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ABSTRACT: Synthetic efforts linked to the design of defined lattice dimensionality and architecture materials in the binary/ternary systems of Cu(II) with butylene diamine tetra(methylene phosphonic acid) (H8BDTMP) and heterocyclic organic chelators (pyridine and 1,10-phenanthroline) led to the isolation of new copper organophosphonate compounds, namely, Na6[Cu2(BDTMP)(H2O)4]·[Cu2(BDTMP)(H2O)4]0.5·26H2O (1), [Cu2(H4BDTMP)(py)4]·2H2O (2), and [Cu2(H4BDTMP)(phen)2]n·6.6nH2O·1.5nMeOH (3). 1-3 are the first compounds isolated from the Cu(II)-BDTMP family of species. They were characterized by elemental analysis, spectroscopic techniques (FT-IR, UV-vis), magnetic susceptibility, TGA-DTG, cyclic voltammetry, and X-ray crystallography. The lattice in 1 reveals the presence of discrete dinuclear Cu(II) units bound to BDTMP(8-) and water molecules in a square pyramidal geometry. The molecular lattice of 2 reveals the presence of ternary dinuclear assemblies of Cu(II) ions bound to H4BDTMP(4-) and pyridine in a square pyramidal environment. The molecular lattice of 3 reveals the presence of dinuclear assemblies of Cu(II) ions bound to H4BDTMP(4-) and 1,10-phenanthroline in a square pyramidal environment, with the organophosphonate ligand serving as the connecting link to abutting dinuclear Cu(II) assemblies in a ternary polymeric system. The magnetic susceptibility data on 1, 2, and 3 suggest that compounds 1 and 3 exhibit a stronger antiferromagnetic behavior than 2, which is also confirmed from magnetization measurements. The physicochemical profiles of 1-3 (a) earmark the influence of the versatile H8BDTMP ligand as a metal ion binder on the chemical reactivity in binary and ternary systems of Cu(II) in aqueous and nonaqueous media and (b) denote the correlation of ligand hydrophilicity, aromaticity, denticity, charge, and H-bonding interactions with emerging defined Cu(II)-H8BDTMP structures of distinct lattice identity and spectroscopic-magnetic properties. Collectively, such structural and chemical factors formulate the interplay and contribution of binary and ternary interactions to lattice architecture and specified properties of new Cu(II)-organophosphonate materials with defined 2D-3D dimensionality.
Inorganic Chemistry 04/2013; · 4.60 Impact Factor
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ABSTRACT: The mixed valence Co(II)/Co(III) tetranuclear clusters [Co(II)(2)Co(III)(2)(tea)(2)(pyr)(2)(NO(3))(4)]·2CH(3)CN (), [Co(II)(2)Co(III)(2)(μ(3)-OH)(2)(Htea)(2)(bpy)(4)](NO(3))(4) (), and [Co(II)(2)Co(III)(2)(μ(3)-OH)(2)(Htea)(2)(phen)(4)](NO(3))(4)·2CH(3)CN·2CH(3)OH () are described where tea and Htea are the fully and the doubly deprotonated form of triethanolamine, while as N-donors are pyridine, 2,2'-bipyridine and 1,10-phenanthroline. Complexes contain the Co(II)(2)Co(III)(2)O(6) core and can be described as defective dicubanes with different imperfectness. In , the central rhombic core Co(2)O(2) is occupied by two Co(III) ions while the external cobalt atoms display Co(II) oxidation states; meanwhile and exhibit a reversal in their Co(II)(2)Co(III)(2) oxidation state distribution. Two different theoretical models were used to explain the magnetic behavior: (i) spin-spin interaction model with local anisotropy terms where S = 3/2 for both metal centers and (ii) an anisotropic spin-spin interaction model applicable in the low temperature range (T < 40 K) using effective spins (S(eff) = 1/2) for both metal centers. For a relatively strong next-nearest-neighbour antiferromagnetic exchange interaction between the Co(ii) centers which are connected via diamagnetic Co(iii) ion was found while for and the presence of ferromagnetic interaction is confirmed. The fitting results, concerning the first model, gave: J = 2.0(2)/3.2(2)/3.8(2) cm(-1), g = 2.35(1)/2.52(1)/2.57(1) and D = 11.0(1)/8.5(1)/7.8(1) cm(-1) while concerning the second model are: J(z) = -7.1(2)/19.2(2)/22.1(2) cm(-1), g(z) = 6.8(1)/8.1(1)/8.3(1), J(xy)/J(z) = 0.34(2)/0.11(2)/0.14(2), and g(xy)/g(z) = 0.52(2)/0.28(2)/0.36(2) for . X-Band EPR spectrum of has a very broad derivative centered at g = 5.3 while for and large g-variations were found in the range 20.0-1.0, indicative of an exchange interaction between Co(ii) ions.
Dalton Transactions 02/2013; · 3.84 Impact Factor
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ABSTRACT: Chromium is widespread in the environment and is used in ample industrial applications in abiotic and biological systems. Its ability to influence biological processes through interactions with biomolecules underscores its positive role as well as its toxic manifestations in higher organisms. In an attempt to understand its (bio)chemistry, research efforts were undertaken to explore the aqueous chemistry of Cr(III) with the low molecular mass physiological ligand, quinic acid. pH-Specific synthesis in the binary Cr(III)–quinato system led to the isolation of Na[Cr3O(C7H11O6)6(H2O)3]·(NO3)1.5·(OH)0.5·6H2O (1). 1 crystallizes in the monoclinic space group C2, with a = 32.16(1) Å, b = 14.076(7) Å, c = 15.083(5) Å, β = 95.53(1)°, V = 6796(5) Å3, and Z = 4. The structure of 1 reveals a trinuclear assembly of Cr(III) with quinate. The assembly consists of a [Cr3O] core containing a triply bound oxido O2− ligand holding the three Cr(III) ions together and six coordinated quinato ligands linking contiguously the three Cr(III) centers in a peripheral cyclic fashion. Each ligand binds two abutting Cr(III) metal ions through the carboxylato oxygens. The alcoholic groups of the quinates are not deprotonated and do not coordinate to the Cr(III) ions. The collective binding of Cr(III) with quinates in a 1:2 ratio leads to a distorted octahedral geometry around each metal center, with the sixth coordination site occupied by a water ligand. 1 was characterized by elemental analysis, spectroscopic (UV–Vis, FT-IR, ESI-MS, EPR), structural, thermal, cyclic voltammetric, and magnetic susceptibility studies. The collective structural and spectroscopic techniques point out the distinct properties of 1 in the solid state and in solution, thus exemplifying the physicochemical profile of that compound in the overall structural speciation scheme of the binary Cr(III)–quinato system. Solid state-solution structural correlation suggests retention of the trinuclear core complex of 1 in solution, also supported by ESI-MS, thereby lending credence to the detailed aqueous speciation studies in the binary Cr(III)–quinato system investigated in the employed pH range. The unique behavior of 1 in comparison to other known trinuclear [Cr3O]-containing compounds (a) signifies the importance of binary interactions of Cr(III) with hydroxycarboxylic acids, and (b) necessitates further perusal of analogous binary systems of Cr(III), that will enable understanding of the factors influencing the role of the specific metal ion in the development of (bio)chemical reactivity in biological systems and abiotic materials applications.
Polyhedron 01/2013; 52:598-609. · 2.06 Impact Factor
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ABSTRACT: Hydrothermal pH-specific reactivity in the binary/ternary systems of Pb(II) with the carboxylic acids N-hydroxyethyl-iminodiacetic acid (Heida), 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (Dpot), and 1,10-phenanthroline (Phen) afforded the new well-defined crystalline compounds [Pb(Heida)](n)·nH(2)O(1), [Pb(Phen)(Heida)]·4H(2)O(2), and [Pb(3)(NO(3))(Dpot)](n)(3). All compounds were characterized by elemental analysis, FT-IR, solution or/and solid-state NMR, and single-crystal X-ray diffraction. The structures in 1-2 reveal the presence of a Pb(II) center coordinated to one Heida ligand, with 1 exhibiting a two-dimensional (2D) lattice extending to a three-dimensional (3D) one through H-bonding interactions. The concurrent aqueous speciation study of the binary Pb(II)-Heida system projects species complementing the synthetic efforts, thereby lending credence to a global structural speciation strategy in investigating binary/ternary Pb(II)-Heida/Phen systems. The involvement of Phen in 2 projects the significance of nature and reactivity potential of N-aromatic chelators, disrupting the binary lattice in 1 and influencing the nature of the ultimately arising ternary 3D lattice. 3 is a ternary coordination polymer, where Pb(II)-Dpot coordination leads to a 2D metal-organic-framework material with unique architecture. The collective physicochemical properties of 1-3 formulate the salient features of variable dimensionality metal-organic-framework lattices in binary/ternary Pb(II)-(hydroxy-carboxylate) structures, based on which new Pb(II) materials with distinct architecture and spectroscopic signature can be rationally designed and pursued synthetically.
Inorganic Chemistry 08/2012; 51(17):9282-96. · 4.60 Impact Factor
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ABSTRACT: Vanadium involvement in cellular processes requires deep understanding of the nature and properties of its soluble and bioavailable forms arising in aqueous speciations of binary and ternary systems. In an effort to understand the ternary vanadium-H(2)O(2)-ligand interactions relevant to that metal ion's biological role, synthetic efforts were launched involving the physiological ligands betaine (Me(3)N(+)CH(2)CO(2)(-)) and H(2)O(2). In a pH-specific fashion, V(2)O(5), betaine, and H(2)O(2) reacted and afforded three new, unusual, and unique compounds, consistent with the molecular formulation K(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}]·H(2)O (1), (NH(4))(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}]·0.75H(2)O (2), and {Na(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}(2)]}(n)·4nH(2)O (3). All complexes 1-3 were characterized by elemental analysis; UV/visible, FT-IR, Raman, and NMR spectroscopy in solution and the solid state; cyclic voltammetry; TGA-DTG; and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium-tetraperoxido-betaine complexes containing [(V(V)═O)(O(2))(2)] units interacting through long V-O bonds. The two V(V) ions are bridged through the oxygen terminal of one of the peroxide groups bound to the vanadium centers. The betaine ligand binds only one of the two V(V) ions. In the case of the third complex 3, the two vanadium centers are not immediate neighbors, with Na(+) ions (a) acting as efficient oxygen anchors and through Na-O bonds holding the two vanadium ions in place and (b) providing for oxygen-containing ligand binding leading to a polymeric lattice. In 1 and 3, interesting 2D (honeycomb) and 1D (zigzag chains) topologies of potassium nine-coordinate polyhedra (1) and sodium octahedra (3), respectively, form. The collective physicochemical properties of the three ternary species 1-3 project the chemical role of the low molecular mass biosubstrate betaine in binding V(V)-diperoxido units, thereby stabilizing a dinuclear V(V)-tetraperoxido dianion. Structural comparisons of the anions in 1-3 with other known dinuclear V(V)-tetraperoxido binary anionic species provide insight into the chemical reactivity of V(V)-diperoxido systems and their potential link to cellular events such as insulin mimesis and anitumorigenicity modulated by the presence of betaine.
Inorganic Chemistry 05/2012; 51(11):6056-69. · 4.60 Impact Factor
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ABSTRACT: Vanadium involvement in cellular processes requires deep understanding of the nature and properties of its soluble and bioavailable forms arising in aqueous speciations of binary and ternary systems. In an effort to understand the ternary vanadium–H2O2–ligand interactions relevant to that metal ion’s biological role, synthetic efforts were launched involving the physiological ligands betaine (Me3N+CH2CO2–) and H2O2. In a pH-specific fashion, V2O5, betaine, and H2O2 reacted and afforded three new, unusual, and unique compounds, consistent with the molecular formulation K2[V2O2(O2)4{(CH3)3NCH2CO2)}]·H2O (1), (NH4)2[V2O2(O2)4{(CH3)3NCH2CO2)}]·0.75H2O (2), and {Na2[V2O2(O2)4{(CH3)3NCH2CO2)}2]}n·4nH2O (3). All complexes 1–3 were characterized by elemental analysis; UV/visible, FT-IR, Raman, and NMR spectroscopy in solution and the solid state; cyclic voltammetry; TGA-DTG; and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium–tetraperoxido–betaine complexes containing [(VV═O)(O2)2] units interacting through long V–O bonds. The two V(V) ions are bridged through the oxygen terminal of one of the peroxide groups bound to the vanadium centers. The betaine ligand binds only one of the two V(V) ions. In the case of the third complex 3, the two vanadium centers are not immediate neighbors, with Na+ ions (a) acting as efficient oxygen anchors and through Na–O bonds holding the two vanadium ions in place and (b) providing for oxygen-containing ligand binding leading to a polymeric lattice. In 1 and 3, interesting 2D (honeycomb) and 1D (zigzag chains) topologies of potassium nine-coordinate polyhedra (1) and sodium octahedra (3), respectively, form. The collective physicochemical properties of the three ternary species 1–3 project the chemical role of the low molecular mass biosubstrate betaine in binding V(V)–diperoxido units, thereby stabilizing a dinuclear V(V)–tetraperoxido dianion. Structural comparisons of the anions in 1–3 with other known dinuclear V(V)–tetraperoxido binary anionic species provide insight into the chemical reactivity of V(V)–diperoxido systems and their potential link to cellular events such as insulin mimesis and anitumorigenicity modulated by the presence of betaine.
Inorganic Chemistry 01/2012; 51(11):6056-6096. · 4.60 Impact Factor
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ABSTRACT: Cu(II) is a metal ion, the aqueous chemistry of which with carboxylic acids draws intense interest, targeting
new materials and exemplifying diverse and unique structure–reactivity correlations. Driven by the
need to explore the interplay of the chemical interactions of Cu(II) with polycarboxylic acid substrates
and the association of such reactivity with lattice architecture and physicochemical properties, binary
and ternary systems of Cu(II) with 1,2,3,4-cyclobutane-tetracarboxylic acid (H4CBTC) and bipy (2,20-
bipyridine) were investigated. To this end, aqueous synthetic reactions of Cu(II) with H4CBTC, under
pH-specific conditions (pH 3), led to the isolation of the first species in the aforementioned binary system
[Cu2(CBTC)(H2O)4)]n�2nH2O (1). Aqueous synthetic chemical reactivity in the ternary Cu(II)–H4CBTC–bipy
system led to the isolation of the 1D polymer [Cu(NO3)2(bipy)]n (2). Complexes 1 and 2 were characterized
by elemental analysis, spectroscopic techniques (EPR, FT-IR, UV–Vis and luminescence (2)), magnetic
susceptibility, cyclic voltammetry (2) and thermogravimetric studies, and X-ray crystallography. The
molecular lattice in 1 reveals the presence of Cu(II) units bound to (a) 1,2,3,4-cyclobutane-tetracarboxylate,
and (b) water molecules, in a tetragonal pyramidal geometry, thereby projecting the unique chemical
reactivity in the requisite system leading to a 3D lattice assembly. The presence of two types of channels
in the solid state lattice of variable hydrophilicity/hydrophobicity signifies their unique nature in the
coordination polymer and projects the importance of H2O and its H-bonding ability in the assembly of
1. The molecular lattice of 2 reveals the presence of Cu(II) ions bound to nitrate ions and 2,20-bipy in
an octahedral fashion, collectively leading to a 1D lattice assembly. The magnetic susceptibility and
solid-state EPR data on 1 and 2 are consistent with the presence of Cu(II) in a tetragonal pyramidal
and octahedral environment, respectively. Collectively, the physicochemical profiles of coordination
polymers 1 and 2 earmark: (a) the influence of the polycarboxylic acid nature of the ligand on the chemical
reactivity in binary and ternary systems, and (b) the critical nature of interactions in binary and ternary
discrete Cu(II)–(O,N) species emerging in aqueous media and influencing the lattice assembly of
Cu(II)–carboxylato materials of variable dimensionality (1D–3D), architecture and physicochemical
properties.
Polyhedron 01/2012; 40(1):133-144. · 2.06 Impact Factor
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ABSTRACT: Hydrothermal pH-specific reactivity in the binary/ternary systems of Pb(II) with the carboxylic acids N-hydroxyethyl-iminodiacetic acid (Heida), 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (Dpot), and 1,10-phenanthroline (Phen) afforded the new well-defined crystalline compounds [Pb(Heida)]n·nH2O(1), [Pb(Phen)(Heida)]·4H2O(2), and [Pb3(NO3)(Dpot)]n(3). All compounds were characterized by elemental analysis, FT-IR, solution or/and solid-state NMR, and single-crystal X-ray diffraction. The structures in 1–2 reveal the presence of a Pb(II) center coordinated to one Heida ligand, with 1 exhibiting a two-dimensional (2D) lattice extending to a three-dimensional (3D) one through H-bonding interactions. The concurrent aqueous speciation study of the binary Pb(II)–Heida system projects species complementing the synthetic efforts, thereby lending credence to a global structural speciation strategy in investigating binary/ternary Pb(II)-Heida/Phen systems. The involvement of Phen in 2 projects the significance of nature and reactivity potential of N-aromatic chelators, disrupting the binary lattice in 1 and influencing the nature of the ultimately arising ternary 3D lattice. 3 is a ternary coordination polymer, where Pb(II)-Dpot coordination leads to a 2D metal–organic-framework material with unique architecture. The collective physicochemical properties of 1–3 formulate the salient features of variable dimensionality metal–organic-framework lattices in binary/ternary Pb(II)-(hydroxy-carboxylate) structures, based on which new Pb(II) materials with distinct architecture and spectroscopic signature can be rationally designed and pursued synthetically.
Inorganic Chemistry 01/2012; 51(17):9282-9296. · 4.60 Impact Factor
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ABSTRACT: Diverse vanadium biological activities entail complex interactions with physiological target ligands in aqueous media and constitute the crux of the undertaken investigation at the synthetic level. Facile aqueous redox reactions, as well as nonredox reactions, of V(III) and V(V) with physiological citric acid and hydrogen peroxide, under pH-specific conditions, led to the synthesis and isolation of a well-formed crystalline material upon the addition of ethanol as the precipitating solvent. Elemental analysis pointed to the molecular formulation (NH4)4[(VO2){VO(O2)}(C6H5O7)2]·1.5H2O (1). Complex 1 was further characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectroscopy, cyclic voltammetry, and X-ray crystallography. The crystallographic structure of 1 reveals the presence of the first dinuclear V(V)-citrate complex with non-peroxo- and peroxo-containing V(V) ions, concurrently present within the basic VV2O2 core. The nonperoxo unit VO2+ and the peroxo unit VO(O2)+ are each coordinated to a triply deprotonated citrate ligand in a distinct coordination mode and coordination geometry around the V(V) ions. These units are similar to those in homodinuclear complexes bearing oxo or peroxo groups. The unique assembly of both units in the anion of 1 renders the latter as a potential intermediate in the peroxidation process, from [V2O4(C6H5O7)2]4– to [V2O2(O2)2(C6H6O7)2]2–. The transformation reactions of 1 establish its connection with several V(V) and V(IV) dinuclear species present in the aqueous distribution of the V(IV,V)-citrate systems. The shown position of 1 as an intermediate in the mechanism of H2O2 addition to dinuclear V(V)-citrate species portends its role in the complex aqueous distribution of species in the ternary V(V)-peroxo-citrate system and its potential reactivity in (bio)chemically relevant media.
Inorganic Chemistry 11/2011; 50(22):11423-36. · 4.60 Impact Factor
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ABSTRACT: The linear trinuclear Cu(II) complexes [Cu(3)(L(1))(4)(H(2)tea)(2)] (1), [Cu(3)(L(2))(4)(H(2)tea)(2)]·2CH(3)CN (2), [Cu(3)(L(2))(4)(H(2)tea)(2)] (3), [Cu(3)(L(1))(2)(H(2)tea)(2)(NO(3))(2)] (4) and the dinuclear complex [Cu(2)(L(1))(2)(H(2)tea)(2)] (5), where L(1) = 2-thiophene carboxylate, L(2) = 2-(thiophen-2-yl)-acetate and H(2)tea = the single deprotonated form of triethanolamine have been prepared and characterised while the crystal structures of 1-4 have been determined. The variable-temperature magnetic susceptibilities of complexes 1-5 have been measured in the range 2-300 K under various external fields in the range 0.02-1.0 T. X-band EPR spectra of 1-5 compounds were recorded at 4-100 K. Complexes 1, 2 and 3 found to have the same J = 33 cm(-1) and g values 2.16(1), 2.20(1) and 2.16(1) respectively while for 5 J = 15 cm(-1) and g = 2.06(1) revealing a clear ferromagnetic exchange between Cu(II) ions. Complex 4 was found to be antiferromagnetic with J = -28 cm(-1) and g = 2.21(1). The polycrystalline powder X-band EPR spectrum of complexes 1, 2, and 3 at 4 K are dominated by a transition at 1600 G (g = 4.3) which unambiguously identifies the spin of the ground multiplet (S = 3/2) while the antiferromagnetic complex 4 has a derivative centered at g = 2.1 indicative of a ground doublet (S = 1/2). Concerning complex 5 a spectrum of a dominant derivative centered at g = 2.06(1) is observed with a very weak half field transition (ca. 1500 G) indicative of the ferromagnetic nature of the system. Furthermore, for complexes 2 and 3 a strong temperature dependence of this spectroscopic g-factor is revealed and change of the g(eff) from the liquid helium temperature to the room temperature is almost 2 units.
Dalton Transactions 07/2011; 40(31):7946-56. · 3.84 Impact Factor
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ABSTRACT: The dinuclear complex [Cu(2)(L(1))(2)(H(2)tea)(2)] (1) as well as the linear trinuclear complexes [Cu(3)(L(1))(4)(H(2)tea)(2)] (2), [Cu(3)(L(2))(4)(H(2)tea)(2)] (3) and [Cu(3)(L(1))(2)(H(2)tea)(2)(NO(3))(2)] (4) where L(1) = 2-thiophene carboxylato, L(2) = 2-thiophene acetato and H(2)tea = the single deprotonated form of triethanolamine have been prepared and pharmacochemically studied. The crystal structure of 1 is also reported. In vitro antioxidant activity of free ligands and their respective copper complexes includes: a) interaction with 1,1-diphenyl-2-picrylhydrazyl stable free radical, b) the ΗΟ˙ mediated oxidation of DMSO, c) scavenging of superoxide anion radicals, d) inhibition of lipid peroxidation and e) soybean lipoxygenase inhibition. The results indicate selectivity of the complexes to different free radicals as a consequence of their physichochemical features. The majority of the complexes 1, 2, 3, 4 effectively inhibit lipid peroxidation. The trinuclear complex 3 is by far the most active with IC(50)=10 μM, within the set, followed by complexes 1 and 2. The complexes were evaluated for their efficacy as anticancer agents against different cancer and normal human cell lines. Results showed that, these compounds mediate a moderate cytotoxic response to normal and cancer cell lines tested and induce cell cycle arrest in G2/M phase of the cell cycle. Flow cytometric analysis suggested that the tested compounds can induce apoptosis.
Journal of inorganic biochemistry 06/2011; 105(6):839-49. · 3.25 Impact Factor
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ABSTRACT: Diverse vanadium biological activities entail complex interactions with physiological target ligands in aqueous media and constitute the crux of the undertaken investigation at the synthetic level. Facile aqueous redox reactions, as well as nonredox reactions, of V(III) and V(V) with physiological citric acid and hydrogen peroxide, under pH-specific conditions, led to the synthesis and isolation of a well-formed crystalline material upon the addition of ethanol as the precipitating solvent. Elemental analysis pointed to the molecular formulation (NH4)4[(VO2){VO(O2)}(C6H5O7)2]·1.5H2O (1). Complex 1 was further characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectroscopy, cyclic voltammetry, and X-ray crystallography. The crystallographic structure of 1 reveals the presence of the first dinuclear V(V)-citrate complex with non-peroxo- and peroxo-containing V(V) ions, concurrently present within the basic VV2O2 core. The nonperoxo unit VO2+ and the peroxo unit VO(O2)+ are each coordinated to a triply deprotonated citrate ligand in a distinct coordination mode and coordination geometry around the V(V) ions. These units are similar to those in homodinuclear complexes bearing oxo or peroxo groups. The unique assembly of both units in the anion of 1 renders the latter as a potential intermediate in the peroxidation process, from [V2O4(C6H5O7)2]4– to [V2O2(O2)2(C6H6O7)2]2–. The transformation reactions of 1 establish its connection with several V(V) and V(IV) dinuclear species present in the aqueous distribution of the V(IV,V)-citrate systems. The shown position of 1 as an intermediate in the mechanism of H2O2 addition to dinuclear V(V)-citrate species portends its role in the complex aqueous distribution of species in the ternary V(V)-peroxo-citrate system and its potential reactivity in (bio)chemically relevant media.
Inorganic Chemistry 01/2011; 50(22):11423-11436. · 4.60 Impact Factor
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ABSTRACT: Cobalt is an abundant metal ion present in the abiotic and biological world. The chemical reactivity of Co(II) is exemplified through complex interactions with variable molecular mass ligands, including amino acids, peptides, variable nature organic ligands, and/or phospho(nate)-derivatives thereof. Poised to gain insight into the chemical reactivity of Co(II) toward the family of mixed (carboxy)phosphonate-containing ligands, pH-specific aqueous reactions were carried out between Co(II) and N,N-bis(phosphonomethyl)-
glycine (NTA2P), leading to a new pH-structural variant species (NH4)3[Co(C4H6O8NP2)(H2O)2]�4H2O (1) at pH 8. Compound 1 was characterized analytically, spectroscopically (FT-IR, UV–Vis, EPR), and magnetically. X-ray crystallography reveals a mononuclear complex of Co(II) in an NO5 octahedral environment. The solid state magnetic and EPR data on 1 suggest the presence of a high-spin Co(II) in a distorted octahedral geometry, with a ground state of an effective spin S = 1/2. The solution UV–Vis and EPR data suggest retention of the integrity of 1, consistent with the magnetization measurements. Detailed aqueous speciation studies on binary Co(II)–carboxylate (NTA) and all Co(II)–(carboxy)phosphonate (NTAxP; x = 1–3) systems reveal the aqueous distributions of all species involved in the respective systems and project a mononuclear species not unlike that of 1 in the Co(II)–NTA2P system. The structural
and chemical attributes of the title complex reflect the (a) pH-dependent chemical reactivity in
the binary Co(II)–NTA2P system, and (b) structure–activity correlations in the aqueous media linking both high and low pH-structural variants. To this end, fundamental structural properties influence the reactivity of Co(II) toward phosphonate and mixed carboxyphosphonate ligands and are ultimately exemplified as a function of phosphonate-containing moieties in NTA derivatives. The variably configured species in such binary Co(II)–ligand systems define the pH dependence and nature of interactions between the two reagents, and could serve further as precursors in the design and discovery of new
Co(II)–organophosphonate materials of specific structural lattice, spectroscopic, and magnetic properties.
Polyhedron. 01/2011; 30(2):427-437.
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ABSTRACT: Variable-pH hydrothermal reactions of Pb(II) with dicarboxylic acids in the presence of 1,10-phenanthroline led to new solid-state compounds [Pb2(C12H8N2)4(C4H2O4)](NO3)2 (1), [Pb2(C12H8N2)4(CO3)(C4H2O4)]n 3 6nH2O (2), [Pb2(C12H8N2)(C4H2O4)2]n (3), and [Pb(C12H8N2)(C4H2O4)]n 3 2nH2O (4). All compounds were characterized by elemental
analysis, FT-IR, CP-MAS NMR, and single crystal X-ray diffraction. The collective chemical reactivity in the ternary Pb(II)-phenanthroline-dicarboxylate systems unravels seldom seen metal-assisted ligand malate/maleate to fumarate transformations, which in the presence of Pb(II) and 1,10-phenanthroline contribute to the assembly of 2D (2) and 3D lattice networks (3 and 4). All distinct assemblies in 1-4 reveal interwoven crystal lattice connections, reflecting unique physicochemical properties.
Crystal Growth & Design. 01/2011; 11(2):382-395.
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ABSTRACT: Variable-pH hydrothermal reactions of Pb(II) with dicarboxylic acids in the presence of 1,10-phenanthroline
led to new solid-state compounds [Pb2(C12H8N2)4(C4H2O4)](NO3)2 (1), [Pb2(C12H8N2)4(CO3)(C4H2O4)]n 3 6nH2O (2), [Pb2(C12H8N2)(C4H2O4)2]n (3), and [Pb(C12H8N2)(C4H2O4)]n 3 2nH2O (4). All compounds were characterized by elemental analysis, FT-IR, CP-MAS NMR, and single crystal X-ray diffraction. The collective chemical reactivity in the ternary Pb(II)-phenanthroline-dicarboxylate systems unravels seldom seen metal-assisted ligand malate/maleate to fumarate transformations, which in the presence of Pb(II) and 1,10-phenanthroline contribute to the assembly of 2D (2) and 3D lattice networks (3 and 4). All distinct assemblies in 1-4 reveal interwoven crystal lattice connections, reflecting unique physicochemical properties
Crystal Growth & Design 01/2011; 11(2):382-395. · 4.72 Impact Factor
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ABSTRACT: Cobalt is an abundant metal ion present in the abiotic and biological world. The chemical reactivity of
Co(II) is exemplified through complex interactions with variable molecular mass ligands, including amino
acids, peptides, variable nature organic ligands, and/or phospho(nate)-derivatives thereof. Poised to gain
insight into the chemical reactivity of Co(II) toward the family of mixed (carboxy)phosphonate-containing
ligands, pH-specific aqueous reactions were carried out between Co(II) and N,N-bis(phosphonomethyl)-
glycine (NTA2P), leading to a new pH-structural variant species (NH4)3[Co(C4H6O8NP2)(H2O)2]�4H2O
(1) at pH 8. Compound 1 was characterized analytically, spectroscopically (FT-IR, UV–Vis, EPR), and magnetically.
X-ray crystallography reveals a mononuclear complex of Co(II) in an NO5 octahedral environment.
The solid state magnetic and EPR data on 1 suggest the presence of a high-spin Co(II) in a
distorted octahedral geometry, with a ground state of an effective spin S = 1/2. The solution UV–Vis
and EPR data suggest retention of the integrity of 1, consistent with the magnetization measurements.
Detailed aqueous speciation studies on binary Co(II)–carboxylate (NTA) and all Co(II)–(carboxy)phosphonate
(NTAxP; x = 1–3) systems reveal the aqueous distributions of all species involved in the respective
systems and project a mononuclear species not unlike that of 1 in the Co(II)–NTA2P system. The structural
and chemical attributes of the title complex reflect the (a) pH-dependent chemical reactivity in
the binary Co(II)–NTA2P system, and (b) structure–activity correlations in the aqueous media linking
both high and low pH-structural variants. To this end, fundamental structural properties influence the
reactivity of Co(II) toward phosphonate and mixed carboxyphosphonate ligands and are ultimately
exemplified as a function of phosphonate-containing moieties in NTA derivatives. The variably configured
species in such binary Co(II)–ligand systems define the pH dependence and nature of interactions
between the two reagents, and could serve further as precursors in the design and discovery of new
Co(II)–organophosphonate materials of specific structural lattice, spectroscopic, and magnetic properties.
Polyhedron 01/2011; 30(2):427-437. · 2.06 Impact Factor
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ABSTRACT: Co(II) and Zn(II) ions exhibit variable reactivity toward O-containing ligands in aqueous media, affording isolable materials with distinct solid-state lattice properties. d-(-)-quinic acid is a cellular α-hydroxycarboxylate metal ion binder, which reacts with Co(II) and Zn(II) under pH-specific hydrothermal conditions, leading to the isolation of two new species [Co(2)(C(7)H(11)O(6))(4)](n)·nH(2)O (1) and [Zn(3)(C(7)H(11)O(6))(6)](n)·nH(2)O (2). Compound 1 was characterized by elemental analysis, spectroscopic techniques (FT-IR, UV-visible, EPR), magnetic studies, and X-ray crystallography. Compound 2 was characterized by elemental analysis, spectroscopic techniques (FT-IR, ESI-MS), and X-ray crystallography. The 2D molecular lattices in 1 and 2 reveal the presence of octahedral M(II) units bound exclusively to quinate in a distinct fashion, thereby projecting a unique chemical reactivity in each investigated system. The magnetic susceptibility and solid-state/frozen solution EPR data on 1 support the presence of a high-spin octahedral Co(II) in an oxygen environment, having a ground state with an effective spin of S = 1/2. Concurrent aqueous speciation studies on the binary Zn(II)-quinate system unravel the nature and properties of species arising from Zn(II)-quinate interactions as a function of pH and molar ratio. The physicochemical profiles of 1 and 2, in the solid state and in solution, earmark the importance of (a) select synthetic hydrothermal reactivity conditions, affording new well-defined lattice dimensionality and nuclearity M(II)-quinate materials, (b) structural speciation approaches delineating solid state-aqueous solution correlations in the binary M(II)-quinate systems, and (c) pH-specific chemical reactivity in binary M(II)-quinate systems reflecting structurally unique associations of simple aqueous complexes into distinctly assembled 2D crystalline lattices.
Inorganic Chemistry 11/2010; 49(24):11449-62. · 4.60 Impact Factor
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ABSTRACT: Co(II) and Zn(II) ions exhibit variable reactivity toward O-containing ligands in aqueous media, affording isolable materials with distinct solid-state lattice properties. D-(-)-quinic acid is a cellular R-hydroxycarboxylate metal ion binder, which reacts with Co(II) and Zn(II) under pH-specific hydrothermal conditions, leading to the isolation of
two new species [Co2(C7H11O6)4]n 3 nH2O (1) and [Zn3(C7H11O6)6]n 3 nH2O (2). Compound 1 was characterized by elemental analysis, spectroscopic techniques (FT-IR, UV-visible, EPR), magnetic studies, and X-ray crystallography.
Compound 2 was characterized by elemental analysis, spectroscopic techniques (FT-IR, ESI-MS), and X-ray crystallography. The 2D molecular lattices in 1 and 2 reveal the presence of octahedral M(II) units bound exclusively to quinate in a distinct fashion, thereby projecting a unique chemical reactivity in each investigated system. The magnetic susceptibility and solid-state/frozen solution EPR data on 1 support the presence of a high-spin octahedral Co(II) in an oxygen environment, having a ground state with an effective spin of S = 1/2. Concurrent aqueous speciation studies on the binary Zn(II)-quinate system unravel the nature and properties of species arising from Zn(II)-quinate interactions as a function of pH and molar ratio. The physicochemical profiles of 1 and 2, in the solid state and in solution, earmark the importance of (a) select synthetic hydrothermal reactivity conditions, affording new well-defined lattice dimensionality and nuclearity M(II)-quinate materials, (b) structural speciation approaches delineating solid state-aqueous solution correlations in the binary M(II)-quinate systems, and (c) pH-specific chemical reactivity in binary M(II)-quinate systems reflecting structurally unique associations of simple aqueous complexes into distinctly
assembled 2D crystalline lattices.
Inorganic Chemistry. 01/2010; 49 (24):11449–11462.
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ABSTRACT: Co(II) and Zn(II) ions exhibit variable reactivity toward O-containing ligands in aqueous media, affording isolable materials with distinct solid-state lattice properties. D-(-)-quinic acid is a cellular R-hydroxycarboxylate metal ion binder, which reacts with Co(II) and Zn(II) under pH-specific hydrothermal conditions, leading to the isolation of two new species [Co2(C7H11O6)4]n 3 nH2O (1) and [Zn3(C7H11O6)6]n 3 nH2O (2). Compound 1 was characterized by elemental analysis, spectroscopic techniques (FT-IR, UV-visible, EPR), magnetic studies, and X-ray crystallography. Compound 2 was characterized by elemental analysis, spectroscopic techniques (FT-IR, ESI-MS), and X-ray
crystallography. The 2D molecular lattices in 1 and 2 reveal the presence of octahedral M(II) units bound exclusively to quinate in a distinct fashion, thereby projecting a unique chemical reactivity in each investigated system. The magnetic susceptibility and solid-state/frozen solution EPR data on 1 support the presence of a high-spin octahedral Co(II) in an oxygen environment, having a ground state with an effective spin of S = 1/2. Concurrent aqueous speciation studies on the binary Zn(II)-quinate system unravel the nature and properties of species arising from Zn(II)-quinate interactions as a function of pH and molar ratio. The physicochemical profiles of 1 and 2, in the solid state and in solution, earmark the importance of (a) select synthetic hydrothermal reactivity conditions, affording new well-defined lattice dimensionality and nuclearity M(II)-quinate materials, (b) structural speciation approaches delineating solid state-aqueous solution correlations in the binary M(II)-quinate systems, and (c) pH-specific chemical reactivity in
binary M(II)-quinate systems reflecting structurally unique associations of simple aqueous complexes into distinctly assembled 2D crystalline lattices
Inorganic Chemistry 01/2010; 49(24):11449-11462. · 4.60 Impact Factor
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ABSTRACT: Efforts to delineate the interactions of neurotoxic Al(III) with low molecular mass substrates relevant to neurodegenerative processes, led to the investigation of the pH-specific synthetic chemistry of the binary Al(III)-[N-(phosphonomethyl) iminodiacetic acid] (Al-NTAP), Al(III)-[nitrilo-tris(methylene-phosphonic acid)] (Al-NTA3P), and Al(III)-[1-hydroxy ethylidene-1,1-diphosphonic acid] (Al-HEDP) systems, in correlation with solution speciation studies. Reaction of Al(NO(3))(3).9H(2)O with NTAP at pH 7.0 and 4.0 afforded the new species (CH(6)N(3))(4)[Al(2)(C(5)H(6)NPO(7))(2)(OH)(2)].8H(2)O (1) and (NH(4))(2)[Al(2)(C(5)H(6)NPO(7))(2)(H(2)O)(2)].4H(2)O (2), while reaction of Al(NO(3))(3).9H(2)O with NTA3P led to K(8)[Al(2)(C(3)H(6)NP(3)O(9))(2)(OH)(2)].20H(2)O (3). Complexes 1-3 were characterized by elemental analysis, FT-IR, (13)C, (31)P, (1)H NMR (for 1-2 solid state and solution NMR where feasible), and X-ray crystallography. The structures of 1-3 reveal the presence of uniquely defined dinuclear complexes of octahedral Al(III) bound to fully deprotonated phosphonate ligands, water and hydroxo moieties. The aqueous solution speciation studies on the aforementioned binary systems project a clear picture of the binary Al(III)-(carboxy)phosphonate interactions and species under variable pH-conditions and specific Al(III):ligand stoichiometry. The concurrent solid state and solution work (a) exemplifies essential structural and chemical attributes of soluble aqueous species, reflecting well-defined interactions of Al(III) with phosphosubstrates and (b) strengthens the potential linkage of neurotoxic Al(III) chemical reactivity toward O,N-containing (carboxy)phosphate-rich cellular targets.
Journal of inorganic biochemistry 08/2009; 103(11):1530-41. · 3.25 Impact Factor
