Co-reporter:Montse Bazaga-García, Maria Papadaki, Rosario M. P. Colodrero, Pascual Olivera-Pastor, Enrique R. Losilla, Belén Nieto-Ortega, Miguel Ángel G. Aranda, Duane Choquesillo-Lazarte, Aurelio Cabeza, and Konstantinos D. Demadis
Chemistry of Materials 2015 Volume 27(Issue 2) pp:424
Publication Date(Web):December 20, 2014
DOI:10.1021/cm502716e
The structural and functional chemistry of a family of alkali-metal ions with racemic R,S-hydroxyphosphonoacetate (M-HPAA; M = Li, Na, K, Cs) are reported. Crystal structures were determined by X-ray data (Li+, powder diffraction following an ab initio methodology; Na+, K+, Cs+, single crystal). A gradual increase in dimensionality directly proportional to the alkali ionic radius was observed. [Li3(OOCCH(OH)PO3)(H2O)4]·H2O (Li-HPAA) shows a 1D framework built up by Li-ligand “slabs” with Li+ in three different coordination environments (4-, 5-, and 6-coordinated). Na-HPAA, Na2(OOCCH(OH)PO3H)(H2O)4, exhibits a pillared layered “house of cards” structure, while K-HPAA, K2(OOCCH(OH)PO3H)(H2O)2, and Cs-HPAA, Cs(HOOCCH(OH)PO3H), typically present intricate 3D frameworks. Strong hydrogen-bonded networks are created even if no water is present, as is the case in Cs-HPAA. As a result, all compounds show proton conductivity in the range 3.5 × 10–5 S cm–1 (Cs-HPAA) to 5.6 × 10–3 S cm–1 (Na-HPAA) at 98% RH and T = 24 °C. Differences in proton conduction mechanisms, Grothuss (Na+ and Cs+) or vehicular (Li+ and K+), are attributed to the different roles played by water molecules and/or proton transfer pathways between phosphonate and carboxylate groups of the ligand HPAA. Upon slow crystallization, partial enrichment in the S enantiomer of the ligand is observed for Na-HPAA, while the Cs-HPAA is a chiral compound containing only the S enantiomer.
Co-reporter:Melina Preari ; Katrin Spinde ; Joëlle Lazic ; Eike Brunner
Journal of the American Chemical Society 2014 Volume 136(Issue 11) pp:4236-4244
Publication Date(Web):February 24, 2014
DOI:10.1021/ja411822s
Mono- and disilicic acids were stabilized by uncharged polyethylene glycols (PEGs) in silica-supersaturated solutions (the starting solution contained 500 ppm/8.3 mM sodium orthosilicate, Na2SiO3·5H2O, expressed as SiO2) at pH = 7, most likely by hydrogen bonding between the silanol groups and −CH2–CH2–O–ether moieties. The stabilization was monitored by measuring molybdate-reactive silica and also by a combination of liquid- and solid-state 29Si NMR spectroscopy. It depends on PEG concentration (20–100 ppm) and molecular weight (1550–20 000 Da). Two narrow 29Si NMR signals characteristic for monosilicic acid (Q0) and disilicic acid (Q1) can be observed in 29Si NMR spectra of solutions containing PEG 10000 with intensities distinctly higher than the control, that is, in the absence of PEG. Silica-containing precipitates are observed in the presence of PEG, in contrast to the gel formed in the absence of PEG. These precipitates exhibit similar degrees of silica polycondensation as found in the gel as can be seen from the 29Si MAS NMR spectra. However, the 2D HETCOR spectra show different 1H NMR signal shifts: The signal due to H-bonded SiOH/H2O, which is found at 6 ppm in the control, is shifted to ∼7 ppm in the PEG-containing precipitate. This indicates the formation of slightly stronger H-bonds than in the control sample, most likely between PEG and the silica species. The presence of PEG in these precipitates is unequivocally proven by 13C CP MAS NMR spectroscopy. The 13C signal of PEG significantly shifts and is much narrower in the precipitates as compared to the pristine PEG, indicating that PEG is embedded into the silica or at least bound to its surface (or both), and not phase separated. FT-IR spectra corroborate the above arguments. The H-bonding between silanol and ethereal O perturbs the band positions attributed to vibrations involving the O atom. This work may invoke an alternative way to envision silica species stabilization (prior to biosilica formation) in diatoms by investigating possible scenarios of uncharged biomacromolecules playing a role in biosilica synthesis.
Co-reporter:Montse Bazaga-García ; Rosario M. P. Colodrero ; Maria Papadaki ; Piotr Garczarek ; Jerzy Zoń ; Pascual Olivera-Pastor ; Enrique R. Losilla ; Laura León-Reina ; Miguel A. G. Aranda ; Duane Choquesillo-Lazarte ; Konstantinos D. Demadis ;Aurelio Cabeza
Journal of the American Chemical Society 2014 Volume 136(Issue 15) pp:5731-5739
Publication Date(Web):March 18, 2014
DOI:10.1021/ja500356z
We report the synthesis, structural characterization, and functionality (framework interconversions together with proton conductivity) of an open-framework hybrid that combines Ca2+ ions and the rigid polyfunctional ligand 5-(dihydroxyphosphoryl)isophthalic acid (PiPhtA). Ca2[(HO3PC6H3COOH)2]2[(HO3PC6H3(COO)2H)(H2O)2]·5H2O (Ca-PiPhtA-I) is obtained by slow crystallization at ambient conditions from acidic (pH ≈ 3) aqueous solutions. It possesses a high water content (both Ca coordinated and in the lattice), and importantly, it exhibits water-filled 1D channels. At 75 °C, Ca-PiPhtA-I is partially dehydrated and exhibits a crystalline diffraction pattern that can be indexed in a monoclinic cell with parameters close to the pristine phase. Rietveld refinement was carried out for the sample heated at 75 °C, Ca-PiPhtA-II, using synchrotron powder X-ray diffraction data, which revealed the molecular formula Ca2[(HO3PC6H3COOH)2]2[(HO3PC6H3(COO)2H)(H2O)2]. All connectivity modes of the “parent” Ca-PiPhtA-I framework are retained in Ca-PiPhtA-II. Upon Ca-PiPhtA-I exposure to ammonia vapors (28% aqueous NH3) a new derivative is obtained (Ca-PiPhtA-NH3) containing 7 NH3 and 16 H2O molecules according to elemental and thermal analyses. Ca-PiPhtA-NH3 exhibits a complex X-ray diffraction pattern with peaks at 15.3 and 13.0 Å that suggest partial breaking and transformation of the parent pillared structure. Although detailed structural identification of Ca-PiPhtA-NH3 was not possible, due in part to nonequilibrium adsorption conditions and the lack of crystallinity, FT-IR spectra and DTA-TG analysis indicate profound structural changes compared to the pristine Ca-PiPhtA-I. At 98% RH and T = 24 °C, proton conductivity, σ, for Ca-PiPhtA-I is 5.7 × 10–4 S·cm–1. It increases to 1.3 × 10–3 S·cm–1 upon activation by preheating the sample at 40 °C for 2 h followed by water equilibration at room temperature under controlled conditions. Ca-PiPhtA-NH3 exhibits the highest proton conductivity, 6.6 × 10–3 S·cm–1, measured at 98% RH and T = 24 °C. Activation energies (Ea) for proton transfer in the above-mentioned frameworks range between 0.23 and 0.4 eV, typical of a Grothuss mechanism of proton conduction. These results underline the importance of internal H-bonding networks that, in turn, determine conductivity properties of hybrid materials. It is highlighted that new proton transfer pathways may be created by means of cavity “derivatization” with selected guest molecules resulting in improved proton conductivity.
Co-reporter:Konstantinos D. Demadis, Eirini Armakola, Konstantinos E. Papathanasiou, Gellert Mezei, and Alexander M. Kirillov
Crystal Growth & Design 2014 Volume 14(Issue 10) pp:5234-5243
Publication Date(Web):August 13, 2014
DOI:10.1021/cg501029b
A novel family of four hybrid metal phosphonate coordination polymers is reported that are constructed from divalent metal ions (Ca, Sr, Ba, and Pb) and BPMGLY (bis-phosphonomethylglycine, a phosphonated derivative of glycine). These compounds (and their compositions) are Ca-BPMGLY (CaBPMGLY·H2O), Sr-BPMGLY (SrBPMGLY·H2O), Ba-BPMGLY (Ba3.5(BPMGLY)2·6H2O), and Pb-BPMGLY (PbBPMGLY·H2O). They were obtained by hydrothermal reactions in acidic aqueous solutions (pH range 2.3–5.7) and fully characterized by physicochemical methods and structural analysis. Ca-BPMGLY, Sr-BPMGLY, and Pb-BPMGLY have very similar 3D coordination polymer structures, and the latter two are isostructural. In contrast to the Ca, Sr, and Pb analogs, Ba-BPMGLY possesses a different 2D layered network. These four new compounds, together with our previously reported 2D coordination polymer Mg-BPMGLY (MgBPMGLY·2H2O, Demadis et al. Inorg. Chem. 2012, 51, 7889–7896), were topologically classified revealing (i) the uninodal 3-connected net with the hcb topology in Mg-BPMGLY, (ii) the uninodal 5-connected nets with the bnn and vbj topology in Ca-BPMGLY and Sr-BPMGLY, respectively, and (iii) the very complex topologically unique hexanodal 4,4,6,6,7,8-connected net in Ba-BPMGLY. The vbj topology was also identified in the related Pb-BPMGLY 3D framework. These topological features show that the complexity of BPMGLY-driven 2D and 3D metal–organic networks increases periodically following the Mg < Ca ≤ Sr ≪ Ba trend.
Co-reporter:Rosario M. P. Colodrero, Giasemi K. Angeli, Montse Bazaga-Garcia, Pascual Olivera-Pastor, Didier Villemin, Enrique R. Losilla, Estefania Q. Martos, Gary B. Hix, Miguel A. G. Aranda, Konstantinos D. Demadis, and Aurelio Cabeza
Inorganic Chemistry 2013 Volume 52(Issue 15) pp:8770-8783
Publication Date(Web):July 24, 2013
DOI:10.1021/ic400951s
Two new families of divalent metal hybrid derivatives from the aromatic tetraphosphonic acids 1,4- and 1,3-bis(aminomethyl)benzene-N,N′-bis(methylenephosphonic acid), (H2O3PCH2)2–N–CH2C6H4CH2–N(CH2PO3H2)2 (designated herein as p-H8L and m-H8L) have been synthesized by crystallization at room temperature and hydrothermal conditions. The crystal structures of M[(HO3PCH2)2N(H)CH2C6H4CH2N(H)(CH2PO3H)2(H2O)2]·2H2O (M = Mg, Co, and Zn), M–(p-H6L), and M[(HO3PCH2)2N(H)CH2C6H4CH2N(H)(CH2PO3H)2]·nH2O (M = Ca, Mg, Co, and Zn and n = 1–1.5), M–(m-H6L), were solved ab initio by synchrotron powder diffraction data using the direct methods and subsequently refined using the Rietveld method. The crystal structure of the isostructural M–(p-H6L) is constituted by organic–inorganic monodimensional chains where the phosphonate moiety acts as a bidentate chelating ligand bridging two metal octahedra. M–(m-H6L) compounds exhibit a 3D pillared open-framework with small 1D channels filled with water molecules. These channels are formed by the pillaring action of the organic ligand connecting adjacent layers through the phosphonate oxygens. Thermogravimetric and X-ray thermodiffraction analyses of M–(p-H6L) showed that the integrity of their crystalline structures is maintained up to 470 K, without significant reduction of water content, while thermal decomposition takes place above 580 K. The utility of M–(p-H6L) (M = Mg and Zn) hybrid materials in corrosion protection was investigated in acidic aqueous solutions. In addition, the impedance data indicate both families of compounds display similar proton conductivities (σ ∼ 9.4 × 10–5 S·cm–1, at 98% RH and 297 K), although different proton transfer mechanisms are involved.
Co-reporter:Konstantinos D. Demadis, Aggeliki Panera, Zafeiria Anagnostou, Dimitris Varouhas, Alexander M. Kirillov, and Ivana Císařová
Crystal Growth & Design 2013 Volume 13(Issue 10) pp:4480-4489
Publication Date(Web):August 13, 2013
DOI:10.1021/cg4009625
The outcome of a synthesis involving a metal ion and a (poly)phosphonic acid depends on a plethora of variables such as solution pH, reactant molar ratios, nature of the metal ion, number of phosphonate groups, and other “functional” moieties present on the ligand backbone. Products are usually coordination polymers of diverse dimensionality. Here we report that the use of a chelating auxiliary ligand (2,2′-bpy) can “disrupt” the polymeric architecture of the copper phosphonate, causing the isolation of a series of molecular complexes (mononuclear or binuclear) that incorporate both the phosphonate and the 2,2′-bpy ligands. Synthetic details, crystal structures, and intermolecular interactions (π–π stacking and hydrogen bonding) are discussed. The structures of the obtained Cu complexes are extended into 2D or 3D networks via multiple hydrogen bonds involving the molecular units and crystallization water molecules. These H-bonded networks have been classified from the topological viewpoint, revealing diverse topologies that also include their undocumented types.
Co-reporter:Rosario M. P. Colodrero, Konstantinos E. Papathanasiou, Nikoleta Stavgianoudaki, Pascual Olivera-Pastor, Enrique R. Losilla, Miguel A. G. Aranda, Laura León-Reina, Jesús Sanz, Isabel Sobrados, Duane Choquesillo-Lazarte, Juan M. García-Ruiz, Pedro Atienzar, Fernando Rey, Konstantinos D. Demadis, and Aurelio Cabeza
Chemistry of Materials 2012 Volume 24(Issue 19) pp:3780
Publication Date(Web):September 15, 2012
DOI:10.1021/cm302381k
The chemistry of metal phosphonates has been progressing fast with the addition of new materials that possess novel structural features and new properties, occasionally in a cooperative manner. In this paper, we report a new family of functional lanthanide-carboxyphosphonate materials. Specifically, the lanthanide is La, Ce, Pr, Sm, Eu, Gd, Tb, or Dy and the carboxyphosphonate ligand is 2-hydroxyphosphonoacetic acid (H3HPA). All reported LnHPA compounds, Ln3(H0.75O3PCHOHCOO)4·xH2O (x = 15–16), crystallize in the orthorhombic system. Two types of structures were isolated: series I and II polymorphs. For both series, the three-dimensional (3D) open frameworks result from the linkage of similar organo-inorganic layers, in the ac-plane, by central lanthanide cations, which yield trimeric units also found in other metal-HPA hybrids. Large oval-shaped 1D channels are formed by the spatial separation of the layers along the b-axis and filled with lattice water molecules. LnHPA materials undergo remarkable crystalline-to-amorphous-to crystalline transformations upon dehydration and rehydration cycles, as confirmed by thermodiffraction and NMR spectroscopy. The highest proton conductivity was observed for GdHPA (series II), 3.2 × 10–4 S cm–1 at 98% RH and T = 21 °C. The dehydration–rehydration chemistry was also followed by photoluminescence spectroscopy. It was shown that loss and reuptake of water molecules are accompanied by clear changes in the photoluminescence spectra and lifetimes of the Eu analog (series II). Our present results reveal a wide family of well-characterized, multifunctional lanthanide-based phosphonate 3D-structured metal–organic frameworks (MOFs) that show reversible crystalline-to-amorphous-to-crystalline transformations and, at the same time, exhibit high proton conductivity.Keywords: 3D structure; lanthanide; luminescence; MOF; phosphonate; proton conductivity; reversible transformation;
Co-reporter:Johannes Weber, Gisbert Grossmann, Konstantinos D. Demadis, Nikos Daskalakis, Erica Brendler, Martin Mangstl, and Jörn Schmedt auf der Günne
Inorganic Chemistry 2012 Volume 51(Issue 21) pp:11466-11477
Publication Date(Web):October 5, 2012
DOI:10.1021/ic301192y
The 31P chemical shift tensor of the phosphonate group [RC-PO2(OH)]− is investigated with respect to its principal axis values and its orientation in a local coordinate system (LCS) defined from the P atom and the directly coordinated atoms. For this purpose, six crystalline metal aminotris(methylenephosphonates), MAMP·xH2O with M = Zn, Mg, Ca, Sr, Ba, and (2Na) and x = 3, 3, 4.5, 0, 0, and 1.5, respectively, were synthesized and identified by diffraction methods. The crystal structure of water-free BaAMP is described here for the first time. The principal components of the 31P shift tensor were determined from powders by magic-angle-spinning NMR. Peak assignments and orientations of the chemical shift tensors were established by quantum-chemical calculations from first principles using the extended embedded ion method. Structure optimizations of the H-atom positions were necessary to obtain the chemical shift tensors reliably. We show that the 31P tensor orientation can be predicted within certain error limits from a well-chosen LCS, which reflects the pseudosymmetry of the phosphonate environment.
Co-reporter:Rosario M. P. Colodrero, Pascual Olivera-Pastor, Enrique R. Losilla, Miguel A. G. Aranda, Laura Leon-Reina, Maria Papadaki, Alistair C. McKinlay, Russell E. Morris, Konstantinos D. Demadis and Aurelio Cabeza
Dalton Transactions 2012 vol. 41(Issue 14) pp:4045-4051
Publication Date(Web):25 Jan 2012
DOI:10.1039/C2DT11992G
A new flexible ultramicroporous solid, La(H5DTMP)·7H2O (1), has been crystallized at room temperature using the tetraphosphonic acid H8DTMP, hexamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid). Its crystal structure, solved by synchrotron powder X-ray diffraction, is characterised by a 3D pillared open-framework containing 1D channels filled with water. Upon dehydration, a new related crystalline phase, La(H5DTMP) (2) is formed. Partial rehydration of 2 led to La(H5DTMP)·2H2O (3). These new phases contain highly corrugated layers showing different degrees of conformational flexibility of the long organic chain. The combination of the structural study and the gas adsorption characterization (N2 and CO2) suggests an ultramicroporous flexible framework. NO isotherms are indicative of a strong irreversible adsorption of NO within the pores. Impedance data indicates that 1 is a proton-conductor with a conductivity of 8 × 10−3 S cm−1 at 297 K and 98% of relative humidity, and an activation energy of 0.25 eV.
Co-reporter:Nikoleta Stavgianoudaki, Konstantinos E. Papathanasiou, Rosario M. P. Colodrero, Duane Choquesillo-Lazarte, Juan M. Garcia-Ruiz, Aurelio Cabeza, Miguel A. G. Aranda and Konstantinos D. Demadis
CrystEngComm 2012 vol. 14(Issue 17) pp:5385-5389
Publication Date(Web):06 Jun 2012
DOI:10.1039/C2CE25632K
In this paper we report a crystal growth method for metal phosphonate frameworks in alginate gels. It consists of a metal-containing alginate gel, in which a solution of phosphonate ligand is slowly diffused. Crystals of metal phosphonate products are formed inside the gel. We have applied this for a variety of metal ions (alkaline-earth metals, transition metals and lanthanides) and a number of polyphosphonic acid and mixed carboxy/phosphonic acid ligands.
Co-reporter:Konstantinos D. Demadis, Anna Tsistraki, Adriana Popa, Gheorghe Ilia and Aurelia Visa
RSC Advances 2012 vol. 2(Issue 2) pp:631-641
Publication Date(Web):15 Nov 2011
DOI:10.1039/C1RA00448D
Phosphonium-based bolaamphiphiles have been found to stabilise silicic acid beyond its solubility limit (∼150 ppm). Three bolaamphiphiles have been tested having a quaternary phosphonium group on each end, linked by a number of ethylene oxide (EO) units (5, 21, and 91, resulting in PEGP+-200, PEGP+-1000, and PEGP+-4000 dicationic bolaamphiphiles, respectively). Specifically, the ability of PEGP+-200, PEGP+-1000, and PEGP+-4000 to retard silicic acid condensation at circumneutral pH in aqueous supersaturated solutions was explored. The goal was to investigate the effect of P-based cationic molecules, EO chain length (and by inference the P-to-P spatial separation) on silicic acid stabilisation performance. PEGP+-200 showed no stabilisation ability in “long term” tests (i.e. 24, 48, 72 h). For PEGP+-1000, and PEGP+-4000, it was discovered that in “short-term” (0–8 h) and “long term” (> 24 h) studies the inhibitory activity is additive dosage-dependent, demonstrating that there is a clear increase in stabilisation ability upon phosphonium PEG dosage increase. Specifically, soluble silicic acid levels reach 420 ppm and 400 ppm after 24 h in the presence of 150 ppm PEGP+-1000, or PEGP+-4000, respectively. PEG additives (PEG-200, PEG-1000, and PEG-4000) containing no phosphonium cations were also tested. Although PEG-200 and PEG-1000 showed no silicic acid stabilisation effects, PEG-4000, surprisingly, was a strong stabiliser. In fact, the inhibitory efficiencies of PEGP+-4000 and PEG-4000 were virtually identical. These results present strong proof that the polyethylene chain beyond a certain length strongly contributes to silicic acid stabilisation. Lastly, the effects of these boloamphiphiles on silica particle morphology were investigated by SEM. Spherical particles and their aggregates, irregularly shaped particles and porous structures, are obtained depending on the additive.
Co-reporter:Konstantinos D. Demadis, Maria Somara, and Eleftheria Mavredaki
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 7) pp:2952-2962
Publication Date(Web):January 20, 2012
DOI:10.1021/ie202806m
The effect of various fluorine-containing chemical additives on the dissolution of colloidal silica is systematically studied. These silica scale dissolvers are ammonium bifluoride (NH4·HF2), ammonium fluoride (NH4F), sodium tetrafluoroborate (NaBF4), and disodium fluorophosphate (Na2PO3F). The most effective dissolver was NH4·HF2, which was extensively studied at the pH range 2–7. The highest dissolution efficiency was demonstrated in the pH range 2–4. The dissolution capability of Na2PO3F was monitored not by the silicomolybdate method, but on the basis of a weight-loss approach. It showed substantial dissolution ability at pH’s 7 and 9.
Co-reporter:Konstantinos D. Demadis, Antonia Ketsetzi, and Eva-Maria Sarigiannidou
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 26) pp:9032-9040
Publication Date(Web):June 11, 2012
DOI:10.1021/ie3010836
The catalytic role of Mg2+ ions in the polycondensation of silicic acid to form amorphous silica has been investigated in detail. This behavior is pH-dependent. As pH increases (herein, the three pH values 8.0, 9.0, and 9.5 were tested), the catalytic effect of Mg2+ ions becomes more pronounced. Also, this behavior is directly proportional to the concentration of Mg2+. Ethylenediaminetetraacetic acid (EDTA) can inhibit this catalytic effect by strongly chelating the Mg2+ ions. This research can be further expanded to other chelating agents that have an affinity for Mg2+ ions.
Co-reporter:Katrin Spinde, Konstantinos Pachis, Ioanna Antonakaki, Silvia Paasch, Eike Brunner, and Konstantinos D. Demadis
Chemistry of Materials 2011 Volume 23(Issue 21) pp:4676
Publication Date(Web):October 4, 2011
DOI:10.1021/cm201988g
The influence of a number of N-containing macromolecules on the polycondensation of silicic acid to form amorphous silica is studied by the combined use of 29Si NMR spectroscopy and the silicomolybdate test. Polymeric additives include poly(allylamine hydrochloride) (PAH), the poly(aminoamide) dendrimer of generation 1 (PAMAM-1), poly(ethyleneimine) (PEI), and poly(vinylpyrrolidone) (PVP). These studies were performed under biologically relevant conditions (pH 5.4 and 7.0) using aqueous solutions of isotope-labeled sodium [29Si]metasilicate as the precursor compound. It was found at pH 5.4 that all additives accelerate silicic acid polycondensation, except for PVP, which exerts a minor silicic acid stabilizing effect. At pH 7.0, polycondensation is much faster in the presence of PAMAM-1, PEI, and PAH. However, PVP significantly stabilizes mono- and disilicic acid. Silica precipitates were also studied by 29Si NMR spectroscopy. The effect observed for PVP is striking and indicates that the silicic acid polycondensation is slowed, although the oligomers are immobilized by the PVP polymer. In contrast, the charged PAH attracts the oligomeric species and enhances the silicic acid polycondensation.Keywords: 29Si NMR; polyamines; silicic acid polycondensation; silicic acid stabilization; silicomolybdate test;
Co-reporter:Rosario M. P. Colodrero ; Aurelio Cabeza ; Pascual Olivera-Pastor ; Duane Choquesillo-Lazarte ; Juan M. Garcia-Ruiz ; Adele Turner ; Gheorghe Ilia ; Bianca Maranescu ; Konstantinos E. Papathanasiou ; Gary B. Hix ; Konstantinos D. Demadis ;Miguel A. G. Aranda
Inorganic Chemistry 2011 Volume 50(Issue 21) pp:11202-11211
Publication Date(Web):September 27, 2011
DOI:10.1021/ic201760w
A family of M-VP (M = Ni, Co, Cd, Mn, Zn, Fe, Cu, Pb; VP = vinylphosphonate) and M-PVP (M = Co, Cd; PVP = phenylvinylphosphonate) materials have been synthesized by hydrothermal methods and characterized by FT-IR, elemental analysis, and thermogravimetric analysis (TGA). Their structures were determined either by single crystal X-ray crystallography or from laboratory X-ray powder diffraction data. The crystal structure of some M-VP and M-PVP materials is two-dimensional (2D) layered, with the organic groups (vinyl or phenylvinyl) protruding into the interlamellar space. However, the Pb-VP and Cu-VP materials show dramatically different structural features. The porous, three-dimensional (3D) structure of Pb-VP contains the Pb center in a pentagonal pyramid. A Cu-VP variant of the common 2D layered structure shows a very peculiar structure. The structure of the material is 2D with the layers based upon three crystallographically distinct Cu atoms; an octahedrally coordinated Cu2+ atom, a square planar Cu2+ atom and a Cu+ atom. The latter has an unusual co-ordination environment as it is 3-coordinated to two oxygen atoms with the third bond across the double bond of the vinyl group. Metal-coordinated water loss was studied by TGA and thermodiffractometry. The rehydration of the anhydrous phases to give the initial phase takes place rapidly for Cd-PVP but it takes several days for Co-PVP. The M-VP materials exhibit variable dehydration–rehydration behavior, with most of them losing crystallinity during the process.
Co-reporter:Konstantinos D. Demadis, Maria Paspalaki, and Joanna Theodorou
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 9) pp:5873-5876
Publication Date(Web):March 22, 2011
DOI:10.1021/ie102546g
Herein, the controlled release of etidronic acid (hydroxyethylidene-bis(phosphonic) acid), an important drug for osteoporotic conditions, immobilized onto cationic polymeric matrices, such as polyethyleneimine (PEI) or cationic inulin (CATIN) is reported. Several CATIN- and PEI-etidronate composites have been synthesized at various pH regions and characterized. Tablets with starch as the excipient containing the active ingredient (polymer-etidronate composite) were prepared, and the controlled release of etidronate was studied at aqueous solutions of pH 3 (to mimick the pH of the stomach) for 8 h. All studied composites showed a delayed etidronate release in the first 4 h, compared to the “control” (a tablet containing only starch and etidronic acid, without the polymer).
Co-reporter:Konstantinos D. Demadis, Eleftheria Mavredaki, and Maria Somara
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 22) pp:12587-12595
Publication Date(Web):October 12, 2011
DOI:10.1021/ie201703b
The effect of various chemical additives (small molecules and polymers) on the dissolution of two kinds of colloidal silica (Aerosil 200 and laboratory-synthesized, SSD) is systematically studied at pH 10. The silica scale dissolvers tested are 5-carboxybenzotriazole (CBZT), amino-tris(methylene phosphonic acid) (AMP), a phosphino-polycarboxylic acid (PPCA), diethylenetriamine pentacarboxylic acid (DETPA), a proprietary polymer (Genesol 40), poly(acrylic acid) (PAA), ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), phosphonobutane-1,2,4-tricarboxylic acid (PBTC), sodium metaborate, and N-phosphonomethylimino-diacetic acid (PMIDA). Of the polymeric additives only Genesol 40 shows some dissolution activity, dissolving ∼280 ppm silica at 10 000 ppm dosage after 72 h. PBTC and DETPA are the best-performing additives of all those tested. PBTC is effective even at the 2500 ppm dosage, as it solubilizes ∼290 ppm silica after 72 h. Its efficiency is dosage-dependent. DETPA is also an effective silica dissolver. Its behavior is similar to that of PBTC. Its best dosage is 7500 ppm, which yields dissolution of 322 ppm silica (after 24 h), 340 ppm (after 48 h), and 333 ppm (after 72 h). SSD silica is a very recalcitrant deposit showing resistance to dissolution even by the most effective additives, PBTC and DETPA.
Co-reporter:Konstantinos D. Demadis, Eleftheria Mavredaki, and Maria Somara
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 24) pp:13866-13876
Publication Date(Web):November 9, 2011
DOI:10.1021/ie201798e
The effect of various environmentally friendly chemical additives and natural products on the dissolution of amorphous silica (Aerosil 200 and laboratory-synthesized, SSD) is studied. The silica scale dissolvers tested include the following: ascorbic acid (vitamin C, ASC), citric acid (CITR), carboxymethyl inulin (CMI), 3,4-dihydroxybenzoic acid (catechuic acid, DHBA), 3,4,5-trihydroxybenzoic acid (gallic acid, GA), dopamine hydrochloride (DOPA), iminodiacetic acid (IDA), histidine (HIST), phenylalanine (PHALA), and malic acid (MAL). The chemical structures of these chemical additives contain potentially dissolution-active moieties, such as 1,2-dihydroxyethylene (ASC), α-hydroxycarboxylate (MAL and CITR), catecholate (DHBA, GA, and DOPA), α-aminocarboxylate (HIST and PHALA, both aminoacids), and finally carboxy-modified fructofuranose units (CMI). It was found that all studied molecules showed variable dissolution efficiency, with MAL, CMI, HIST, and PHALA being the slowest/least effective dissolvers, and the catechol-containing DHBA, GA, and DOPA being the most effective ones. IDA and CITR have intermediate efficiency.
Co-reporter:Hermann Ehrlich, Konstantinos D. Demadis, Oleg S. Pokrovsky and Petros G. Koutsoukos
Chemical Reviews 2010 Volume 110(Issue 8) pp:4656
Publication Date(Web):May 4, 2010
DOI:10.1021/cr900334y
Co-reporter:Konstantinos D. Demadis, Maria Papadaki and Ivana Císařová
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 7) pp:1814
Publication Date(Web):July 8, 2010
DOI:10.1021/am100382r
In this communication, we report the synthesis and crystallographic characterization of a rare molecular linear trimer composed of Ca2+ and a carboxyphosphonate (hydroxyphosphonoacetate, HPAA), namely Ca3(HPAA)2(H2O)14. The two HPAA3− ligands function as bridges between the three Ca2+ ions. The central Ca2+ center is found in an octahedral environment, whereas the peripheral Ca2+ centers are in an 8-coordinated environment. This Ca3(HPAA)2(H2O)14 trimer was found to be an effective corrosion inhibitor for carbon steel surfaces at pH 7.3. Furthermore, we have proven by a variety of techniques that the identity of the anticorrosion film is the same as the rationally synthesized Ca3(HPAA)2(H2O)14.Keywords: calcium; corrosion inhibitors; phosphonates; thin films
Co-reporter:Rosario M. P. Colodrero ; Pascual Olivera-Pastor ; Aurelio Cabeza ; Maria Papadaki ; Konstantinos D. Demadis ;Miguel A. G. Aranda
Inorganic Chemistry 2010 Volume 49(Issue 2) pp:761-768
Publication Date(Web):December 16, 2009
DOI:10.1021/ic902048b
Reactions of divalent cations (Mg2+, Co2+, Ni2+, and Zn2+) with R,S-hydroxyphosphonoacetic acid (HPAA) in aqueous solutions (pH values ranging 1.0−4.0) yielded a range of crystalline hydrated M-HPAA hybrids. One-dimensional (1D) chain compounds were formed at room temperature whereas reactions conducted under hydrothermal conditions resulted in two-dimensional (2D) layered frameworks or, in some cases, three-dimensional (3D) networks incorporating various alkaline cations. 1D phases with compositions [M{HO3PCH(OH)CO2}(H2O)2]·2H2O (M = Mg, Co, and Zn) were isolated. These compounds were dehydrated in liquid water to yield the corresponding [M{HO3PCH(OH)CO2}(H2O)2] compounds lacking the lattice water between the 1D chains. [M{HO3PCH(OH)CO2}(H2O)2] (M = Mg, Ni, Co, Zn) compounds were formed by crystallization at room temperature (at higher pH values) or also by partial dehydration of 1D compounds with higher hydration degrees. Complete dehydration of these 1D solids at 240−270 °C led to 3D phases, [M{HO3PCH(OH)CO2}]. The 2D layered compound [Mg{HO3PCH(OH)CO2}(H2O)2] was obtained under hydrothermal conditions. For both synthesis methods, addition of alkali metal hydroxides to adjust the pH usually led to mixed phase materials, whereas direct reactions between the metal oxides and the hydroxyphosphonoacetic acid gave single phase materials. On the other hand, adjusting the pH with acetate salts and increasing the ratio M2+/HPAA and/or the A+/M2+ ratio (A = Na, K) resulted in 3D networks, where the alkali cations were incorporated within the frameworks for charge compensation. The crystal structures of eight new M(II)-HPAA hybrids are reported herein and the thermal behavior related to dehydration/rehydration of some compounds are studied in detail.
Co-reporter:Isurika R. Fernando, Nikos Daskalakis, Konstantinos D. Demadis and Gellert Mezei
New Journal of Chemistry 2010 vol. 34(Issue 2) pp:221-235
Publication Date(Web):12 Jan 2010
DOI:10.1039/B9NJ00361D
The present study demonstrates that the pyrazole-4-sulfonate anion (4-SO3-pzH = L−) is a versatile ligand for the preparation of layered, 3-D solid state lattices. The ligand itself can coordinate to metals with both its sulfonate group and aromatic N-atom, as well as participate in hydrogen bonding both as donor and acceptor, and form various extended π–π networks. Five new complexes with Rb+, Cs+, Mg2+, Sr2+ and Cu2+ have been prepared and characterized including single crystal X-ray diffraction: RbL, tetragonal I41/a, a = 9.7332(4) Å, b = 9.7332(4) Å, c = 29.941(1) Å, V = 2836.5(2) Å, Z = 16; CsL, monoclinic P21/c, a = 8.821(1) Å, b = 8.109(1) Å, c = 9.889(2) Å, β = 91.560(3)°, V = 707.1(2) Å, Z = 4; Mg(H2O)6L2, triclinic P, a = 7.0543(7) Å, b = 7.7307(8) Å, c = 8.6389(9) Å, α = 72.572(2)°, β = 74.370(2)°, γ = 76.045(2)°, V = 426.22(8) Å, Z = 1; SrL2, triclinic P, a = 6.027(2) Å, b = 7.243(3) Å, c = 14.186(5) Å, α = 92.491(8)°, β = 101.383(7)°, γ = 97.471(7)°, V = 426.22(8) Å, Z = 2; Cu(H2O)2L2·4H2O, monoclinic P21/c, a = 9.032(1) Å, b = 13.297(1) Å, c = 7.7103(9) Å, β = 109.747(2)°, V = 871.5(2) Å, Z = 2. The varying size and charge of the cations in these five complexes produce unique, alternating inorganic–organic layered materials. We find a correlation between the size and charge of cations and the coordination mode of the ligand as well as hydration of the metal, but no correlation between the nature of the cation and the thickness of the inorganic/organic layers. We conclude that the overall 3-D structure of these layered materials is determined by a subtle balance between the coordination preferences of the metal ion and an intricate lattice of hydrogen bonds and aromatic interactions. Ligand HL and its complexes with Na, K, Rb, Cs, Mg, Ca, Sr and Ba were tested as potential corrosion inhibitors of copper metal surfaces at three different pH values (2, 3, and 4). All the above mentioned compounds show significant corrosion inhibition at pH 4 and 3, while no activity is observed at pH 2. The correlation of inhibition activity with pH of ligand HL and its different metal complexes is discussed.
Co-reporter:Konstantinos D. Demadis, Konstantinos Pachis, Antonia Ketsetzi, Aggeliki Stathoulopoulou
Advances in Colloid and Interface Science 2009 Volume 151(1–2) pp:33-48
Publication Date(Web):30 October 2009
DOI:10.1016/j.cis.2009.07.005
Abstract
This paper focuses on the effects of biological and synthetic polymers on the formation of amorphous silica. A concise review of relevant literature related to biosilicification is presented. The importance of synergies between polyelectrolytes on the inhibition of silicic acid condensation is discussed. A specific example of a zwitterionic polymer phosphonomethylated chitosan (PCH) is further analyzed for its inhibitory activity. Specifically, the ability of PCH to retard silicic acid condensation at circumneutral pH in aqueous supersaturated solutions is explored. It was discovered that in short-term studies (0–8 h) the inhibitory activity is PCH dosage-independent, but for longer condensation times (> 24 h) there is a clear increase in inhibition upon PCH dosage increase. Soluble silicic acid levels reach 300 ppm after 24 h in the presence of 160 ppm PCH. Furthermore, the effects of either purely cationic (polyethyleneimine, PEI) or purely anionic (carboxymethylinulin, CMI) polyelectrolytes on the inhibitory activity of PCH is systematically studied. It was found that the action of inhibitor blends is not cumulative. PCH/PEI blends stabilize the same level of silicic acid as PCH alone in both short-term (8 h) and long-term (72 h) experiments. PCH/CMI combinations on the other hand can only achieve short-term inhibition of silicic acid polymerization, but fail to extend this over the first 8 h. PCH and its combinations with PEI or CMI affect silica particle morphology, studied by SEM. Spherical particles and their aggregates, irregularly shaped particles and porous structures are obtained depending on additive or additive blend. It was demonstrated by FT-IR that PCH is trapped in the colloidal silica matrix.
Co-reporter:Konstantinos D. Demadis, Zafeiria Anagnostou and Hong Zhao
ACS Applied Materials & Interfaces 2009 Volume 1(Issue 1) pp:35
Publication Date(Web):November 24, 2008
DOI:10.1021/am800030h
Dissolution of biologically important sparingly soluble salts, such as calcium carbonate and calcium oxalate, is possible by use of carboxyl- and carboxyl/phosphonate-bearing, anionic additives, citrate, malate, carboxyphosphonate, and butane tetracarboxylate. Calcium-containing dissolution products have been identified, characterized, and independently synthesized. These are polymeric materials composed of calcium and the additive as the ligand. Their full characterization was carried out by single-crystal X-ray crystallography and other techniques.Keywords: calcite dissolution; calcium carbonate; carboxylates; inorganic−organic hybrids; phosphonates
Co-reporter:Konstantinos D. Demadis, Nikoleta Stavgianoudaki, Gisbert Grossmann, Margit Gruner and Joseph L. Schwartz
Inorganic Chemistry 2009 Volume 48(Issue 9) pp:4154-4164
Publication Date(Web):March 26, 2009
DOI:10.1021/ic802400r
The tetra-acid 2-hydroxyethylimino-bis(methylenephosphonic acid) (HEIBPH, 1) and its ring condensation product, the triacid 2-hydroxy-2-oxo-4-phosphonemethyl-1,4,2-oxazaphosphorinane (2), were investigated for determination of protonation constants using 31P, 1H, and 13C NMR spectroscopy in a wide pH range. As for other α-amino-phosphonic acids, the first protonation of 1 is straightforward and occurs at the nitrogen, while for 2 the first protonation occurs simultaneously at the exo phosphonate group, allowing estimation of the microscopic protonation constants. The complexation of Ca2+ with 1 in a 1:1 molar ratio in aqueous solutions and in the presence of a 5-fold excess Na+ is rationalized by the products LCaH2, LCaH, LCaNaH, LCa, and LCa2 (L = 1). Only the phosphonate groups are involved in Ca2+ binding at pH > 3, while the phosphonate, hydroxyl, and amine functionalities coordinate to Ca2+ at pH > 6−7, as soon as the proton at N is lost. Probable conformation states of ions of 1 and 2 are estimated by means of the dependence of vicinal coupling constants 3JHH and 3JPC from dihedral angles.
Co-reporter:Konstantinos D. Demadis ; Eleni Barouda ; Raphael G. Raptis ;Hong Zhao
Inorganic Chemistry 2009 Volume 48(Issue 3) pp:819-821
Publication Date(Web):December 29, 2008
DOI:10.1021/ic802032y
Herein, we describe the preparation and characterization of five new divalent metal tetraphosphonates, M-HDTMP [M = Mg2+, Ca2+, Sr2+, Ba2+, and Cu2+; HDTMP = hexamethylenediaminetetrakis(methylenephosphonate) dianion]. Materials {Sr[(HDTMP)(H2O)6]·2H2O}n (1), {Ba[(HDTMP)(H2O)6]·2H2O}n (2), and {Cu[(HDTMP)(H2O)4]·6H2O}n (3), as well as (en)(HDTMP)·2H2O (en = ethylenediammonium cation) have been structurally characterized. Structures depend on the coordination requirements of the M2+ center and waters of crystallization content. The formation and characterization of effective anticorrosion passive films of M-HDTMP (M = Sr2+ and Ba2+) are also reported.
Co-reporter:Seema Lodhia, Adele Turner, Maria Papadaki, Konstantinos D. Demadis and Gary B. Hix
Crystal Growth & Design 2009 Volume 9(Issue 4) pp:1811-1822
Publication Date(Web):February 6, 2009
DOI:10.1021/cg800992f
The syntheses and structural characterization of 1D, 2D, and 3D materials based on copper phosphonocarboxylate backbones are described. More specifically, the synthesis of materials from diethylphosphonoacetic acid (DEPAA) or the close variant hydroxyphosphonoacetic acid (HPAA) and water-soluble Cu2+ salts has been studied. The initial synthesis involving copper acetate and DEPAA was carried out at 160 °C under hydrothermal conditions and a Cu:P ratio of 1:1 resulted in the formation of a mixture of products with the same composition, Cu1.5(O3PCH2CO2)·H2O. Compound 1, which is blue in color and crystallizes in the triclinic space group P1̅, has a layered structure. Compound 2, which is green in color and crystallizes in the monoclinic space group P21/c, has a three-dimensional structure. Reduction of the reaction temperature to 140 °C results in the exclusive formation of the α-phase (1), while an increase in the reaction temperature to 180 °C yields a pure sample of 2. A Cu:P ratio of 2:3 in a reaction at 180 °C yields a third, related phase, Cu(HO3PCH2CO2)·H2O, 3, which is again triclinic but has a chain-like structure. Finally, reaction of copper chloride and HPAA in a Cu:P ratio of 1:1 at room temperature yields one-dimensional Cu(R,S-HO3PCH(OH)CO2)(H2O)2]·H2O, 4, that incorporates both R and S HPAA stereoisomers. All materials were studied by single crystal X-ray crystallography, X-ray powder diffraction, TGA, FT-IR, and elemental analyses.
Co-reporter:Konstantinos D. Demadis, Eleni Barouda, Nikoleta Stavgianoudaki and Hong Zhao
Crystal Growth & Design 2009 Volume 9(Issue 3) pp:1250-1253
Publication Date(Web):February 9, 2009
DOI:10.1021/cg800748f
Syntheses and structures of alkaline earth metal ions and EDTMP, ethylenediamine-tetrakis(methylenephosphonate), are reported. The isostructural Ca2+ and Sr2+ analogs have 1D topologies, with EDTMP acting as both chelating and bridging ligand. The M-EDTMP compounds act as Fe-oxide removers from corroded surfaces.
Co-reporter:Emel Akyol, Mualla Öner, Eleni Barouda and Konstantinos D. Demadis
Crystal Growth & Design 2009 Volume 9(Issue 12) pp:5145-5154
Publication Date(Web):November 3, 2009
DOI:10.1021/cg9005423
In this study, the effect of phosphonate additives on the crystallization of calcium sulfate dihydrate (CaSO4·2H2O, gypsum) has been investigated in aqueous solutions. Ethylenediamine-tetrakis(methylenephosphonic acid) (EDTMP), hexamethylenediamine-tetrakis(methylenephosphonic acid) (HDTMP), octamethylenediamine-tetrakis(methylenephosphonic acid) (ODTMP), and dodecamethylenediamine-tetrakis(methylenephosphonic acid) (DDTMP) have been used as additives. It was found that they are very effective retardants for the crystallization of calcium sulfate dihydrate. The inhibition efficiency is directly proportional to the number of methylene groups in the organic chain that connects the amino-bis(methylenephosphonate) moieties. The degree of inhibition of crystallization was measured as an increase in induction time and reduction in crystallization rate. Particle size and crystal morphology were determined with a particle-sizer and scanning electron microscopy. According to experimental results, phosphonate additives tested in this study are very effective retardants for the formation of calcium sulfate dihydrate scale. The crystal structure of [Ca(EDTMP)(H2O)2]·H2O is also reported. This is a one-dimensional coordination polymer in which EDTMP acts as both a bidentate chelate and a bridge for Ca2+ centers.
Co-reporter:Konstantinos D. Demadis, Eleni Barouda, Hong Zhao, Raphael G. Raptis
Polyhedron 2009 28(15) pp: 3361-3367
Publication Date(Web):
DOI:10.1016/j.poly.2009.05.050
Co-reporter:Rosario M.P. Colodrero;Aurelio Cabeza Dr.;Pascual Olivera-Pastor Dr.;Antonia Infantes-Molina Dr.;Eleni Barouda ;Miguel A.G. Ara
Chemistry - A European Journal 2009 Volume 15( Issue 27) pp:6612-6618
Publication Date(Web):
DOI:10.1002/chem.200900558
Co-reporter:Konstantinos D. Demadis, Maria Papadaki, Raphael G. Raptis and Hong Zhao
Chemistry of Materials 2008 Volume 20(Issue 15) pp:4835
Publication Date(Web):July 12, 2008
DOI:10.1021/cm801004w
Reactions of M2+ (M = Mg2+ (1), Ca2+ (2), Sr2+ (3), or Ba2+ (4)) salts with R,S-hydroxyphosphonoacetic acid (HPAA) in aqueous solutions of pH 2.0−2.7 at a 1:1 ratio yield hydrated M−HPAA layered or three-dimensional coordination polymers with varying degrees of hydration (metal-coordinated water or lattice water). The crystal structures of 3 (two different phases, 3a and 3b, formed at slightly different pH) and 4 have been determined by single-crystal X-ray crystallography. Both enantiomers (R and S) of HPAA are incorporated in these metal−HPAA materials. Compounds were also characterized by a plethora of other techniques (ATR-IR, SEM, TGA, elemental analyses, powder XRD). Corrosion experiments were carried out at pH 2.0 and 7.3 to study the effect of combinations of externally added Sr2+ or Ba2+ and HPAA (1:1 ratio) on corrosion rates of carbon steel. It was found that at pH 2.0 Sr/HPAA or Ba/HPAA 1:1 combinations are not able to inhibit corrosion. However, at pH 7.3 quantitative corrosion inhibition is achieved. Anticorrosion films were studied by FT-IR, EDS, and XRF. These amorphous (by XRD) inorganic−organic protective coatings are composed of Sr2+ or Ba2+ and HPAA in a 1:1 ratio and are identical to Sr−HPAA or Ba−HPAA materials synthesized at pH 7.3 and different from those synthesized at pH 2.0−2.7. Structure elucidation was not possible because they are amorphous.
Co-reporter:Bora Akın, Mualla Öner, Yasemin Bayram and Konstantinos D. Demadis
Crystal Growth & Design 2008 Volume 8(Issue 6) pp:1997
Publication Date(Web):April 29, 2008
DOI:10.1021/cg800092q
In this work, the effect of a biodegradable, environmentally friendly polysaccharide-based polycarboxylate, carboxymethyl inulin (CMI), on the crystal growth kinetics of calcium oxalate was studied at 37 °C. CMI is produced by carboxymethylation of inulin, the latter extracted from chicory roots. The spontaneous crystallization method was utilized to investigate the crystallization kinetics of calcium oxalate (CaC 2O 4, CaOx). The experimental results show that the retardation in mass transport in the growth process is controlled by the carboxylation degree of CMI and also its concentration. Our studies also indicate that polymers were effective in directing calcium oxalate crystallization from calcium oxalate monohydrate (COM) to calcium oxalate dihydrate (COD). Comparisons with the effects of polyacrylate (PAA) additive, which was also included in our experiments, show that PAA is a more effective inhibitor than CMI-15 and CMI-20, and comparable to CMI-25.
Co-reporter:Konstantinos D. Demadis, Maria Papadaki, Raphael G. Raptis, Hong Zhao
Journal of Solid State Chemistry 2008 Volume 181(Issue 3) pp:679-683
Publication Date(Web):March 2008
DOI:10.1016/j.jssc.2007.12.034
Reactions of Mg2+ (1), Ca2+ (2), Sr2+ (3), or Ba2+ (4) salts with hydroxyphosphonoacetic acid (HPAA) at a 1:1 ratio yield M-HPAA layered coordination polymers. The crystal structures of 3 (two phases) and 4 have been determined by single crystal X-ray crystallography. Both stereoisomers (R and S) of HPAA are incorporated in the metal-HPAA materials. Synergistic combinations of Sr2+ or Ba2+ and HPAA at pH 7.3 are effective corrosion inhibitors for carbon steel, but are ineffective at pH 2.0.Syntheses, characterization and crystal structures of metal-hydroxyphosphonoacetate hybrids are reported (Metal=Sr, Ba). 2D and 3D materials were prepared. Their anti-corrosion effects were studied at pH 2.0 and 7.3. It was found that anti-corrosion efficiency was demonstrated only at pH 7.3.
Co-reporter:Konstantinos D. Demadis, Antonia Ketsetzi, Konstantinos Pachis and Viviana M. Ramos
Biomacromolecules 2008 Volume 9(Issue 11) pp:
Publication Date(Web):October 23, 2008
DOI:10.1021/bm800872n
This article reports the inhibitory effects of phosphonated chitosan (PCH, synthesized from chitosan (CHS) by a Mannich-type reaction) on the in vitro silicic acid condensation. In particular, the ability of PCH to retard silicic acid condensation in aqueous supersaturated solutions at circumneutral pH is studied. Furthermore, the effect of anionic carboxymethyl inulin (CMI) polyelectrolyte on the inhibitory activity of PCH is systematically studied. It was discovered that when PCH is added in dosages up to 150 ppm, it can inhibit silicic acid condensation, thereby maintaining soluble silicic acid up to 300 ppm (for 8 h, from a 500 ppm initial stock solution). The addition of CMI to working solutions that already contain PCH can further enhance the inhibitory action of PCH. A combination of 150 ppm PCH and 100 ppm CMI maintains 400 ppm soluble silicic acid for 8 h. PCH and CMI combinations also affect colloidal silica particle morphology.
Co-reporter:Konstantinos D Demadis
Journal of Chemical Technology and Biotechnology 2005 Volume 80(Issue 6) pp:630-640
Publication Date(Web):10 MAR 2005
DOI:10.1002/jctb.1242
Dendrimers have attracted immense attention during the last decade due to their interesting properties both from a basic and an applied research viewpoint. Encapsulation of metal nanoparticles for catalysis, drug delivery and light harvesting are only some applications of dendrimers that are breaking new ground. A novel application of dendrimer technology is described in the present paper that relates to industrial water treatment. Industrial water systems often suffer from undesirable inorganic deposits. These can form either in the bulk or on metallic surfaces, such as heat exchangers or pipelines. Silica (SiO2) scale formation and deposition is a major problem in high-silica-containing cooling waters. Scale prevention rather than removal is highly desired. In this paper, benchtop screening tests on various silica inhibition chemistries are reported, with emphasis on materials with a dendrimeric structure. Specifically, the inhibition properties of commercially available STARBURST® polyaminoamide (PAMAM) dendrimers generations 0.5, 1, 1.5, 2, and 2.5 are investigated in detail together with other commonly-used scale inhibitors. Experimental results show that inhibition efficiency largely depends on structural features of PAMAM dendrimers such as generation number and nature of the end groups. PAMAM dendrimers are effective inhibitors of silica scale growth at 40 ppm dosage levels. PAMAM dendrimers also act as silica nucleators, forming SiO2–PAMAM composites. This occurs because the SiO2 formed by incomplete inhibition interacts with cationic PAMAM-1 and -2. The general scope of silica formation and inhibition in industrial waters is also discussed. Copyright © 2005 Society of Chemical Industry
Co-reporter:Konstantinos D. Demadis, Peter Baran
Journal of Solid State Chemistry 2005 Volume 178(Issue 7) pp:2399-2400
Publication Date(Web):July 2005
DOI:10.1016/j.jssc.2005.05.014
Co-reporter:Konstantinos D. Demadis, Peter Baran
Journal of Solid State Chemistry 2004 Volume 177(Issue 12) pp:4768-4776
Publication Date(Web):December 2004
DOI:10.1016/j.jssc.2004.07.042
Aminomethylene phosphonates are important scale inhibitors applied in diverse areas of technology. This study adds to the existing body of information on this subject and reports the crystal and molecular structures of tetrasodium 2-hydroxyethylamino-bis(methylene-phosphonate) decahydrate ([Na4(HOCH2CH2N(CH2PO3)2)]·10H2O, 1). The crystal structure of 1 could be described as two-dimensional polymeric layered structure hydrogen bonded into a 3D supramolecular polymeric network. The structure of the tetraanion consists of a “three-arm” backbone stemming from the N atom. Two “arms” are deprotonated methylene phosphonate (–CH2PO32−) moieties and the third is a hydroxyethyl (–CH2CH2OH) moiety. One Na cation forms an intramolecular complex with two oxygens from separate phosphonate groups, a hydroxyl oxygen, the nitrogen and two lattice water molecules. The position of this Na cation points to a possible coordination site for Ca in a proposed Ca–HEABMP complex (HEABMP=2-hydroxyethylamino-bis(methylene-phosphonate).The crystal structure of [Na4(HOCH2CH2N(CH2PO3)2)]·10H2O is a two-dimensional polymeric layered structure hydrogen bonded into a 3D supramolecular polymeric network. The structure of the tetraanion consists of a “three-arm” backbone stemming from the N atom. Two “arms” are deprotonated methylene phosphonate (-CH2PO32−) moieties and the third is a hydroxyethyl (-CH2CH2OH) moiety. One Na cation forms an intramolecular complex with two oxygens from separate phosphonate groups, a hydroxyl oxygen, the nitrogen and two lattice water molecules.
Co-reporter:Eleftheria Mavredaki, Aggeliki Stathoulopoulou, Eleftheria Neofotistou, Konstantinos D. Demadis
Desalination (10 June 2007) Volume 210(Issues 1–3) pp:257-265
Publication Date(Web):10 June 2007
DOI:10.1016/j.desal.2006.05.050
Supersaturated process waters high in silicates frequently result in deposition of colloidal silica or metal silicate salts. Silica cannot be inhibited by conventional phosphonate mineral scale inhibitors. Chemical cleaning poses hazards and requires operational shut-downs. This paper is focused on a dual approach for silica scale control, inhibition of colloidal silica formation and colloidal silica dissolution in water technology applications by use of designed chemical approaches. The additives used for silica inhibition were polyaminoamide dendrimers (PAMAM) and polyethyleneimine (PEI), in combination with carboxymethyl inulin (CMI) and polyacrylate (PAA) polymers. In principle, silica inhibition is a function of time and inhibitor dosage. Amine-terminated PAMAM-1 and 2 dendrimers as well as PEI combined with anionic polymers, such as CMI and PAA, seem to have a significant inhibitory effect on silica formation, most likely at its earlier stages where the reaction products are oligomeric silicates. CMI and PAA assist the inhibitory action of PAMAM-1 and 2 and PEI by alleviating formation of insoluble SiO2-PAMAM precipitates. This most likely occurs by partial neutralization of the positive charge that exists in –NH+3 surface groups. Increase of anionic polymer dosage above a certain threshold has a detrimental effect on the activity of the cationic inhibitors. In that case the polymer’s negative charge “overwhelms” the cationic charge of the inhibitor and poisons its inhibition ability. For silica dissolution, acetic, oxalic, citric acids, histidine and phenylalanine were used as potential replacements of ammonium bifluoride (NH4F·HF). Silica dissolution is dependent in a rather unpredictable fashion on the structure of the dissolver, time and dosage. This paper continues our research efforts in the discovery, design and application of antiscalant additives that have mild environmental impact. These chemicals are also known as “green additives”.
Co-reporter:Rosario M. P. Colodrero, Pascual Olivera-Pastor, Enrique R. Losilla, Miguel A. G. Aranda, Laura Leon-Reina, Maria Papadaki, Alistair C. McKinlay, Russell E. Morris, Konstantinos D. Demadis and Aurelio Cabeza
Dalton Transactions 2012 - vol. 41(Issue 14) pp:NaN4051-4051
Publication Date(Web):2012/01/25
DOI:10.1039/C2DT11992G
A new flexible ultramicroporous solid, La(H5DTMP)·7H2O (1), has been crystallized at room temperature using the tetraphosphonic acid H8DTMP, hexamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid). Its crystal structure, solved by synchrotron powder X-ray diffraction, is characterised by a 3D pillared open-framework containing 1D channels filled with water. Upon dehydration, a new related crystalline phase, La(H5DTMP) (2) is formed. Partial rehydration of 2 led to La(H5DTMP)·2H2O (3). These new phases contain highly corrugated layers showing different degrees of conformational flexibility of the long organic chain. The combination of the structural study and the gas adsorption characterization (N2 and CO2) suggests an ultramicroporous flexible framework. NO isotherms are indicative of a strong irreversible adsorption of NO within the pores. Impedance data indicates that 1 is a proton-conductor with a conductivity of 8 × 10−3 S cm−1 at 297 K and 98% of relative humidity, and an activation energy of 0.25 eV.
