)2·6H2O. The azo-functionality protrudes into the pores, and can be switched, by irradiation with UV light (365 nm), from the thermodynamically stable trans-isomer to the cis-isomer. Back-switching was achieved thermally and with an irradiation wavelength of λmax = 440 nm.
Co-reporter:Stephan Bernt;Mark Fey;Antje Modrow;Julia Wack;Jürgen Senker
European Journal of Inorganic Chemistry 2011 Volume 2011( Issue 35) pp:5378-5383
Publication Date(Web):
DOI:10.1002/ejic.201100789
Abstract
We report the synthesis and characterization of the new switchable Zn-based zeolitic imidazolate framework (ZIF) [Zn(Im)(aIm)] (1). The high-throughput investigation of the mixed linker system Zn2+/imidazole (HIm)/2-phenylazoimidazole (HaIm)/DMF at 85 °C led to 1, which is isostructural to ZIF-8 and crystallizes in a sodalite (SOD)-type structure. The preparation was also studied with microwave-assisted heating and ultrasound-assisted synthesis. The crystal structure was determined from single-crystal X-ray diffraction data. Although Im– and aIm– ions are present in a 1:1 molar ratio, no ordering of the 2-phenylazo group was observed. Incorporation of the Im– and aIm– linkers as an integral part of the framework structure was confirmed by elemental analysis, 13C and 15N MAS NMR, IR and Raman spectroscopy. In addition, the permanent porosity of 1 was demonstrated by N2 sorption experiments and a specific surface area of SBET = 580 m2 g–1 is observed. The photoswitching properties were investigated by UV/Vis spectroscopy as the cis and trans isomers exhibit different UV absorption spectra. Switching can be achieved by irradiation with UV light (λ = 355 nm), and back-switching using visible light (λ = 525 nm). Although changes in the UV/Vis spectra are detected, the switching process is only partially reversible.
Co-reporter:Tim Ahnfeldt;Jens Moellmer;Vincent Guillerm; Reiner Staudt;Dr. Christian Serre; Norbert Stock
Chemistry - A European Journal 2011 Volume 17( Issue 23) pp:6462-6468
Publication Date(Web):
DOI:10.1002/chem.201003708
Abstract
Aluminium dihydroxyterephthalate [Al8(OH)4(OCH3)8(BDC(OH)2)6]⋅x H2O (denoted CAU-1-(OH)2) was synthesized under solvothermal conditions and characterized by X-ray powder diffraction, IR spectroscopy, sorption measurements, as well as thermogravimetric and elemental analysis. CAU-1-(OH)2 is isoreticular to CAU-1 and its pores are lined with OH groups. It is stable under ambient conditions and in water, and it exhibits permanent porosity and two types of cavities with effective diameters of approximately 1 and 0.45 nm. The crystallization of CAU-1-(OH)2 was studied by in situ energy-dispersive X-ray diffraction (EDXRD) experiments in the 120–145 °C temperature range. Two heating methods—conventional and microwave—were investigated. The latter leads to shorter induction periods as well as shorter reaction times. Whereas CAU-1-(OH)2 is formed at all investigated temperatures using conventional heating, it is only observed below 130 °C using microwave heating. The calculation of the activation energy of the crystallization of CAU-1-(OH)2 exhibits similar values for microwave and conventional synthesis.
Co-reporter:Mark Feyand, Christian Näther, André Rothkirch, and Norbert Stock
Inorganic Chemistry 2010 Volume 49(Issue 23) pp:11158-11163
Publication Date(Web):November 8, 2010
DOI:10.1021/ic101786r
Using the flexible linker H2O3P-C4H8-SO3H (H3L) and rare earth ions Ln3+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) we were able to synthesize the new isostructural inorganic organic hybrid compounds Ln(O3P-C4H8-SO3)(H2O). High-throughput experiments were employed to study the influence of the molar ratios Ln:H3L and pH on the product formation. The crystal structure of the compounds Sm(O3P-C4H8-SO3)(H2O) (1) and Pr(O3P-C4H8-SO3)(H2O) (2) were determined by single crystal diffraction. The structures are built up from chains of edge-sharing LnO8-polyhedra that are connected by the phosphonate and sulfonate groups into layers. These layers are linked by the −(CH2)4− group to form a three-dimensional framework. The synthesis of compound 1 was scaled up in a conventional oven as well as in a microwave reactor system. A modification of a microwave reactor system allowed its integration into the beamline F3 at HASYLAB, DESY, Hamburg. The crystallization was investigated in situ by means of energy dispersive X-ray diffraction using conventional as well as microwave heating methods applying temperatures varying from 110 to 150 °C. The formation of Sm(O3P-C4H8-SO3)(H2O) takes place in two steps. In the first step a crystalline intermediate was observed, which transforms completely into compound 1. The method by Sharp and Hancock was used to determine the rate constants, reaction exponents, and the Arrhenius activation energy for both reaction steps. Comparing both heating methods, microwave heating leads to fully crystallized reaction product after shorter reaction times, but neither the temperature nor the heating method has significant influence on the induction time.
Co-reporter:Norbert Stock
Microporous and Mesoporous Materials 2010 Volume 129(Issue 3) pp:287-295
Publication Date(Web):15 April 2010
DOI:10.1016/j.micromeso.2009.06.007
High-throughput (HT) methods applied to solvothermal reaction systems are a powerful technique for the rapid systematic investigation of large parameter spaces in a short time, giving rise to the accelerated discovery of new compounds and optimization of synthesis parameters. Large amounts of data can be generated in a short period of time, which provides the opportunity to extract relevant reaction trends and contribute to a better understanding of the role of reaction parameters. While the primary driving forces in the development of high-throughput methods have been commercial considerations to cut down the time to market for new or improved products, the methodology is also well suited for investigations in academia. The fields of application range from the discovery of new compounds, the optimization of syntheses conditions to the extraction of synthesis trends. Examples demonstrating the power of HT methods will be based on different classes of compounds such as zeolites, inorganic–organic hybrid compounds such as ZIFs, MOFs and MILs and will range from the investigation of two-dimensional to multi-dimensional parameter spaces.
Co-reporter:Palanikumar Maniam;Christian Näther
European Journal of Inorganic Chemistry 2010 Volume 2010( Issue 24) pp:3866-3874
Publication Date(Web):
DOI:10.1002/ejic.201000393
Abstract
A high-throughput (HT) investigation using the rigid bifunctional ligand 4-phosphonobenzenesulfonic acid, H2O3P-C6H4-SO3H (H3L), generated five new phosphonatobenzenesulfonates with copper(II) or lead(II) ions. A comprehensive HT study comprising the screenings of different metal ions, metal salt types and the synthesis optimization were conducted whereby the influence of pH and molar ratios M2+/H3L were investigated. The HT-study led to five new compounds Pb2[(O3P-C6H4-SO3)(OH)] (1), Cu1.5[(O3P-C6H4-SO3)(H2O)] (2), NaCu(O3P-C6H4-SO3)(H2O)3 (3), Cu2[(O3P-C6H4-SO3)(OH)(H2O)] (4) and Cu3[(O3P-C6H4-SO3)2(H2O)2] (5). Metal ion screening showed lead(II) and copper(II) to be suitable metal ions. The utilization of discovery and focused arrays allowed to determine the optimal formation fields of the respective compounds. The crystal structures were determined from single-crystal X-ray diffraction and revealed the presence of various MOx polyhedra that form clusters, chains or layers which are connected through the organic linker. IR spectra, thermogravimetric studies, magnetic susceptibility measurements and elemental analyses were conducted to further characterize the compounds 1, 3, 4 and 5.
Co-reporter:N. Stock
Chemie Ingenieur Technik 2010 Volume 82( Issue 7) pp:1039-1047
Publication Date(Web):
DOI:10.1002/cite.201000029
Abstract
Hochdurchsatz (HD)-Methoden erlauben eine systematische und effiziente Untersuchung komplexer Parameterräume, wie sie oft bei Solvothermalsynthesen beobachtet werden. Ihr Einsatz ermöglicht es, schneller neue Verbindungen zu entdecken, Synthesebedingungen zu optimieren bzw. Reaktionstrends ausfindig zu machen. Mit einem unterschiedlichen Ausmaß an Parallelisierung, Miniaturisierung und Automatisierung der einzelnen Arbeitsschritte wurden innerhalb des letzten Jahrzehnts einige HD-Methodiken entwickelt, deren Einsatz zu neuen herausragenden mikroporösen Verbindungen im Bereich der Zeolithe, ZIFs (zeolithic imidazolate frameworks) und MOFs (metal-organic frameworks) geführt haben.
Co-reporter:Tim Ahnfeldt ; Daniel Gunzelmann ; Thierry Loiseau ; Dunja Hirsemann ; Jürgen Senker ; Gerard Férey
Inorganic Chemistry 2009 Volume 48(Issue 7) pp:3057-3064
Publication Date(Web):February 26, 2009
DOI:10.1021/ic8023265
Aluminum aminoterephthalate Al(OH)[H2N−BDC]·0.3(H2N−H2BDC (denoted MIL-53−NH2(as)) was synthesized under hydrothermal conditions. The activation of the compound can be achieved in two steps. The treatment with DMF at 150 °C leads to Al(OH)[H2N−BDC]·0.95DMF (MIL-53−NH2(DMF)). In the second step, DMF is thermally removed at 130 °C. Upon cooling in air, the hydrated form Al(OH)[H2N−BDC]·0.9H2O (MIL-53−NH2(lt)) is obtained. The dehydration leads to a porous compound that exhibits hysteresis behavior in the N2 sorption experiments. The MIL-53−NH2(lt) can be modified by postsynthetic functionalization using formic acid, and the corresponding amide Al(OH)[HC(O)N(H)−BDC]·H2O (MIL-53−NHCHO) is formed. All four phases were thoroughly characterized by X-ray powder diffraction, solid-state NMR and IR spectroscopy, and sorption measurements, as well as thermogravimetric and elemental analysis. Based on the refined lattice parameter similar breathing behavior of the framework as found in the unfunctionalized MIL-53 can be deduced. Solid-state NMR spectra unequivocally demonstrate the presence of the guest species, as well as the successful postsynthetic functionalization.
Co-reporter:Andreas Sonnauer, Mark Feyand and Norbert Stock
Crystal Growth & Design 2009 Volume 9(Issue 1) pp:586-592
Publication Date(Web):November 24, 2008
DOI:10.1021/cg8008865
The bifunctional linker 4-phosphonobutanesulfonic acid, H2O3P−C4H8−SO3H (H3L), was synthesized and characterized in detail and its use in the synthesis of new copper phosphonates was investigated. Thus, a high-throughput (HT) study was started for the systematic investigation of the system Cu(NO3)2/H3L/NaOH/H2O. An HT experiment comprising 48 individual hydrothermal reactions was performed to systematically investigate the influence of pH of the starting mixture as well as the molar ratio Cu2+:H3L. Two new compounds [Cu1.5(O3P−C4H8−SO3)(H2O)]·1.15H2O (1) and Cu2.5(O3P−C4H8−SO3)(OH)2 (2) were obtained. On the basis of scanning electron microscope images, the crystal sizes of both compounds were determined and a trend of the crystal size was established. The synthesis of both compounds was up-scaled in glass reactors by a factor of 10. While for 1 suitable single crystals for single-crystal diffraction measurement could be obtained, for 2 only multiple twinned crystals could be found. A structural model could be extracted, which was refined using Rietveld methods. Compound 1 contains a trimeric Cu3O12 cluster composed of two CuO5 and one CuO6 polyhedra. These trimers are connected by the -C4H8- group of the ligand to double layers, which are interconnected via hydrogen bonds to a three-dimensional framework. Compound 2 is built up from CuO6 polyhedra forming M-O-M layers. These layers are connected by the -C4H8- groups to a three-dimensional pillared framework. This leads to antiferromagnetic and ferromagnetic interactions at low temperatures for 1 and 2, respectively. In addition, the results of thermogravimetric investigations and IR spectra are also presented.
Co-reporter:Monika Plabst, Norbert Stock and Thomas Bein
Crystal Growth & Design 2009 Volume 9(Issue 12) pp:5049-5060
Publication Date(Web):November 10, 2009
DOI:10.1021/cg8014173
Benzylbisphosphonic acid C6H5-CH(PO3H2)2, H4L, and 1,4-phenylenebis(methylidyne)tetrakis(phosphonic acid), H8L, were synthesized and characterized. In a combinatorial approach, their reactions with a library of amines were investigated. The crystal structures of (NH3CH2-C6H4-CH2NH3)1.5 [C6H5-CH(PO3)2H]·4H2O, 2(H4L)·3b, (C6H5-NH3)2[C6H5-CH(PO3)2H2], H4L·2c, (C5H10NH2)[C6H5-CH(PO3)2H3], H4L·i, (C5H5NH)[C6H5-CH(PO3)2H3], H4L·m, (NH3-C2H4-NH3)0.5[C6H5-CH(PO3)2H3)]·CH3OH, 2(H4L)·n, (C3N6H7)2[C6H5-CH(PO3)2H2]·4H2O, H4L·2s, and (NH3CH2-C6H4-CH2NH3)[H3(PO3)2CH-C6H4-CH(PO3)2H3]·1.5H2O, H8L·b, could be resolved and studied with special regard to the hydrogen-bonding of the molecular building blocks. Four different motifs of hydrogen bonding between the phosphonate groups could be observed: a single hydrogen bond, a dimeric R22(8) ring motif, the association of two bisphosphonate units into a dimer by two 2-fold hydrogen bonds, and an intramolecular hydrogen bond forming a six-membered ring. Cross-linking of the bisphosphonate groups via [O−H···O] bridges between phosphonates and in some cases solvent molecules generates two-dimensional networks. In the presence of a bifunctional organoammonium ion with a size-suitable rigid spacer unit, [N−H···O] bridges extend the network to the third dimension. All compounds provide structures with hydrophobic and hydrophilic regions.
Co-reporter:Enrica Biemmi, Sandra Christian, Norbert Stock, Thomas Bein
Microporous and Mesoporous Materials 2009 Volume 117(1–2) pp:111-117
Publication Date(Web):1 January 2009
DOI:10.1016/j.micromeso.2008.06.040
High-throughput methods were employed to study the influence of reaction parameters on the synthesis of the metal-organic frameworks MOF-5 (Zn4O[(OOC)2 · C6H4]3) and HKUST-1 (Cu3[(OOC)3C6H3]2(H2O)3 · xH2O). Thus, compositional parameters (metal salt, reagent concentrations, and pH) as well as process parameters (temperature, time) were investigated in order to establish reaction trends and fields of formation. A multiclave reaction block was used to perform the investigation of 24 different solvothermal reactions at a time. Attention was focused on the phase purity and the crystal morphology of the resulting compounds. The characterization of the samples was performed by X-ray powder diffraction and high resolution scanning electron microscopy. The experimental results show that the formation, phase purity, and morphology of MOF-5 and HKUST-1 are extremely sensitive to the synthesis parameters explored in this study.
Co-reporter:Andreas Sonnauer, Norbert Stock
Solid State Sciences 2009 Volume 11(Issue 2) pp:358-363
Publication Date(Web):February 2009
DOI:10.1016/j.solidstatesciences.2008.09.002
Using the polyfunctional ligand 2-phosphonethanesulfonic acid (H3L) a high-throughput (HT) study was started for the systematic investigation of the system SrCl2/H3L/NaOH/H2O. The HT experiment comprising 48 individual reactions were performed to systematically investigate the influence of pH of the starting mixture as well as the molar ratio Sr2+:H3L. Two new compounds SrH(O3P–C2H4–SO3) (1) and Sr3(O3P–C2H4–SO3)2(H2O)2 (2) were obtained and structurally characterized by single-crystal X-ray diffraction. The reaction products synthesized under hydrothermal conditions always contain traces of SrSO4, which are due to the decomposition of small amounts of the ligand. While compound 2 could only be obtained under hydrothermal conditions, the synthesis of 1 could be accomplished under milder reaction conditions and a reaction scale-up could be performed. Compound 1 crystallizes in a monoclinic system with space group C2/c (no. 15), a = 534.73(11) pm, b = 1648.7(3) pm, c = 825.43(17) pm, β = 105.34(3)°, V = 701.8(2)–106 pm3, Z = 4, R1 = 0.0268, and wR2 = 0.0642 for I > 2σ(I). Compound 2 crystallizes in a triclinic system with space group P-1 (no. 2), a = 700.97(14) pm, b = 1008.5(2) pm, c = 1274.8(3) pm, α = 97.63(3)°, β = 92.03(3)°, γ = 92.03(3)°, V = 843.7(3)–106 pm3, Z = 2, R1 = 0.0360, and wR2 = 0.0896 for I > 2σ(I). In the structure of compound 1 the phosphorous and sulfur atoms cannot be distinguished due to identical crystallographic positions. Thus, an averaged structure was obtained which is built up by edge-sharing SrO8 polyhedra that form infinite M–O–M chains. Compound 2 contains corner-, edge-, and face-sharing SrO8 polyhedra which form inorganic M–O–M layers. These M–O–M chains (1) and layers (2) are connected to a three-dimensional network by the –CH2CH2– group of the ligand, respectively. Additional characterization by thermogravimetric analysis and IR-spectroscopy for compound 1 is also presented.
Co-reporter:Andreas Sonnauer;Frank Hoffmann Dr.;Michael Fröba Dr.;Lorenz Kienle Dr.;Viola Duppel;Matthias Thommes Dr.;Christian Serre;Gérard Férey Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 21) pp:3791-3794
Publication Date(Web):
DOI:10.1002/anie.200805980
Co-reporter:Tim Ahnfeldt;Nathalie Guillou Dr.;Daniel Gunzelmann;Irene Margiolaki Dr.;Thierry Loiseau Dr.;Gérard Férey Dr.;Jürgen Senker Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 28) pp:5163-5166
Publication Date(Web):
DOI:10.1002/anie.200901409
Co-reporter:Andreas Sonnauer;Frank Hoffmann Dr.;Michael Fröba Dr.;Lorenz Kienle Dr.;Viola Duppel;Matthias Thommes Dr.;Christian Serre;Gérard Férey Dr. Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/anie.200990107
Co-reporter:Andreas Sonnauer;Frank Hoffmann Dr.;Michael Fröba Dr.;Lorenz Kienle Dr.;Viola Duppel;Matthias Thommes Dr.;Christian Serre;Gérard Férey Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/ange.200990109
Co-reporter:Tim Ahnfeldt;Nathalie Guillou Dr.;Daniel Gunzelmann;Irene Margiolaki Dr.;Thierry Loiseau Dr.;Gérard Férey Dr.;Jürgen Senker Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 28) pp:5265-5268
Publication Date(Web):
DOI:10.1002/ange.200901409
Co-reporter:Andreas Sonnauer;Frank Hoffmann Dr.;Michael Fröba Dr.;Lorenz Kienle Dr.;Viola Duppel;Matthias Thommes Dr.;Christian Serre;Gérard Férey Dr. Dr.
Angewandte Chemie 2009 Volume 121( Issue 21) pp:3849-3852
Publication Date(Web):
DOI:10.1002/ange.200805980
Co-reporter:Andreas Sonnauer
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 32) pp:5038-5045
Publication Date(Web):
DOI:10.1002/ejic.200800315
Abstract
The polyfunctional ligand 2-phosphonoethanesulfonic acid, H2O3P–C2H4–SO3H (H3L), was used in a high-throughput (HT) investigation of a new class of compounds, the copper phosphonatosulfonates. An extensive HT study comprising 288 individual hydrothermal reactions was performed to systematically investigate the influence of temperature, pH, and molar ratio of Cu2+/H3L in the reaction system Cu(NO3)2/H3L/NaOH/H2O/temperature. The HT investigation led to five new compounds Cu2[(O3P–C2H4–SO3)(OH)(H2O)](H2O) (1), Cu2.5(O3P–C2H4–SO3)(OH)2 (2), Cu1.5[(O3P–C2H4–SO3)(H2O)]·H2O (3), Cu2[(O3P–C2H4–SO3)(OH)(H2O)2]·3H2O (4), and NaCu(O3P–C2H4–SO3)(H2O)3 (5). Their fields of formation were established unequivocally and from the large amount of data reaction trends were extracted. Furthermore, a new compound Cu1.5(O3P–C2H4–SO3)(H2O) (6) was synthesized under hydrothermal reaction conditions in a glass reactor. For compounds 1, 2, and 6 crystal structures were determined by single-crystal X-ray diffraction. The compounds exhibit a large structural variety. Thus, CuO4, CuO5, and CuO6 units are observed. Corner-, edge- as well as face-sharing polyhedra form chains, layers, or Cu3O12 clusters that are connected by the –CH2CH2– group of the ligand. Thermogravimetric investigations, magnetic measurements, IR spectra as well as chemical analyses of compounds 1, 3, 4, 5, and 6 are also presented.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Sebastian Bauer, Thomas Bein, Norbert Stock
Solid State Sciences 2008 Volume 10(Issue 7) pp:837-846
Publication Date(Web):July 2008
DOI:10.1016/j.solidstatesciences.2007.10.028
High-throughput (HT) methods in materials synthesis enable fast and systematic investigations of parameter space – compositional as well as process parameters – while consuming only small amounts of starting materials. We have developed a new work-up tool, a 48-parallel-filtration device, which was integrated into our HT methodology for the investigation of solvothermal reactions. Employing HT methods, we have studied the system CdCl2/(H2O3PCH2)2N–CH2C6H4–COOH (H5L)/NaOH leading to the discovery of four new compounds Cd[(HO3PCH2)2N(H)–CH2C6H4–COOH]2 (1), Cd(H2O)[H(O3PCH2)2N(H)–CH2C6H4–COOH] (2), Cd2[(O3PCH2)2N–CH2C6H4–COOH]·3H2O (3), and Cd3(OH)[(O3PCH2)2N–CH2C6H4–COO]·4.5H2O (4). The structures of 1 and 2 could be elucidated from laboratory X-ray powder diffraction data. All four title compounds were characterized using XRD, IR spectroscopy, as well as elemental, EDX, and thermogravimetric analyses. The pH of the starting mixture has a decisive influence on the product formation. Increasing amounts of NaOH lead to a gradual deprotonation of H5L and therefore an increasing molar ratio of Cd2+:ligand in the reaction products.High-throughput methods incorporating solvothermal reaction conditions permit the fast and systematic investigation of the system CdCl2/(H2O3PCH2)2N–CH2C6H4–COOH (H5L)/NaOH. The effect of the pH in the starting mixture was studied, leading to the formation of four new inorganic–organic compounds. Structural elucidations confirm that H5L favors the formation of layered compounds with zipper-like connection of metal phosphonate layers.
Co-reporter:Andreas Sonnauer, Norbert Stock
Journal of Solid State Chemistry 2008 Volume 181(Issue 3) pp:473-479
Publication Date(Web):March 2008
DOI:10.1016/j.jssc.2007.12.003
Co-reporter:Andreas Sonnauer, Norbert Stock
Journal of Solid State Chemistry 2008 Volume 181(Issue 11) pp:3065-3070
Publication Date(Web):November 2008
DOI:10.1016/j.jssc.2008.08.006
Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H2O3P–C2H4–SO3H (H3L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O3P–C2H4–SO3) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal structure was determined by single-crystal X-ray diffraction. The compounds contain isolated slightly distorted LnO6 octahedra that are connected by the phosphonate and sulfonate groups into a three-dimensional framework. Thermogravimetric investigations demonstrate the high thermal stability of the compounds up to 460 °C.A high-throughput and microwave investigation of the System LnX3/H2O3P–C2H4–SO3/NaOH/H2O led to six new compounds Ln(O3P–C2H4–SO3) with Ln=Ho, Er, Tm, Yb, Lu, Y.
Co-reporter:Sebastian Bauer Professor
Chemie in unserer Zeit 2008 Volume 42( Issue 1) pp:12-19
Publication Date(Web):
DOI:10.1002/ciuz.200800434
Abstract
MOFs (metal-organic frameworks) gehören zur Klasse der anorganisch-organischen Gerüstverbindungen. Sie sind hochkristallin und bestechen durch ihren modularen Aufbau aus Metallionen, Metall-Sauerstoff-Clustern, -Ketten oder -Schichten, die über funktionalisierbare organische Linker zu porösen dreidimensionalen Gerüsten verknüpft sind. Die Poren stehen für zahlreiche Anwendungen zur Verfügung und können mit Hilfe des Prinzips der isoretikulären Synthese bezüglich ihrer Größe und Polarität gezielt verändert und damit für spezielle Anwendungen maßgeschneidert werden. MOFs stellen eine neue Klasse poröser kristalliner Verbindungen dar. Aufgrund zahlreicher potentieller Anwendungen z.B. zur Gasspeicherung, in der Katalyse, als Nanoreaktoren oder bei der Wirkstofffreisetzung und wegen ihrer teilweise ungewöhnlichen Eigenschaften sind sie sowohl für die Industrie als auch für die universitäre Forschung von großem Interesse.
MOFs (metal-organic frameworks) have developed into an important class of materials. This is due to their potential application in the fields of catalysis, gas storage, nanoreactors, or drug release. MOFs are comprised of isolated metal ions or metal-oxygen clusters, chains or layers, which are connected via organic linkers to form three-dimensional frameworks of outstanding porosity. Owing to their modular assembly, the pores of MOFs can be tailored using functionalized linkers, following the principle of reticular chemistry.
Co-reporter:Sebastian Bauer, Norbert Stock
Journal of Solid State Chemistry 2007 Volume 180(Issue 11) pp:3111-3120
Publication Date(Web):November 2007
DOI:10.1016/j.jssc.2007.08.026
A new ligand, 5-diethylphosphonoisophthalic acid ((HOOC)2C6H3-PO3(C2H5)2, H2Et2L), for the hydrothermal synthesis of inorganic–organic hybrid compounds was prepared and characterized by NMR-spectroscopy. Its in situ hydrolysis leads to the corresponding 5-phosphonoisophthalic acid ((HOOC)2C6H3-PO3H2, H4L). Applying high-throughput methods, different di- and trivalent metal salts for the synthesis of crystalline metal phosphonates based on H2Et2L have been screened. From the resulting discovery library, single-crystals of four new compounds, [Sm2(H2O)4(H(OOC)2C6H3-PO3)2]·2H2O (1), [Cu3(H2O)(H(OOC)2C6H3-PO3)2]·2H2O (2), Ca2(H2O)[H(OOC)2C6H3-PO3H]2 (3), and Ba2(H2O)3(OOC)2C6H3-PO3 (4), have been isolated. The single-crystal structure determination of the title compounds shows H4L to be a versatile ligand, exhibiting different types of coordination modes between the functional groups and the metal ions. A comparison of the structural features of the title compounds shows a varying degree of M–O–M connectivities. Thus, isolated metal–oxygen clusters (compounds 1 and 2), infinite M–O–M chains (compound 3), and infinite M–O–M layers (compound 4) are observed. The title compounds 1, 2, and 3 were further characterized by IR-spectroscopy, TG-, EDX-, and elemental chemical analysis.Applying high-throughput methods, the new ligand 5-diethylphosphonoisophtalic acid, (HOOC)2C6H3-PO3(C2H5)2 (H2Et2L), was reacted with several di- and trivalent metal salts under hydrothermal conditions. Single-crystals of four new inorganic–organic hybrid compounds were isolated from the discovery library. The single-crystal structure analysis shows a varying M–O–M connectivity.
Co-reporter:Sebastian Bauer Dr.
Chemie in unserer Zeit 2007 Volume 41(Issue 5) pp:
Publication Date(Web):28 SEP 2007
DOI:10.1002/ciuz.200700404
Hochdurchsatz-Methoden zeichnen sich gegenüber konventionellen Methoden durch eine größere Effizienz aus. Mittlerweile steht im Bereich der Anorganischen Festkörperchemie und der Materialwissenschaften eine Vielzahl von Werkzeugen zur Verfügung, um die Entdeckung und Optimierung von Materialien durch Verwendung von HD-Methoden schneller voranzutreiben. Für alle Arbeitstechniken gilt: Das Ausmaß der Automatisierung, Parallelisierung und Miniaturisierung sowie die Integration aller Einzelschritte in einen Gesamtprozess bestimmt die Effizienz einer HD-Methodik. Durch eine systematische Untersuchung des Parameterraumes und durch sorgfältige Datenevaluierung (möglichst Software-gestützt) können Trends gefunden werden, die zu einem besseren Verständnis der untersuchten Systeme beitragen.
Der vorgestellte Ansatz zur HD-Untersuchung von Solvothermalreaktionen erlaubt die automatisierte Synthese und Charakterisierung von bis zu 48 Produkten ohne die Proben einzeln manipulieren zu müssen. Der geringe Reagenzienverbrauch zusammen mit der Möglichkeit, die Reaktionen unter identischen Prozessparametern (Temperatur, Zeit, Druck, usw.) durchführen zu können, ermöglichen die systematische Untersuchung eines größeren Parameterraumes. An Hand zahlreicher Beispiele haben wir das Potential von Hochdurchsatz- Methoden bei der Entdeckung neuer Verbindungen, der Optimierung von Reaktionen, beim Auffinden von Reaktionstrends sowie der Untersuchung des Einflusses von Prozessparametern gezeigt.
High-throughput (HT) methods applied to materials discovery have attracted much attention over the last few years because they permit a fast and efficient investigation of parameter space while consuming only small amounts of starting materials. Nowadays, many different HT techniques in solid state science are employed in order to accelerate the discovery and optimization of materials. The degree of parallelisation, automation, and miniaturization determines the efficiency of a HT methodology. Systematic investigation of parameter space and careful data analysis allow the identification of reaction trends and may give important guidance in better understanding of reaction systems.
The described HT methodology for solvothermal reactions allows the systematic investigation of 48 different hydrothermal reactions at a time. The methodology includes automatic dispensing of solids and liquids, followed by homogenization, pH measurement, synthesis, isolation, washing as well as automated phase analysis by X-ray diffraction without the manipulation of individual samples.
The focus of this article is on the application of HT methods in the investigation of the parameter space in solid state sciences. Based on selected examples, the power of HT methods in the discovery of new compounds, the optimization of reactions, the identification of reaction trends, as well as the investigation of the influence of process parameters is described. The large amount of data obtained in a short time leads to an improvement towards the understanding of the role that synthesis and process parameters play in the formation of compounds and materials.
Co-reporter:Sebastian Bauer Dr.
Angewandte Chemie 2007 Volume 119(Issue 36) pp:
Publication Date(Web):3 AUG 2007
DOI:10.1002/ange.200701575
Fünf neue Cd-Phosphonate wurden bei der systematischen Untersuchung des Einflusses der Reaktionstemperatur neben der Zusammensetzung und dem pH-Wert gemäß dem Titelvorgehen auf die Synthese organisch-anorganischer Hybridverbindungen im CdCl2/H5L/NaOH-System entdeckt. Im erhaltenen Kristallisationsdiagramm (siehe Bild) steht jede Farbe für eine Phase.
Co-reporter:Sebastian Bauer Dr.
Angewandte Chemie International Edition 2007 Volume 46(Issue 36) pp:
Publication Date(Web):3 AUG 2007
DOI:10.1002/anie.200701575
Five new Cd phosphonates were discovered in a systematic investigation of the influence of the reaction temperature besides composition and pH value on the synthesis of inorganic–organic hybrid compounds in the CdCl2/H5L/NaOH system, which was achieved by the title procedure. In the resulting crystallization diagram (see picture), each color corresponds to a different phase.
Co-reporter:Enrica Biemmi, Thomas Bein, Norbert Stock
Solid State Sciences 2006 Volume 8(3–4) pp:363-370
Publication Date(Web):March–April 2006
DOI:10.1016/j.solidstatesciences.2006.02.025
A new open-framework zinc terephthalate (H2NEt2)2[Zn3(BDC)4]⋅3DEF (BDC = 1,4-benzendicarboxylate, DEF=N,N′DEF=N,N′-diethylformamide) was obtained under slightly acidic condition by reacting 1,4-benzendicarboxylic acid (H2BDC) with ZnO in a DEF solution.The structure was obtained by single crystal X-ray diffraction and consists of trimetallic zinc building units, that are interconnected by eight BDC units each (crystal data: monoclinic, C2/cC2/c, a=3337.24(5)a=3337.24(5), b=983.17(2)b=983.17(2), c=1819.67(2) pmc=1819.67(2) pm, β=92.455(1)○β=92.455(1)○, V=5965.0(2)×106 pm3V=5965.0(2)×106 pm3, Z=4Z=4, R1=0.0395R1=0.0395, wR2=0.0843wR2=0.0843 for 4533 reflections I>2σ(I)I>2σ(I)). Six BDC ions together with the trimetallic zinc units form a two-dimensional (3,6)(3,6)-net while the other two BDC unit pillar these layers. Thus a three-dimensional anionic framework with a 2D pore system is formed. The pore space is occupied by solvent molecules (DEF) and diethylammonium ions, produced by in situ hydrolysis of DEF. These are interconnected as well as connected to the framework by hydrogen-bonds. The TG investigation in combination with powder X-ray diffraction and vibrational-spectroscopy show a two-step loss of the pore filling molecules as well as one H2BDC molecule leading to crystalline phases which are stable up to 250 and 400 °C, respectively. In addition, 13C MAS-NMR data of the title compound is presented.
Co-reporter:Sebastian Bauer, Thomas Bein, Norbert Stock
Journal of Solid State Chemistry 2006 Volume 179(Issue 1) pp:145-155
Publication Date(Web):January 2006
DOI:10.1016/j.jssc.2005.10.008
The phosphonocarboxylic acid H(HO3PCH2)2NH-CH2C6H4-COOH (H5L) was synthesized and characterized by NMR- and IR-spectroscopy, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Reactions of H5L with samarium(III) chloride and calcium(II) chloride resulted in three new compounds, Sm[(O3PCH2)2NH-CH2C6H4-COOH]·H2O (1), Ca[H(O3PCH2)2NH-CH2C6H4-COOH]·H2O (2), and Ca[(HO3PCH2)2NH-CH2C6H4-COOH]2·4H2O (3). The single-crystal structure determination of the title compounds reveals that in H5L as well as in compounds 1, 2, and 3 zwitterions are present. Within the M–O building units of the metal phosphonates we observed a different degree of dimensionality, depending on the oxidation state of the metal ion and the synthesis conditions. In 1, one-dimensional chains of edge-sharing SmO8 polyhedra are observed while in 2, isolated units of edge-sharing CaO6 octahedra and in 3 isolated CaO6 octahedra are observed. However, looking at the organic part, the rigid phenyl carboxylic acid moieties arrange in a “zipper-like” fashion and hydrogen bonding plays an important role in the stabilization of the crystal structure. The title compounds were further characterized by IR spectroscopy and TG analysis. Additionally, the thermal stability of 1 was investigated by temperature-dependent X-ray diffraction.Hydrothermal reactions of the phosphonocarboxylic acid H(HO3PCH2)2NH-CH2C6H4-COOH with Sm3+ and Ca2+ salts has led to three new inorganic–organic hybrid compounds. All crystal structures contain phosphonate zwitterions and have a layer-like arrangement. The rigid organic groups arrange in a “zipper-like” fashion and hydrogen bonding plays an important role in the stabilization of the crystal structures.
Co-reporter:N. Stock Dr.;S. Bauer Dipl. Chem.
Chemie Ingenieur Technik 2006 Volume 78(Issue 9) pp:
Publication Date(Web):6 SEP 2006
DOI:10.1002/cite.200650460
Co-reporter:Norbert Stock and Thomas Bein
Journal of Materials Chemistry A 2005 vol. 15(Issue 13) pp:1384-1391
Publication Date(Web):01 Feb 2005
DOI:10.1039/B413318H
The phosphonocarboxylic acid H2O3PCH2–C6H5–COOH has been employed in the synthesis of several metal carboxyarylphosphonates under hydrothermal conditions. The system MnCl2/H2O3PCH2–C6H4–COOH/NaOH was investigated in detail using high-throughput methods and reaction trends as well as the fields of formation could be identified. Three new compounds Mn[HO3PCH2–C6H4–COOH]2·2H2O (1) Mn[O3PCH2–C6H4–COOH]·H2O (2) and Mn2(OH)[O3PCH2–C6H4–COO]·2H2O (3) were obtained and compounds 1 and 2 could be isolated as single crystals suitable for single crystal X-ray diffraction. Using similar reaction conditions the corresponding Cu and Cd compounds of 1 and 2
(Cu[HO3PCH2–C6H4–COOH]2·2H2O (4), Cd[O3PCH2–C6H4–COOH]·H2O (5)) were obtained and structurally characterized. The results of the high-throughput study demonstrate the effect of the gradual deprotonation of the phosphonocarboxylic acid on the structure of the resulting compounds. Compounds 1 and 4 are formed under more acidic conditions and therefore the phosphonic acid group is mono-protonated. The structure is built of four-membered rings of alternating corner-sharing MO6 and O3PC polyhedra that are linked to form chains. These chains are connected through O–H⋯O hydrogen bonds to form a three-dimensional framework. In compounds 2 and 5 formed under more basic conditions the phosphonic acid group is fully deprotonated and, due to the additional coordinating O atom, a layered structure composed of MO6 and O3PC polyhedra is formed. These layers are held together by O–H⋯O hydrogen bonds involving the carboxylic acid groups. Based on spectroscopic, thermogravimetric and EDX-analysis data, compound 3 has been characterized as Mn2(OH)[O3PCH2–C6H4–COO]·2H2O where the phosphonocarboxylic acid is fully deprotonated.
Co-reporter:Paul M. Forster, Norbert Stock,Anthony K. Cheetham
Angewandte Chemie International Edition 2005 44(46) pp:7608-7611
Publication Date(Web):
DOI:10.1002/anie.200501766
Co-reporter:Sebastian Bauer ; Christian Serre ; Thomas Devic ; Patricia Horcajada ; Jérôme Marrot ; Gérard Férey
Inorganic Chemistry () pp:
Publication Date(Web):August 6, 2008
DOI:10.1021/ic800538r
Through the use of high-throughput methods, solvothermal reactions of FeCl3 and 2-aminoterephthalic acid in protic as well as aprotic reaction media were systematically studied. Thus, the fields of formation of the isoreticular structures of MIL-53, MIL-88, and MIL-101 based on Fe(III) and aminoterephthalate could be identified for the first time. The resulting 3D framework materials with amino-functionalized pores have been characterized using X-ray diffraction; IR spectroscopy; and thermogravimetric, elemental, and energy dispersive X-ray analysis. Due to the applied high-throughput method, a high density of information was obtained in a short period of time, which allows the extraction of important reaction trends and contributes to a better understanding of the role of compositional as well as process parameters in the synthesis of inorganic−organic hybrid materials. We have found that the nature of the reaction medium has the most profound impact on structure formation. Furthermore, the concentration of the starting mixture (i.e., the solvent content) and the temperature have also been identified as key parameters for the formation of the different hybrid phases.
Co-reporter:Antje Modrow, Dordaneh Zargarani, Rainer Herges and Norbert Stock
Dalton Transactions 2012 - vol. 41(Issue 28) pp:NaN8696-8696
Publication Date(Web):2012/05/21
DOI:10.1039/C2DT30672G
For the first time an azo functionality was covalently introduced into a MOF by post-synthetic modification. The reaction of Cr-MIL-101-NH2 with p-phenylazobenzoylchloride (1) and 4-(phenylazo)phenylisocyanate (2) as the reactants led to the compounds Cr-MIL-101_amide and Cr-MIL-101_urea, with the azo groups protruding into the mesoporous cages. XRPD and N2 sorption measurements confirm the intactness of the framework and the successful covalent modification was proven by IR- and NMR-spectroscopy. Furthermore, cis/trans isomerisation upon irradiation with light was demonstrated by UV/Vis spectroscopy. More distinct changes in the UV/Vis spectra were observed for Cr-MIL-101_amide compared to Cr-MIL-101_urea, while the degree of functionalization, i.e. the number of reacted NH2-groups, seems to have a less pronounced effect. The variation of the sorption properties due to the cis/trans isomerisation was proven by methane adsorption measurements.
Co-reporter:Helge Reinsch, Steve Waitschat and Norbert Stock
Dalton Transactions 2013 - vol. 42(Issue 14) pp:NaN4847-4847
Publication Date(Web):2013/01/14
DOI:10.1039/C3DT32355B
The metal–organic framework compound [Al(OH)(BDC-Br)] (1) (BDC-Br2− = 5-bromo-1,3-benzenedicarboxylate) denoted CAU-10-Br was synthesised under solvothermal reaction conditions. Its structure was successfully refined by Rietveld methods. The framework is based on the connection of infinite helical chains of cis-corner-sharing AlO6-polyhedra via BDC-Br2− ions. Thus non-intersecting parallel channels are formed, each periodically varying in diameter between 1.1 and 6.6 Å. Nevertheless 1 adsorbs CO2 at 298 K, while it is non-porous towards H2 and N2 at 77 K. Employing high-throughput (HT) methods we identified synthesis conditions that lead to the formation of mixed-linker MOFs with CAU-10 topology. Starting with a molar ratio H2BDC:H2BDC-Br = 3:1 we established a synthesis procedure for the partially bromo-functionalised mixed-linker-MOF [Al(OH)(BDC)0.8(BDC-Br)0.2] (2) denoted as CAU-10-H/Br. Starting with a molar ratio H2BDC-NH2:H2BDC-NO2 = 1:1 the partially NO2- and NH2-functionalised mixed-linker MOF [Al(OH)(BDC-NO2)0.55(BDC-NH2)0.23(BDC-NHCHO)0.22] (3) denoted as CAU-10-NO2/NH2 was synthesised, in which the NH2-groups were found to be partially formylated. The partial bromo-functionalisation in CAU-10-H/Br (2) leads to a lower sorption capacity in comparison with the parent structure CAU-10-H, while the pore accessibility is comparable. The incorporation of NO2-, NH2- and NHCHO-groups in CAU-10-NO2/NH2 (3) does not only affect the accessibility of the pores for N2, but results also in an increased capacity for H2 and CO2 in comparison with the parent structure CAU-10-NO2. The reproducibility of the synthesis procedures was tested regarding the composition of the MOFs and the resulting gas sorption properties. In 2 a molar fraction of (BDC)2− = 80 ± 2% is found, while in 3 a molar fraction of (BDC-NO2)2− = 55 ± 2% is observed. Starting from the molar ratio H2BDC:H2BDC-CH3 = 1:1 mixed linker MOFs denoted as CAU-10-H/CH3 (4) were also obtained. In contrast to 2 and 3 the molar ratios of BDC2−/BDC-CH32− and especially the sorption properties differ substantially for every batch. The compounds were further characterised by X-ray powder diffraction, thermogravimetric/elemental analysis, NMR/Vis/IR-spectroscopy, and gas sorption measurements.
Co-reporter:T. Homburg, C. Hartwig, H. Reinsch, M. Wark and N. Stock
Dalton Transactions 2016 - vol. 45(Issue 38) pp:NaN15047-15047
Publication Date(Web):2016/08/17
DOI:10.1039/C6DT03048C
The structures of the imidazole loaded derivatives of Al-MIL-53 [Al(OH)(1,4-BDC-(CH3)x)] (x = 0, 1, 2) and CAU-11 ([Al(OH)(SDBA)]) (1,4-H2BDC = terephthalic acid; H2SDBA = 4,4′-sulfonyldibenzoic acid) were determined from powder X-ray diffraction data. Impedance spectroscopy measurements were carried out to evaluate their proton conductivities under anhydrous conditions at temperatures up to 110 °C. In Al-MIL-53-(CH3)x_HIm (x = 0, 1, 2) the formation of hydrogen bonds between the framework and the guest molecules results in a decrease in proton conductivity (x0 = 1.7 × 10−6, x1 = 1.9 × 10−8 and x2 = 1.7 × 10−9 S cm−1 at 110 °C and Eact = 0.42, 0.41 and 0.46 eV, for 0, 1 and 2 CH3-groups, respectively). The highest conductivity has been measured for CAU-11_HIm with 3.0 × 10−4 S cm−1 at 110 °C (Eact = 0.19 eV), where no host–guest hydrogen bonding interactions are observed.
Co-reporter:M. Lammert, C. Glißmann and N. Stock
Dalton Transactions 2017 - vol. 46(Issue 8) pp:NaN2429-2429
Publication Date(Web):2017/01/26
DOI:10.1039/C7DT00259A
A series of solid solutions of bimetallic Ce/Zr-UiO-66 and -MOF-808 compounds with a varying ratio of Ce4+ to Zr4+ were obtained under mild reaction conditions within 15 min. The lattice parameters of the mixed-metal compounds are in accordance with Vegard's law. Samples with Ce ≤20 at% exhibit an enhanced thermal stability, better resistance against acids and smaller particle sizes.
Co-reporter:Antje Modrow, Dordaneh Zargarani, Rainer Herges and Norbert Stock
Dalton Transactions 2011 - vol. 40(Issue 16) pp:NaN4222-4222
Publication Date(Web):2011/03/10
DOI:10.1039/C0DT01629B
We synthesized a porous twofold interpenetrated MOF [Zn2(NDC)2(1)] (coined CAU-5) using 3-azo-phenyl-4,4′-bipyridine (1), 2,6-naphthalenedicarboxylic acid, and Zn(NO3)2·6H2O. The azo-functionality protrudes into the pores, and can be switched, by irradiation with UV light (365 nm), from the thermodynamically stable trans-isomer to the cis-isomer. Back-switching was achieved thermally and with an irradiation wavelength of λmax = 440 nm.
Co-reporter:Helge Reinsch, Bartosz Marszałek, Julia Wack, Jürgen Senker, Barbara Gil and Norbert Stock
Chemical Communications 2012 - vol. 48(Issue 76) pp:NaN9488-9488
Publication Date(Web):2012/08/08
DOI:10.1039/C2CC34909D
The new Al-based metal–organic framework [Al13(OH)27(H2O)6(BDC-NH2)3Cl6(C3H7OH)6] denoted CAU-6 (CAU = Christian-Albrechts-Universität) was solvothermally synthesized in 2-propanol and was thoroughly characterized. The framework structure exhibits a unique column-shaped inorganic building unit, which is based on stacked, corner-sharing Al13-clusters. The compound exhibits unprecedented hydrophilicity for metal–organic frameworks.
Co-reporter:Shyam Biswas, Michael Maes, Amarajothi Dhakshinamoorthy, Mark Feyand, Dirk E. De Vos, Hermenegildo Garcia and Norbert Stock
Journal of Materials Chemistry A 2012 - vol. 22(Issue 20) pp:NaN10209-10209
Publication Date(Web):2012/02/03
DOI:10.1039/C2JM15592C
Two isostructural microporous metal–organic frameworks [Co(DMA)6]3[(Co4Cl)3(BTT)8(H2O)12]2·12H2O (BTT3− = 1,3,5-benzenetristetrazolate; DMA = N,N′-dimethylacetamide) (1) and [Cd(DMF)6]3[(Cd4Cl)3(BTT)8(H2O)12]2·14H2O·4DMF (DMF = N,N′-dimethylformamide) (2) were synthesized under solvothermal conditions. The structures of both compounds were determined by single-crystal X-ray diffraction data. Each compound adopts a porous three-dimensional framework consisting of square-planar [M4Cl]7+ (M2+ = Co, 1; Cd, 2) units interconnected by triangular tritopic BTT3− bridging ligands to give an anionic (3,8)-connected “Moravia” net. Phase purity of the compounds was confirmed by X-ray powder diffraction (XRPD), IR spectroscopy, thermogravimetric (TG) and elemental analysis. TGA and temperature-dependent XRPD (TDXRPD) experiments indicate a moderate thermal stability up to 350 and 300 °C, respectively. Guest exchange followed by heating led to microporous solids with coordinatively unsaturated metal sites. These unsaturated metal sites create opportunities in adsorptive and catalytic applications. These have been probed by the selective removal of sulfur compounds from fuel feeds as well as the catalytic ring opening of styrene oxide and the oxidation of several cycloalkanes and benzyl compounds.
Co-reporter:Lars-Hendrik Schilling and Norbert Stock
Dalton Transactions 2014 - vol. 43(Issue 2) pp:NaN422-422
Publication Date(Web):2013/10/31
DOI:10.1039/C3DT52576G
High-throughput reactions of aqueous solutions of 4-(phosphonomethyl)benzoic acid (H3PMBC) with metal salts were carried out using, for the first time, ultrasonication as well as the previously described conventional heating. On screening the influence of 12 divalent metal ions, two new compounds ([Ca(H2O)2(H2PMBC)2] and [Ni(H2O)4(H2PMBC)2]) were discovered. Their formation fields were established by systematically studying the systems Ni2+ or Ca2+/H3PMBC/KOH. Both compounds crystallise in the space group P ([Ca(H2O)2(H2PMBC)2]: a = 4.6806(9) Å, b = 6.1340(12) Å, c = 17.932(4) Å, α = 83.84(3)°, β = 89.03(3)°, γ = 85.65(3)°; [Ni(H2O)4(H2PMBC)2]: a = 4.7713(10) Å, b = 6.8621(14) Å, c = 16.598(3) Å, α = 83.42(3)°, β = 89.71(3)°, γ = 83.50(3)°) and contain MO6-octahedra linked to form chains by hydrogen bonded (H2PMBC−)2-dimers formed between the carboxylate groups. The formation of [Ni(H2O)4(H2PMBC)2] was studied by in situ EDXRD and in situ IR spectroscopy. The increased formation rate of [Ni(H2O)4(H2PMBC)2] under ultrasonic irradiation as compared to conventional heating could be unequivocally attributed to the faster dissolution of the ligand H3PMBC.
Co-reporter:Martin Lammert, Michael T. Wharmby, Simon Smolders, Bart Bueken, Alexandra Lieb, Kirill A. Lomachenko, Dirk De Vos and Norbert Stock
Chemical Communications 2015 - vol. 51(Issue 63) pp:NaN12581-12581
Publication Date(Web):2015/07/02
DOI:10.1039/C5CC02606G
A series of nine Ce(IV)-based metal organic frameworks with the UiO-66 structure containing linker molecules of different sizes and functionalities were obtained under mild synthesis conditions and short reaction times. Thermal and chemical stabilities were determined and a Ce-UiO-66-BDC/TEMPO system was successfully employed for the aerobic oxidation of benzyl alcohol.
Co-reporter:Helge Reinsch and Norbert Stock
Dalton Transactions 2017 - vol. 46(Issue 26) pp:NaN8349-8349
Publication Date(Web):2017/06/05
DOI:10.1039/C7DT01115F
This perspective highlights some studies and insights in the synthesis of metal–organic frameworks (MOFs) in a brief and comprehensive manner. The understanding of the synthesis procedures investigated by in and ex situ methods is of special interest since knowledge on the nucleation and crystallisation mechanism will ideally lead to an improved control over product formation. The prospective developments associated with the manufacturing of such materials (or devices consisting thereof) are discussed as well. A major challenge is the adjustment of the synthesis conditions to yield quantities suitable for real life applications. Last but not least, vast opportunities are yet to be explored involving the synthesis of both known and novel compounds. Thus the crucial points involving the synthesis of MOFs summarized in this perspective are rationalisation, application and exploration. For each subtopic we have also attempted to anticipate future challenges and developments.
Co-reporter:M. Köppen, O. Beyer, S. Wuttke, U. Lüning and N. Stock
Dalton Transactions 2017 - vol. 46(Issue 26) pp:NaN8663-8663
Publication Date(Web):2017/06/08
DOI:10.1039/C7DT01744H
Two new bismuth metal–organic frameworks (Bi-MOFs) were discovered using high throughput experiments employing bismuth(III) nitrate pentahydrate and triazine-2,4,6-triyl-tribenzoic acid (H3TATB). The reaction was carried out for long reaction times (∼5 d) in a water/DMF-mixture and resulted in the formation of [Bi2(O)(OH)(TATB)]·H2O (denoted as CAU-35). By switching to short reaction times and a methanol/DMF-mixture as the solvent, an analogue of CAU-7-BTB with the composition [Bi(TATB)]·DMF·6H2O (denoted as CAU-7-TATB) was obtained. The use of the amino-functionalised H3TATB linker (H3TATB-NH2) resulted in the formation of a functionalised porous Bi-MOF with the composition [Bi(TATB-NH2)]·5H2O·0.5DMF (CAU-7-TATB-NH2). The structures of CAU-35 and CAU-7-TATB were successfully solved and refined from the PXRD data. CAU-7-TATB-NH2 was post-synthetically modified using anhydrides (acetic anhydride and valeric anhydride), cyclic anhydrides (succinic anhydride and phthalic anhydride), and 1,3-propane sultone. The degree of conversion ranged from 33% to 79%.
Co-reporter:Helge Reinsch, Jannik Benecke, Martin Etter, Niclas Heidenreich and Norbert Stock
Dalton Transactions 2017 - vol. 46(Issue 5) pp:NaN1405-1405
Publication Date(Web):2017/01/05
DOI:10.1039/C6DT03998G
The intercalation of different pyrazines (pyrazine, methylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, trimethylpyrazine and tetramethylpyrazine) into the trans-1,4-cyclohexanedicarboxylate (CDC2−) based Al-MOF [Al(OH)(CDC)], denoted as CAU-13, was investigated. The adsorption of the guest molecules into the flexible MOF was carried out from an aqueous solution or via vapour phase adsorption, starting with the hydrated narrow-pore form of the framework [Al(OH)(O2C-C6H10-CO2)]·H2O (CAU-13-np). The obtained host–guest systems were characterised by thermogravimetry and vibrational spectroscopy and their crystal structures were elucidated using powder X-ray diffraction (PXRD) data. The crystal structures indicate that guest molecules forming hydrogen-bonds with the host framework (pyrazine, methylpyrazine and 2,5-dimethylpyrazine) induce a slight opening of the channels, resulting in a semi-open framework conformation (CAU-13-so). For the bulkier guests 2,3-dimethylpyrazine, trimethylpyrazine and tetramethylpyrazine, only van der Waals interactions can be observed between the host and the guest molecules and a large pore conformation is observed (CAU-13-lp). We carried out in situ PXRD studies using synchrotron radiation during the adsorption of the respective guest molecules from aqueous solutions with various concentrations and at different temperatures. In general, stronger host–guest interactions required milder adsorption conditions while harsher conditions nevertheless accelerated the conversion. The kinetic parameters for the intercalation of pyrazine indicate that the rate limiting step differs, depending on the intercalation temperature.
Co-reporter:M. Lammert, H. Reinsch, C. A. Murray, M. T. Wharmby, H. Terraschke and N. Stock
Dalton Transactions 2016 - vol. 45(Issue 47) pp:NaN18826-18826
Publication Date(Web):2016/11/08
DOI:10.1039/C6DT03852B
Two new MOFs denoted as M-CAU-24 (M = Zr, Ce) based on 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4TCPB) were obtained under mild reaction conditions within 15 min. The MOFs with composition [M6(μ3-O)4(μ3-OH)4(OH)4(H2O)4(TCPB)2] crystallise in the scu topology, a connectivity hitherto unreported for Zr-MOFs with tetracarboxylate linker molecules. Zr-CAU-24 exhibits UV/blue ligand-based luminescence.
Co-reporter:S. Waitschat, H. Reinsch and N. Stock
Chemical Communications 2016 - vol. 52(Issue 86) pp:NaN12701-12701
Publication Date(Web):2016/09/01
DOI:10.1039/C6CC06287C
A new, microporous Zr-MOF was obtained using 2,5-pyrazinedicarboxylic acid (H2PzDC). The linker leads to the formation of a new 1D inorganic building unit composed of μ-OH bridged {Zr6O4(OH4)} clusters which are arranged in a hexagonal array and connected by the PzDC2− ions. The structure was determined from powder X-ray diffraction data.
Co-reporter:Yan Meng, Guang-Hui Wang, Stephan Bernt, Norbert Stock and An-Hui Lu
Chemical Communications 2011 - vol. 47(Issue 37) pp:NaN10481-10481
Publication Date(Web):2011/08/19
DOI:10.1039/C1CC13699B
A crystal-like ordered microporous inorganic hybrid solid was prepared using silane functionalized Cr-MIL-101 (Si-MIL-101) as the precursor, via a surface coating reinforced framework strategy.
Co-reporter:Helge Reinsch, Mark Feyand, Tim Ahnfeldt and Norbert Stock
Dalton Transactions 2012 - vol. 41(Issue 14) pp:NaN4171-4171
Publication Date(Web):2012/01/30
DOI:10.1039/C2DT12005D
A new family of Al-based MOFs denoted as CAU-3 (CAU = Christian-Albrechts-Universität) was discovered in the solvothermal system Al3+/aryldicarboxylic acid/NaOH/methanol by applying high-throughput-methods. The three compounds reported in this article [Al2(OCH3)4BDC], [Al2(OCH3)4BDC-NH2] and[Al2(OCH3)4NDC] (BDC = 1,4-benzenedicarboxylate; NDC = 2,6-naphtalenedicarboxylate) are all based on the same unprecedented inorganic building unit [Al12(OCH3)24]12+, which is a dodecameric cyclic aluminium-methanolate-cluster. The material CAU-3-NDC was found to exhibit the highest surface area as well as the highest micropore volume of all Al-based MOFs reported until now.
Co-reporter:Stephan Bernt, Vincent Guillerm, Christian Serre and Norbert Stock
Chemical Communications 2011 - vol. 47(Issue 10) pp:NaN2840-2840
Publication Date(Web):2011/01/21
DOI:10.1039/C0CC04526H
For the first time, functionality has been covalently introduced into the Cr-MIL-101 network by post-synthetic modification of the terephthalate linker molecule through nitration. The nitro group was reduced and the amino group was reacted with ethyl isocyanate to yield the corresponding urea derivative.
Co-reporter:Helge Reinsch, Renjith S. Pillai, Renée Siegel, Jürgen Senker, Alexandra Lieb, Guillaume Maurin and Norbert Stock
Dalton Transactions 2016 - vol. 45(Issue 10) pp:NaN4186-4186
Publication Date(Web):2015/10/16
DOI:10.1039/C5DT03510D
The new aluminium based metal–organic framework [Al(OH)(O2C–C4H8–CO2)]·H2O denoted as Al-MIL-53-ADP-lp (lp stands for large pore) was synthesised under solvothermal conditions. This solid is an analogue of the archetypical aluminium terephthalate Al-MIL-53 based on the aliphatic single-chain linker molecule adipic acid (H2ADP, hexanedioic acid). In contrast to its aromatic counterparts, Al-MIL-53-ADP exhibits a structural breathing behaviour solely upon dehydration/rehydration. The crystal structure of the anhydrous compound denoted as Al-MIL-53-ADP-np (np stands for narrow pore) was determined by a combination of forcefield-based computations and Rietveld refinement of the powder X-ray diffraction data while the structure of the hydrated form Al-MIL-53-ADP-lp was derived computationally by a combination of force field based methods and Density Functional Theory calculations. Both structures were further supported by 1H, 13C and 27Al high-resolution NMR MAS 1D data coupled again with simulations. Al-MIL-53-ADP was further characterised by means of vibrational spectroscopy, elemental analysis, thermogravimetry and water vapour sorption.
Co-reporter:Mark Feyand, Christopher F. Seidler, Carsten Deiter, Andre Rothkirch, Alexandra Lieb, Michael Wark and Norbert Stock
Dalton Transactions 2013 - vol. 42(Issue 24) pp:NaN8770-8770
Publication Date(Web):2013/04/12
DOI:10.1039/C3DT50413A
A systematic study was carried out to investigate the influence of linker geometry, metal ionic radius as well as the nature of the counter ions on the structure formation of metal tetraphosphonates. Two tetraphosphonic acids p- and m-(H2O3PCH2)2N-CH2-C6H4-CH2-N(CH2PO3H2)2, six metal ions (Ca2+, Mn2+, Co2+, Ni2+, Zn2+, and Cd2+) and two different counter ions (Cl− and NO3−) were employed using high throughput methods. Microwave (MW)-assisted heating led to the discovery of ten new metal-phosphonates which crystallize in three different crystal structures. The combination of direct methods and force field calculations allowed us to establish the crystal structures. The counter ion and the ionic radii of the metal ions have a profound influence on the crystallinity and the formed crystal structure. All compounds were characterized in detail by thermogravimetric analyses, IR spectroscopy and magnetic susceptibility measurements. The proton conductivity of two selected compounds is also reported.
Co-reporter:N. Hermer and N. Stock
Dalton Transactions 2015 - vol. 44(Issue 8) pp:NaN3723-3723
Publication Date(Web):2015/01/27
DOI:10.1039/C4DT03698K
High throughput methods were employed in the discovery of [Cu3(PPT)(H2O)3]·10H2O (denoted CAU-14). The structure contains one-dimensional channels with a diameter of 9.4 Å. Thermal activation leads to the formation of uncoordinated metal sites and a high water uptake of 39.1 wt% was found.
Co-reporter:Steve Waitschat, Michael T. Wharmby and Norbert Stock
Dalton Transactions 2015 - vol. 44(Issue 24) pp:NaN11240-11240
Publication Date(Web):2015/05/15
DOI:10.1039/C5DT01100K
A continuous flow reactor was developed for the synthesis of porous metal–organic frameworks (MOFs) under mild reaction conditions. Commodity hardware was used to assemble the device, giving it a great degree of flexibility in its configuration. The use of paraffin to encapsulate reactions and also ultrasonic treatment were employed to prevent clogging of the reactor. Reactor design was optimised through studies of the synthesis of zirconium carboxylate framework UiO-66. Synthesis of the aluminium carboxylate CAU-13 was also performed, to demonstrate the versatility of the device. Finally the reactor was used to synthesise a new cadmium phosphonate framework, bearing the STA-12 network.
