Detailed structural characterization and photoluminescence properties of four new metal–organic frameworks (MOFs) based on zinc(II) or cadmium(II) metal ions, di- or tricarboxylic aromatic ligands, and bipyridyl-like elongated ancillary linkers, namely, {[Zn2(μ4-bdc)2(μ-pbptz)]·2DMF·3H2O}n (1), {[Cd(μ3-bdc)(μ-pbptz)]·3DMF}n (2), {[Cd3(μ5-btc)2(μ-pbptz)]·2DMF}n (3), and {[Zn2(μ-dhbdc)2(μ-pbptz)(DMF)4]·2DMF·H2O}n (4) (where bdc = benzene-1,4-dicarboxylato, btc = benzene-1,3,5-tricarboxylato, dhbdc = 2,5-dihydroxobenzene-1,4-dicarboxylato, pbptz = 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine, DMF = N,N-dimethylformamide) are reported. The occurrence of large accessible volumes and structural and topological diversity are a constant for crystal structures of these compounds, which is a result of the connectivity established among the metal-carboxylato building units formed in each case. Three-dimensional (3D) pcu frameworks of compounds 1 and 2 are built from the linkage of dimeric cores (established by the coordination of dicarboxylato bdc ligands) into two-dimensional networks that are further joined together by ancillary ligands, whereas the novel jcr7 topological 3D framework is achieved in 3 owing to the presence of the tricarboxylic btc ligand. Two-dimensional layers are generated in 4 given the bidentate coordination of both dhbdc and pbptz ligands. Interestingly, most crystal structures (3D frameworks of 1, 2, and 3) exhibit open architectures containing large solvent-occupied void systems that account for high relative void volumes. A deep analysis of the photophysical properties has been also accomplished for all compounds, confirming an overall blue emission under UV excitation in the steady state. Compound 3 is characterized with a strong phosphorescent emission that lasts a few seconds and is observed by the naked eye, which constitutes an infrequent photoluminescent behavior for metal–organic materials.

Isostructural dinuclear dysprosium and yttrium coordination compounds based on the 5-nitropicolinic carboxylate ligand were synthesized and characterized. The formation of these air-stable complexes is achieved via solvothermal routes employing water as the reaction solvent. The dysprosium-based complex exhibits single-molecule magnet behavior with frequency dependence of the out-of-phase susceptibility at zero direct-current field. High-resolution mass spectrometry (electrospray ionization) experiments and advanced NMR methods including diffusion NMR techniques were applied on the diamagnetic yttrium analogue and established that these species retained their solid-state structure in solution with hydrodynamic radii of 6.5 Å. Full 1H, 13C, 15N, 89Y, Δ1Hcoord, Δ13Ccoord, and Δ15Ncoord NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights of these derivatives are provided.

A family of ten novel isostructural LnIII complexes based on the nonsteroidal anti-inflammatory drug diclofenac, with the general formula [Ln2(dicl)6(MeOH)2(H2O)2] [LnIII = Pr (1), Nd (2), Sm(3), Eu (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), Yb (10)], has been prepared. These complexes consist of centrosymmetric dimers in which each metallic centre is coordinated to three diclofenac ligands as well as water and methanol molecules. Alternating current magnetic measurements of complex 6 show a slight SMM behaviour. The evaluation of solid-state photophysical properties reveals that the diclofenac ligand is able to sensitize the luminescence emission of compounds 2, 3, 4, 5, and 6 both in the visible and near-infrared (NIR) regions at 10 K. Measurements of the decay curves show persistent fluorescence, with lifetimes of nearly 1.5 ms, and temperature stable lifetimes in the case of complex 5. Moreover, the NIR emission of compound 2 may open the way to applications in the field of fluoroimmunoassays and in vivo detection, given the bioactive nature of the diclofenac molecule.

Detailed structural, magnetic, and photoluminescence characterization of a family of new compounds based on 5-cyanoisophthalate (CNip) ligand and several transition metal or lanthanide ions, namely, [Cu3(μ3-CNip)2(μ-H2O)2(μ3-OH)2]n (1), {[Co3(μ4-CNip)3(DMF)4]·∼2DMF}n (2), [Cd(μ4-CNip) (DMF)]n (3), {[Ln2(μ4-CNip)(μ3-CNip)2(DMF)4]·∼DMF·H2O}n (4-Ln) (with LnIII = Tb, Dy, and Er), {[Gd6(μ3-CNip)5(μ4-CNip)3(μ-form)2(H2O) (DMF)10]·∼3DMF·3H2O}n (5), {[Zn32(μ4-CNip)12(μ-CNip)12(μ4-O)8(H2O)24]·∼12DMF}n (6) (where DMF = dimethylformamide, form = formate), is reported. The large structural diversity found in the system may be explained mainly in terms of the coordination characteristics that are inherent to the employed metal ions, the coordination versatility of the dicarboxylic ligand and the synthetic conditions. Interestingly, some crystal structures (three-dimensional (3D) frameworks of 4-Ln and 5 and 3D network of 6) exhibit open architectures containing large solvent-occupied void systems, among which 5 reveals permanent porosity as confirmed by N2 adsorption measurements at 77 K. Magnetic direct current (dc) susceptibility data on compounds 1, 2, and 5 were measured. Moreover, compounds 2, 4-Dy, 4-Er, and 5 show slow magnetic relaxation, from which it is worth highlighting the effective energy barrier of 44 K at zero dc field for the dysprosium counterpart. Compound 5 also deserves to be mentioned given the few 3D Gd-organic frameworks reported examples. Photophysical properties were also accomplished at different temperatures, confirming both the fluorescent emission of 5-cyanoisophthalate ligands when coordinated to cadmium ions in 3 and their capacity to sensitize the long-lived fluorescence of the selected lanthanide ions in 4-Ln. Broken symmetry and time-dependent density functional theory computational calculations support the experimental luminescence and magnetic properties.

We have synthesized a new family of metal–organic-frameworks (MOFs) based on a 9,10-anthracenedicarboxylate linker. We report the formation of lanthanide-based MOFs using soft solvothermal routes with dimethylformamide as a solvent. These materials display intense photoluminescence properties in the solid state at room temperature. What is more interesting is, some of them exhibit slow relaxation of magnetization with activation barriers of 22.9, 15.4, 52.7, 13.0 and 16.2 K for Nd3+, Gd3+, Dy3+, Er3+ and Yb3+, respectively. To the best of our knowledge, Nd3+ and Yb3+ materials are the first examples of 3D- and 2D-MOFs, respectively, that show slow relaxation of magnetization.

Four new compounds based on zinc(II) or cadmium(II) metal ions and elongated dicarboxylate and bipyridine ligands, namely, {[Cd3(μ4-bpdc)3(H2O)2]·DMF}n (1), {[Zn3(μ4-bpdc)3(μ-bpdb)]·5DMF}n (2), {[Zn2(μ4-bpdc)2(μ-bpdb)]·7DMF}n (3), and {[Zn4(μ4-bpdc)3(DMF)(μ4-O)(H2O)]·7DMF·3H2O}n (4), (where bpdc = biphenyl-4,4′-dicarboxylate, bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, DMF = dimethylformamide) have been synthesised under solvothermal conditions and structurally characterised by single crystal X-ray diffraction. The crystal structures range from 2D (in 1) to 3D (2, 3, and 4) systems according to the coordination mode acquired by the bpdc ligand and the presence of an ancillary linker. Compound 1 consists of stacked Cd-bpdc neutral layers containing isolated small voids. The coordination of the bpdb ligand (2 and 3) or the formation of a tetrahedral Zn4O cluster (in 4) generates highly open 3D architectures that share the structural feature of being doubly interpenetrated. A careful computational analysis on the crystal structures permits unravelling their void systems. Moreover, characterising the photoluminescence emission of the compounds at variable excitation wavelengths provides an opportunity to couple the luminescence response with their porosity, which could signify the potential utility of these materials as photofluorescent sensors for small adsorbates.

Three novel metal–organic-frameworks (MOFs) based on dysprosium as the metal and dicarboxylic ligands have been solvothermally synthesized with the aim of studying and modulating their magnetic properties according to the variation of the distances between metal centers. These materials display intense photoluminescence properties in the solid state at room temperature. In addition, a very interesting property of compound 1 is that it exhibits slow relaxation of magnetization with an activation energy barrier of 32 K. Magneto-structural correlations have been analyzed.

We have synthesized a novel zinc metal–organic framework (MOF) under mild hydrothermal routes using 5-aminotetrazole and methyl-2-amino-4-isonicotinate anionic ligands. The MOF exhibits a three-dimensional structure with intense blue-greenish photoluminescence emission at room temperature in the solid state. The luminescence, porosity, and adsorption capacity for CO2 and H2 of the Zn-based MOF have been fully determined using a combination of computational methods and experimental techniques. The synthesized Zn-based compound in this study exhibited a remarkable in vivo anti-diabetic activity and low in vitro cell toxicity.

We have designed and synthesized two novel vanadium coordination compounds using 1H-benzimidazole-2-carboxylic acid and 5-aminopyridine-2-carboxylic acid. These two materials have a mononuclear structure with crystallization water molecules in the network. Both compounds exhibit intense photoluminescence emission at room temperature in the solid state and show in vivo antidiabetic activity together with low in vitro cell toxicities. Luminescence theoretical studies have been performed.

A series of zinc(II) or cadmium(II)-based compounds with elongated dicarboxylate and bipyridine ligands, namely {dma[Cd(μ-azdc)(μ-ac)]·xDMF}n (1), {[Cd2(μ4-azdc)(μ-azdc)(DMSO)4]·DMSO}n (2), [Cd3(μ4-azdc)3(DMF)2]n (3), {[Zn2(μ3-azdc)2(μ-pbptz)]·xDMF}n (4), and {[Zn3(μ4-azdc)3(μ-pbptz)2]·xDMF·yH2O}n (5) (where dma = dimethylammonium, azdc = azobenzene-4,4′-dicarboxylate, ac = acetate, DMF = dimethylformamide, DMSO = dimethylsulfoxide, pbptz = 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine), have been synthesized under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction. Crystal structures range from 2D to 3D systems according to the presence of the pbptz co-ligand, which aids the layers established by azdc ligands to increase their dimensionality. The structural diversity found in each system is the result of three factors that govern the assembling process by modulating the coordination mode of the azdc ligands: the employed solvent, counterion and metal:ligand stoichiometry. A common structural feature of these compounds is the highly open architectures achieved due to the length of the employed ligands, which favours the resulting frameworks to be interpenetrated by different degrees depending on the network topology. A careful computational analysis of the void systems of the compounds permits establishing a relationship of this phenomenon with the pore size. The photoluminescence properties of all compounds have been also investigated.

Five multidimensional cadmium metal–organic frameworks based on the luminescent 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene linker and flexible dicarboxylate ligands have been synthesized by conventional routes. These MOFs show fascinating structures and display, in the solid state and at room temperature, intense and hypsochromic photoluminescence properties when packed as a 3D network and bathochromic photoluminescence properties when arranged as 2D networks, as compared to the emission properties of the free luminescent 4-bpdb ligand. DFT calculations have revealed the establishment of destabilizing π–π stacking interactions between pyridyl rings of neighbouring 4-bpdb aromatic linkers on the 3D networks synthesized, responsible for the unexpected hypsochromic emission. The absence of π–π stacking interactions in the 2D MOFs yields the expected bathochromic photoluminescence arising from metal coordination with the aromatic ligand.

The ligand 4,4′-(1,2,4,5-tetrazine-3,6-diyl)dibenzoic acid has been designed and explored with the aim of using it as a linker to construct three-dimensional metal–organic frameworks (MOFs). We have been successful in the formation of a potassium 3D-MOF using this novel linker. This compound has a three-dimensional structure, wherein the layers formed by potassium ions and carboxylate groups are separated by this organic ligand. Luminescence and cytotoxicity studies have been performed. We used molecular simulations to predict the porous properties of an isoreticular compared to IRMOF-16 based on this linker due to the similarity of the newly designed ligand with p-terphenyl-4,4′′-dicarboxylate present in IRMOF-16.

•New metal–organic frameworks based on 5-(4-pyridyl)tetrazole.•Hydrothermal syntheses reveal new possibilities to rational formation on MOFs.•Cadmium MOFs exhibit blue-green long lifetime photoluminescence.•Theoretical studies about pore size distribution and experimental gas adsorption.Three new metal–organic frameworks based on 5-(4-pyridyl)tetrazole have been synthesized by hydrothermal routes mixing this linker with cadmium(II) chloride in the presence of secondary ligands such as squaric acid, 4-carboxypyridine and terephthalic acid in water. Hydrothermal syntheses reveal new possibilities to rational formation on MOFs by mixtures of different linkers using the appropriate stoichiometry. These polymers exhibit blue-green photoluminescence emission at room temperature in the solid state with long lifetime decays. Theoretical studies about pore size distribution and experimental gas adsorption studies have also been included.Three new metal–organic frameworks based on 5-(4-pyridyl)tetrazole have been synthesized by hydrothermal routes mixing this linker with cadmium(II) chloride in the presence of secondary ligands such as squaric acid, 4-carboxypyridine and terephthalic acid in water. These polymers exhibit blue-green long lifetime photoluminescence emission at room temperature in the solid state. Theoretical studies about pore size distribution and experimental gas adsorption studies have also been included.

•Synthesis of six new cadmium(II) coordination compounds with pyrazole, tetrazole, and pyrimidine derivatives.•All complexes have been characterized by X-ray crystallography.•Some compounds exhibit an open crystal structure with large voids.•Topological analysis have been conducted and a new topology has been described.Six new compounds with functionalized pyrazole, tetrazole, and pyrimidine ligands, namely [Cd(μ-4-Hampz)(μ-Cl)2]n(1), [Cd(μ3-pzdc)(μ-H2O)(H2O)]n(2), [Cd(μ-5-amtz)2(eda)]n(3), {[Cd9(μ4-5-amtz)8(μ-Cl)10(H2O)2]⋅xH2O}n(4), {[Cd2(μ-dm2-pmc)2Cl2(H2O)2]⋅H2O}n(5), and [Cd2(μ-Br2-pmc)(μ-Cl)3(H2O)2]n(6) (where 4-Hampz = 4-aminopyrazole, pzdc = 3,5-pyrazoledicarboxylate, 5-amtz = 5-aminotetrazolate, eda = ethylenediamine, dm2-pmc = 4,6-dimethoxy-2-pyrimidinecarboxylate, Br2-pmc = 5-bromopyrimidine-2-carboxylate) have been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction. Compounds 1 and 2 share the structural feature of being constructed from dinuclear building units that are further connected through the pyrazole based ligands, rendering a compact and a potentially open 3D frameworks, respectively. On the other hand, 5-amtz ligand exhibits two different coordination modes in compounds 3 and 4 as a result of the presence or absence of an additional blocking ligand. In this way, the μ-κ4N,N′,N″,  N‴N‴ mode in 4 affords robust clusters that are joined in a topologically novel 3D open architecture containing two types of channels, whereas a simple bidentate bridging mode is limited for 5-amtz in 3 due to the presence of the chelating eda ligand. 1D and 3D structures are obtained with pyrimidine ligands in compounds 5 and 6 according to the steric hindrance of the substituents.

Bidimensional novel cadmium metal-organic frameworks (MOFs) based on the 1,3-bis(4-pyridyl)propane linker and flexible dicarboxylate ligands derived from glutarate (2-methylglutarate, 2-dimethylglutarate and 3-methylglutarate) have been synthesized by conventional routes. These MOFs show fascinating structural features and they display long lifetime photoluminescence emission in the solid state, at room temperature.We report the synthesis of three novel Cd bidimensional polymers based on the flexible ligand 1,3-bis(4-pyridil)propane and different glutarate anions. All three structures were obtained by slow diffusion of solutions of the starting materials. All of them show long-lived luminescence.

We report on the synthesis of two new Zn metal–organic frameworks with 1,3-tetrazolatephenyl-acetic and 1,4-tetrazolatephenyl-acetic spacers obtained in situ by hydrothermal routes. These three-dimensional structures exhibit intense blue-green long lifetime photoluminescence emission at room temperature in the solid state. To the best of our knowledge, this is the first time that coordination compounds have been synthesized with these ligands.

A novel Zn mononuclear complex with 3-carboxy-pyrazole ligand has been prepared using conventional routes and characterized by X-ray diffraction. The structure consists of discrete neutral [Zn(C6H3N2O2)2(H2O)2] molecules held together by hydrogen interactions. This compound exhibits a potential in vivo antidiabetic activity and the in vitro toxicity can be considered negligible.A novel Zn mononuclear complex with 3-carboxy-pyrazole ligand has been prepared using conventional routes and characterized by X-Ray diffraction. The structure consists of discrete neutral [Zn(C4H3N2O2)2(H2O)2] molecules held together by hydrogen interactions. This compound exhibits a potential in vivo antidiabetic activity. Moreover, we have evaluated the in vitro toxicity concluding that it can be considered negligible.

The synthesis of a new MOF with Cu2 paddle-wheels connected to glutarate and 1,3-bis(4-pyridyl)propane linkers has been explored. Experimental gas adsorption measurements reveal that the MOF is essentially non-porous to methane whereas it presents a type III isotherm upon CO2 adsorption, leading to high capacity and outstanding CO2 selectivity.

We report the synthesis of a novel ligand, 3,3′-(1,2,4,5-tetrazine-3,6-diyl)dibenzoic acid (1). In this fragment, we have introduced two carboxylate groups with the aim of using this ligand as a linker to construct three-dimensional metal–organic frameworks (MOFs). We have been successful in the formation of zinc (2) and lanthanum (3) MOFs. The zinc compound is a two-dimensional structure, while the lanthanum material is a three-dimensional MOF with interesting channels. We include the luminescence and adsorption studies of these materials. Moreover, we have evaluated the in vitro toxicity of this novel ligand, concluding that it can be considered negligible.

Three new metal–organic frameworks based on 5-(1H-tetrazol-5-yl)isophthalic acid complexes {[Cd4(TZI)2(OH)2(H2O)4](H2O)6}n (1), {[Zn2(TZI)(OH)(H2O)2](H2O)}n (2) and {[Co8(TZI)3(OH)5((N3)2(H2O)8](H2O)8}n (3) have been synthesized in situ by hydrothermal reactions of the 5-cyano-1,3-benzenedicarboxylic acid ligand with cadmium, zinc and cobalt metallic(II) salts in the presence of sodium azide in water. Compounds 1 and 2 display intense photoluminescence properties in the solid state at room temperature, while 3 exhibits an antiferromagnetic interaction between cobalt(II) ions with a J value of −3.8 cm−1. The in situ hydrothermal syntheses reveal new possibilities for the formation of new MOFs to construct new materials with fascinating structures and potential applications.

The hydrothermal reaction of La(NO3)3 with 2-pyrimidinecarbonitrile in water yields a 3D metal-organic coordination framework [La2(ox)3(H2ox)(H2O)2](H2O)8 (1) (ox = oxalate). This compound has channels with hosted water molecules inside and shows an intense photoluminescence emission at room temperature in the solid state. Due to the great channels that this compound possesses we have analyzed the experimental and simulated adsorption properties. This is one of the few examples of three-dimensional lanthanum polymers based only on oxalate ligand.The hydrothermal reaction of La(NO3)3 with 2-pyrimidinecarbonitrile in water yields a 3D metal-organic coordination framework [La2(ox)3(H2ox)(H2O)2](H2O)8 (ox = oxalate). This compound has channels with hosted water molecules inside and shows an intense photoluminescence emission at room temperature in the solid state. Due to the great channels that this compound possesses we have analyzed the experimental and simulated adsorption properties. This is one of the few examples of three-dimensional lanthanum polymers based only on oxalate ligand.

Two new metal–organic frameworks based on 5-bromonicotinic acid complexes [Cd(5-BrNic)2]n (1) and [Co(5-BrNic)2(H2O)]n (2) have been synthesized by hydrothermal reactions of this ligand with cadmium and cobalt metallic(II) salts in the presence of water. Compound 1 displays intense photoluminescence properties in the solid state at room temperature, while 2 exhibits an antiferromagnetic interaction between Co(II) ions with a J value of −4.1 cm−1. Experimental studies, backed up by Monte Carlo simulations about adsorption, pore size distribution and accessible surface area reveal the capability of 2 for H2 purification applications.

Four new multidimensional copper(II) complexes [Cu(BTA)(2,2′-bipy)H2O] (1), [Cu(BTA)(1,10′-phen)] (2), [Cu2(BTA)2(H2O)4] (3) and [Cu(BTA)(en)]n (4) have been synthesized by conventional and hydrothermal reactions of the bis(5-tetrazolyl)amine (H2BTA) with copper(II) salts in the presence of different ancillary ligands. X-ray diffraction studies on these compounds show 1 and 2 are mononuclear entities, in which the BTA ligand acts in a chelate coordination mode and the copper atoms exhibit a coordination environment intermediate between trigonal-bipyramidal and square-pyramidal for 1 and between square-planar and tetrahedral for 2. Complex 3 consists of centrosymmetric dinuclear molecules with the ligand acting in a μ2-1,1′:2 chelate/bridging tridentate coordination mode and 4 is a linear zigzag neutral chain bearing a BTA bridging ligand in a μ2-1,1′:3 chelate/bridging tridentate coordination mode. Complexes 3 and 4 exhibit antiferromagnetic and very weak ferromagnetic interactions, respectively. DFT calculations have been performed in order to explain their respective magnetic behaviors.Graphical abstractFour new multidimensional copper(II) complexes have been synthesized by conventional and hydrothermal reactions of the bis(5-tetrazolyl)amine (H2BTA) with copper(II) salts in the presence of different ancillary ligands. X-ray diffraction studies on these compounds show a great structural diversity highlighting a centrosymmetric dinuclear molecule and a linear zigzag neutral chain. These complexes exhibit antiferromagnetic and very weak ferromagnetic interactions, respectively. DFT calculations have been performed in order to explain their respective magnetic behaviors.Highlights► Four novel copper complexes with bis(5-tetrazolyl)amine (H2BTA). ► Few copper(II) complexes bearing this ligand have been reported so far. ► Antiferromagnetic and ferromagnetic interactions are studied. ► The sign and value of magnetic couplings are analyzed by DFT calculations.

Conventional reactions of the versatile multidentate ligand 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO) with metallic(II) salts lead to three novel multidimensional complexes [Cu(HmtpO)2(H2O)3](ClO4)2·H2O (1), {[Cu(HmtpO)2(H2O)2](ClO4)2·2HmtpO}n (2) and {[Co(HmtpO)(H2O)3](ClO4)2·2H2O}n (3). In each compound, the triazolopyrimidine ligand shows a different and unusual coordination mode, giving rise to structures with diverse topologies and dimensionality. Compound 1 is a monomeric complex, in which HmtpO shows both N3-monodentate and N1,O71-bidentate modes. 2 is a bidimensional framework with the ligand showing a N3,O71 bidentate-bridging mode. The structure of 3 consists of 1D chains, in which HmtpO displays a N1,N3,O71-tridentate-bridging mode. It should be noted that these coordination modes of the HmtpO ligand are unique in the case of compounds 2 and 3. On the other hand, the magnetic properties of the polynuclear complexes 2 and 3 have been studied showing weak ferromagnetic and antiferromagnetic behaviour, respectively.

The compound [La(pmtz)(TzC)(H2O)3](H2O) (pmtz = 5-(pyrimidyl)-tetrazolato, TzC = 5-carboxylato-tetrazolato) has been prepared under hydrothermal conditions and exhibits a 3D diamondoid network. This three-dimensional metal–organic framework has channels with hosted water molecules inside and shows an intense blue-greenish long lifetime photoluminescence emission at room temperature in the solid state with two lifetime decay values of 0.26 and 27 ms.

Eight new multidimensional metal(II) complexes [Zn(tp)2(NCS)2] (1), [Ni(tp)2(H2O)2(µ-tp)2Ni(NCS)4]n (2), [Co(tp)2(H2O)2(µ-tp)2Co(NCS)4]n (3), [Cd(tp)2(NCS)2]n (4), [Mn(tp)2(NCS)2(H2O)2] (5), [Zn(tp)2(NCO)2] (6), [Cd(tp)(NCO)2]n (7) and [Cd(tp)(N3)2]n (8) have been synthesized by conventional reactions of the 1,2,4-triazolo[1,5-a]pyrimidine with metallic(II) salts in the presence of thiocyanate, cyanate and azide as auxiliary ligands. X-Ray diffraction studies on these compounds show that species 1, 5 and 6 are mononuclear units in which zinc and manganese have tetrahedral and octahedral coordination geometry, respectively. Complexes 2 and 3 are isostructural and consist of neutral chains with triazolopyrimidine bridging ligands through N1, N3 nitrogen atoms. Compound 4 exhibits a 2D rectangular-grid-like structure and complexes 7 and 8 are cyanate-bridged chains formed by defective cubanes. Magnetic and luminescent properties of these materials have also been studied.

The [Re2(µ-trz-κN1:κN2)2(µ-OH)(CO)6]− (trz = 1,2,4-triazolate) organometallic anion reacts with Ag+ to afford a 2D organometallic/coordination network, [Ag{Re2(µ3-trz-κN1:κN2:κN4)2(µ3-OH)(CO)6}]n·4nCH3OH, which shows dynamic structural changes triggered by solid–liquid guest exchange processes.

The title compounds, which have been prepared from M(II) salts (M = Co and Fe) and 5-(pyrimidyl)tetrazole under hydrothermal conditions, are isomorphous and exhibit a 2D square-grid-like structure; the cobalt complex is a spin-canted antiferromagnet with Tc = 15 K.

The synthesis of a new MOF with Cu2 paddle-wheels connected to glutarate and 1,3-bis(4-pyridyl)propane linkers has been explored. Experimental gas adsorption measurements reveal that the MOF is essentially non-porous to methane whereas it presents a type III isotherm upon CO2 adsorption, leading to high capacity and outstanding CO2 selectivity.

We have synthesized a new family of metal–organic-frameworks (MOFs) based on a 9,10-anthracenedicarboxylate linker. We report the formation of lanthanide-based MOFs using soft solvothermal routes with dimethylformamide as a solvent. These materials display intense photoluminescence properties in the solid state at room temperature. What is more interesting is, some of them exhibit slow relaxation of magnetization with activation barriers of 22.9, 15.4, 52.7, 13.0 and 16.2 K for Nd3+, Gd3+, Dy3+, Er3+ and Yb3+, respectively. To the best of our knowledge, Nd3+ and Yb3+ materials are the first examples of 3D- and 2D-MOFs, respectively, that show slow relaxation of magnetization.

The [Re2(µ-trz-κN1:κN2)2(µ-OH)(CO)6]− (trz = 1,2,4-triazolate) organometallic anion reacts with Ag+ to afford a 2D organometallic/coordination network, [Ag{Re2(µ3-trz-κN1:κN2:κN4)2(µ3-OH)(CO)6}]n·4nCH3OH, which shows dynamic structural changes triggered by solid–liquid guest exchange processes.

Conventional reactions of the versatile multidentate ligand 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO) with metallic(II) salts lead to three novel multidimensional complexes [Cu(HmtpO)2(H2O)3](ClO4)2·H2O (1), {[Cu(HmtpO)2(H2O)2](ClO4)2·2HmtpO}n (2) and {[Co(HmtpO)(H2O)3](ClO4)2·2H2O}n (3). In each compound, the triazolopyrimidine ligand shows a different and unusual coordination mode, giving rise to structures with diverse topologies and dimensionality. Compound 1 is a monomeric complex, in which HmtpO shows both N3-monodentate and N1,O71-bidentate modes. 2 is a bidimensional framework with the ligand showing a N3,O71 bidentate-bridging mode. The structure of 3 consists of 1D chains, in which HmtpO displays a N1,N3,O71-tridentate-bridging mode. It should be noted that these coordination modes of the HmtpO ligand are unique in the case of compounds 2 and 3. On the other hand, the magnetic properties of the polynuclear complexes 2 and 3 have been studied showing weak ferromagnetic and antiferromagnetic behaviour, respectively.