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CHAPTER 1. Applications of Smart Multifunctional Tissue Engineering Scaffolds. SMART MATERIALS FOR TISSUE ENGINEERING 2017. [DOI: 10.1039/9781788010542-00001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Abstract
Highly cross-linked polystyrene nanoparticles bearing functional porphyrin moieties were synthesized by emulsion free-radical copolymerization. The polystyrene–porphyrin nanoparticles exhibit exceptionally high CO2/CH4 selectivity values, attributed to the presence of the porphyrin macrocyclic cavities in the material, which renders them attractive for use in gas separation and gas capture applications.
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A Unique Dinuclear Mixed V(V) Oxo-peroxo Complex in the Structural Speciation of the Ternary V(V)-Peroxo-citrate System. Potential Mechanistic and Structural Insight into the Aqueous Synthetic Chemistry of Dinuclear V(V)-Citrate Species with H2O2. Inorg Chem 2011; 50:11423-36. [DOI: 10.1021/ic201204s] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Probing for missing links in the binary and ternary V(V)–citrate–(H2O2) systems: Synthetic efforts and in vitro insulin mimetic activity studies. J Inorg Biochem 2009; 103:503-16. [DOI: 10.1016/j.jinorgbio.2008.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/21/2008] [Accepted: 12/30/2008] [Indexed: 01/19/2023]
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Aqueous V(V)-Peroxo-Amino Acid Chemistry. Synthesis, Structural and Spectroscopic Characterization of Unusual Ternary Dinuclear Tetraperoxo Vanadium(V)-Glycine Complexes. Inorg Chem 2008; 48:476-87. [DOI: 10.1021/ic801427b] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Synthesis, isolation, spectroscopic and structural characterization of a new pH complex structural variant from the aqueous vanadium(V)-peroxo-citrate ternary system. Inorganica Chim Acta 2006. [DOI: 10.1016/j.ica.2006.07.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Interactions of vanadium(V)-citrate complexes with the sarcoplasmic reticulum calcium pump. J Inorg Biochem 2005; 99:2355-61. [PMID: 16219359 DOI: 10.1016/j.jinorgbio.2005.09.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 09/05/2005] [Accepted: 09/07/2005] [Indexed: 02/07/2023]
Abstract
Among the biotargets interacting with vanadium is the calcium pump from the sarcoplasmic reticulum (SR). To this end, initial research efforts were launched with two vanadium(V)-citrate complexes, namely (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)].6H(2)O and (NH(4))(6)[V(2)O(2)(O(2))(2)(C(6)H(4)O(7))(2)].4H(2)O, potentially capable of interacting with the SR calcium pump by combining kinetic studies with (51)V NMR spectroscopy. Upon dissolution in the reaction medium (concentration range: 4-0.5mM), both vanadium(V):citrate (VC) and peroxovanadium(V):citrate (PVC) complexes are partially converted into vanadate oligomers. A 1mM solution of the PVC complex, containing 184microM of the PVC complex, 94microM oxoperoxovanadium(V) (PV) species, 222microM monomeric (V1), 43microM dimeric (V2) and 53microM tetrameric (V4) species, inhibits Ca(2+) accumulation by 75 %, whereas a solution of the VC complex of the same vanadium concentration, containing 98microM of the VC complex, 263microM monomeric (V1), 64microM dimeric (V2) and 92microM tetrameric (V4) species inhibits the calcium pump activity by 33 %. In contrast, a 1 mM metavanadate solution, containing 460microM monomeric (V1), 90.2microM dimeric (V2) and 80microM tetrameric (V4) species, has no effect on Ca(2+) accumulation. The NMR signals from the VC complex (-548.0ppm), PVC complex (-551.5ppm) and PV (-611.1ppm) are broadened upon SR vesicle addition (2.5mg/ml total protein). The relative order for the half width line broadening of the NMR signals, which reflect the interaction with the protein, was found to be V4>PVC>VC>PV>V2=V1=1, with no effect observed for the V1 and V2 signals. Putting it all together the effects of two vanadium(V)-citrate complexes on the modulation of calcium accumulation and ATP hydrolysis by the SR calcium pump reflected the observed variable reactivity into the nature of key species forming upon dissolution of the title complexes in the reaction media.
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pH-Specific Synthesis of a Dinuclear Vanadium(V)−Peroxo−Citrate Complex in Aqueous Solutions: pH-Dependent Linkage, Spectroscopic and Structural Correlations with Other Aqueous Vanadium(V)−Peroxo−Citrate and Non-Peroxo Species. Inorg Chem 2004; 43:2895-905. [PMID: 15106977 DOI: 10.1021/ic034283i] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aqueous reactions of V2O5 or VCl3 in the presence of the physiological citric acid and hydrogen peroxide, in a pH specific fashion, afforded a new vanadium(V)-peroxo-citrate material isolated in a pure crystalline form. Elemental analysis pointed to the molecular formulation (NH4)6[V(V)2O2(O2)2(C6H4O7)2].4.5H2O (1). Complex 1 was further characterized by UV-vis, FT-IR, and X-ray crystallography. Compound 1 crystallizes in the monoclinic space group C2/c with a = 12.391(5) A, b = 15.737(7) A, c = 17.102(7) A, beta = 110.84(1) degrees, V = 3117(1) A3, and Z = 4. The structure of the anionic assembly consists of a planar V(V)2O2 core with two fully deprotonated citrates bound to it through the central carboxylate and alkoxide moieties as well as one of the terminal carboxylate groups. The presence of one peroxide group attached to each vanadium(V) renders the geometry around each metal center pentagonal bipyramidal. Key structural and spectroscopic features of 1 correlate with those seen in the peroxo congener and low-pH analogue (NH4)2[V(V)2O2(O2)2(C6H6O7)2].2H2O (3), in which all terminal carboxylate groups are protonated. In solution, simple pH-dependent transformation of 1 to 3 attests to their participation in the requisite speciation and potentiates the presence of other similar peroxo analogues not yet isolated and characterized. The reactivity of 1 through transformation reactions, yielding a plethora of well-characterized species, establishes a linkage among various species with the same or different vanadium oxidation states. Collectively, the data reflect soluble forms of vanadium with peroxide and citrate that contribute to the requisite pH-dependent distribution of that metal ion and likely influence biological processes.
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Systematic studies on pH-dependent transformations of dinuclear vanadium(V)-citrate complexes in aqueous solutions. A perspective relevance to aqueous vanadium(V)-citrate speciation. J Inorg Biochem 2003; 93:161-73. [PMID: 12576278 DOI: 10.1016/s0162-0134(02)00563-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Vanadium(V) involvement in interactions with physiological ligands in biological media prompted us to delve into the systematic pH-dependent synthesis, spectroscopic characterization, and perusal of chemical properties of arising aqueous vanadium(V)-citrate species in the requisite system. To this end, facile reactions led to dinuclear complexes (NH(4))(4)[V(2)O(4)(C(6)H(5)O(7))(2)].4H(2)O (1) and (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)].6H(2)O (2). Complex 1 and 2 were characterized by elemental analysis, FT-IR and X-ray crystallography. Complex 1 crystallizes in the monoclinic space group C2/c with a=16.998(5) A, b=16.768(5) A, c=9.546(3) A, beta=105.22(1) degrees, V=2625(1) A(3), and Z=4. Complex 2 crystallizes in the triclinic space group P1;, with a=9.795(4) A, b=9.942(4) A, c=9.126(3) A, alpha=90.32(1) degrees, beta=111.69(1) degrees, gamma=108.67(1) degrees, V=774.5(5) A(3), and Z=1. The structures of 1 and 2 were consistent with the presence of a V(V)(2)O(2) core, to which citrate ligands of differing protonation state were bound in a coordination mode consistent with past observations. Ultimately, the aqueous pH dependent transformations of a series of three dinuclear complexes, 1, 2 and (NH(4))(2)[V(2)O(4)(C(6)H(6)O(7))(2)].2H(2)O (3), all isolated at pH values from 3 to 7.5, were explored and revealed an important interconnection among all species. Collectively, pH emerged as a determining factor of structural attributes in all three complexes, with the adjoining acid-base chemistry unfolding around the stable V(V)(2)O(2) core. The results point to the participation of all three species in aqueous vanadium(V)-citrate speciation, and may relate the site-specific protonations-deprotonations on the dinuclear complexes to potential biological processes involving vanadium(V) and physiological ligand targets.
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Reactivity investigation of dinuclear vanadium(IV,V)-citrate complexes in aqueous solutions. A closer look into aqueous vanadium-citrate interconversions. Inorg Chem 2002; 41:7015-23. [PMID: 12495339 DOI: 10.1021/ic020323r] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Well-known vanadium(IV)- and vanadium(V)-citrate complexes have been employed in transformations involving vanadium redox as well as nonredox processes. The employed complexes include K(2)[V(2)O(4)(C(6)H(6)O(7))(2)] x 4H(2)O, K(4)[V(2)O(4)(C(6)H(5)O(7))(2)] x 5.6H(2)O, K(2)[V(2)O(2)(O(2))(2)(C(6)H(6)O(7))(2)] x 2H(2)O, K(4)[V(2)O(2)(C(6)H(4)O(7))(2)] x 6H(2)O, K(3)[V(2)O(2)(C(6)H(4)O(7))(C(6)H(5)O(7))] x 7H(2)O, (NH(4))(4)[V(2)O(2)(C(6)H(4)O(7))(2)] x 2H(2)O, and (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)] x 6H(2)O. Reactions toward hydrogen peroxide at different vanadium(IV,V):H(2)O(2) ratios were crucial in delineating the routes leading to the interconversion of the various species. Equally important thermal transformations were critical in showing the linkage between pairs of dinuclear vanadium-citrate peroxo as well as nonperoxo complexes, for which the important vanadium(V)-assisted oxidative decarboxylation, leading to reduction of vanadium(V) to vanadium(IV), seemed to be a plausible pathway in place for all the cases examined. FT-IR spectroscopy and X-ray crystallography were instrumental in the identification of the arising products of all investigated reactions. Collectively, the data support the existence of chemical links between different and various structural forms of dinuclear vanadium(IV,V)-citrate complexes in aqueous media. Furthermore, in corroboration of past studies, the examined interconversions lend credence to the notion that the involved species are active participants in the respective aqueous distributions of the metal ion in the presence of the physiological ligand citrate. The concomitant significance of structure-specific species relating to soluble and potentially bioavailable forms of vanadium is mentioned.
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A new dinuclear vanadium(V)-citrate complex from aqueous solutions. Synthetic, structural, spectroscopic, and pH-dependent studies in relevance to aqueous vanadium(V)-citrate speciation. Inorg Chem 2002; 41:3850-8. [PMID: 12132908 DOI: 10.1021/ic010971v] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vanadium interactions with low molecular mass binders in biological fluids entail the existence of vanadium species with variable chemical and biological properties. In the course of efforts to elucidate the chemistry related to such interactions, we have explored the oxidative chemistry of vanadium(III) with the physiologically relevant tricarboxylic citric acid. Aqueous reactions involving VCl(3) and anhydrous citric acid, at pH approximately 7, resulted in blue solutions. Investigation into the nature of the species arising in those solutions revealed, through UV/visible and EPR spectroscopies, oxidation of vanadium(III) to vanadium(IV). Further addition of H(2)O(2) resulted in the oxidation of vanadium(IV) to vanadium(V), and the isolation of a new vanadium(V)-citrate complex in the form of its potassium salt. Analogous reactions with K(4)[V(2)O(2)(C(6)H(4)O(7))(2)].6H(2)O and H(2)O(2) or V(2)O(5) and citrate at pH approximately 5.5 afforded the same material. Elemental analysis pointed to the molecular formulation K(4)[V(2)O(4)(C(6)H(5)O(7))(2)].5.6H(2)O (1). Complex 1 was further characterized by FT-IR and X-ray crystallography. 1 crystallizes in the triclinic space group P(-)1, with a = 11.093(4) A, b = 9.186(3) A, c = 15.503(5) A, alpha = 78.60(1) degrees, beta = 86.16(1) degrees, gamma = 69.87(1) degrees, V = 1454.0(8) A(3), and Z = 2. The X-ray structure of 1 reveals the presence of a dinuclear vanadium(V)-citrate complex containing a V(V)(2)O(2) core. The citrate ligands are triply deprotonated, and as such they bind to vanadium(V) ions, thus generating a distorted trigonal bipyramidal geometry. Binding occurs through the central alkoxide and carboxylate groups, with the remaining two terminal carboxylates being uncoordinated. One of those carboxylates is protonated and contributes to hydrogen bond formation with the deprotonated terminal carboxylate of an adjacent molecule. Therefore, an extended network of hydrogen-bonded V(V)(2)O(2)-core-containing dimers is created in the lattice of 1. pH-dependent transformations of 1 in aqueous media suggest its involvement in a web of vanadium(V)-citrate dinuclear species, consistent with past solution speciation studies investigating biologically relevant forms of vanadium.
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Vanadium(IV)-citrate complex interconversions in aqueous solutions. A pH-dependent synthetic, structural, spectroscopic, and magnetic study. Inorg Chem 2001; 40:5772-9. [PMID: 11681884 DOI: 10.1021/ic010276n] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Citrate is abundantly encountered in biological fluids as a natural metal ion chelator. Vanadium participates in biological processes as a catalyst in the active sites of metalloenzymes, as a metabolic regulator, as a mitogenic activator, and as an insulin-mimicking agent. Thus, vanadium chemistry with natural chelators, such as citrate, may have immediate implications on its role in a cellular milieu, and its action as a biological agent. In an effort to comprehend the aqueous chemistry of one of vanadium's oxidation states, namely, V(IV), implicated in its biological activity, reactions of VCl(3) and citric acid were pursued in water and led to V(IV)-citrate complexes, the nature and properties of which depend strongly on the solution pH. Analytical, FT-IR, UV/vis, EPR, and magnetic susceptibility data supported the formulation of X(4)[[VO(H(-1)Cit)](2)] x nH(2)O (H(-1)Cit = C(6)H(4)O(7)(4-); X = K(+), n = 6 (1); X = Na(+), n = 12 (2); X = NH(4)(+), n = 2 (3)) (pH approximately 8) and X(3)[[V(2)O(2)(H(-1)Cit)(Cit)]] x nH(2)O (X = K(+), n = 7 (4)) (pH approximately 5). Complex 2 crystallizes in space group P2(1)/c, a = 11.3335(9) A, b = 15.788(1) A, c = 8.6960(6) A, beta = 104.874(3) degrees, V = 1503.8(2), Z = 2. Complex 3 crystallizes in space group P one macro, a = 9.405(1) A, b = 10.007(1) A, c = 13.983(2) A, alpha = 76.358(4) degrees, beta = 84.056(4) degrees, gamma = 66.102(4) degrees, V = 1169.2(3), Z = 2. Complex 4 crystallizes in space group P2(1)nb, a = 9.679(4) A, b = 19.618(8) A, c = 28.30(1) A, V = 5374.0(4), Z = 8. The X-ray structures of 1-4 are V(2)O(2) dimers, with the citrate displaying varying coordination numbers and modes. 1 exhibits a small ferromagnetic interaction, whereas 4 exhibits an antiferromagnetic interaction between the V(IV) ions. 1 and 4 interconvert with pH, thus rendering the pH a determining factor promoting variable structural, electronic, and magnetic properties in V(IV)-citrate species. The observed aqueous behavior of 1-4 is consistent with past solution speciation studies, and contributes to the understanding of significant aspects of the biologically relevant vanadium(IV)-citrate chemistry.
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pH-dependent investigations of vanadium(V)-peroxo-malate complexes from aqueous solutions. In search of biologically relevant vanadium(V)-peroxo species. Inorg Chem 2001; 40:3711-8. [PMID: 11442368 DOI: 10.1021/ic000894o] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The established biochemical potential of vanadium has spurred considerable research interest in our lab, with specific focus on pertinent synthetic studies of vanadium(III) with a biologically relevant, organic, dicarboxylic acid, malic acid, in aqueous solutions. Simple reactions between VCl3 and malic acid in water, at different pH values, in the presence of H2O2, led to the crystalline dimeric complexes (Cat)4[VO(O2)(C4H3O5)]2*nH2O (Cat = K+, n = 4, 1; Cat = NH4+, n = 3, 2) and K2[VO(O2)(C4H4O5)]2*2H2O (3). All three complexes were characterized by elemental analysis, FT-IR, and UV/visible spectroscopies. Compound 1 crystallizes in the monoclinic space group P2(1)/c, with a = 8.380(5) A, b = 9.252(5) A, c = 13.714(8) A, beta = 93.60(2) degrees, V = 1061(1) A3, and Z = 4. Compound 2 crystallizes in the triclinic space group P1, with a = 9.158(4) A, b = 9.669(4) A, c = 14.185(6) A, alpha = 104.81(1) degrees, beta = 90.31(1) degrees, gamma = 115.643(13) degrees, V = 1085.0(7) A(3), and Z = 2. Compound 3 crystallizes in the monoclinic space group P2(1)/c, with a = 9.123(8) A, b = 9.439(8) A, c = 10.640(9) A, beta = 104.58(3) degrees, V = 887(1) A3, and Z = 2. The X-ray structures showed that, in 1 and 2, the dimers consist of two (V(V)=O)2O2 rhombic units to which two malate ligands are attached. The ligands are triply deprotonated and, as such, they coordinate to vanadium(V), promoting a pentagonal bipyramidal geometry. In 3, the dimeric (V(V)=O)2O2 rhombic unit persists, with the two doubly deprotonated malate ligands coordinated to the vanadium(V) ions. UV/vis and EPR spectroscopic studies on the intermediate blue solutions of the synthesis reactions of 1-3 support the existence of vanadyl-containing dimeric species. These species further react with H2O2 to yield oxidation of V(IV)2O2 to V(V)2O2 and coordination of the peroxide to vanadium(V). From the collective data on 1-3, it appears that pH acts as a decisive factor in dictating the structural features of the isolated complexes. The details of the introduced structural differentiation in the reported complexes, and their potential relevance to vanadium(V) dicarboxylate systems in biological media are dwelled on.
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