Linking PO43- and HAsO42- anions with a dinuclear Zn-2(II)] complex: Formation and stabilization of novel decanuclear metallomacrocyclic Zn-10(II)] and tetranuclear Zn-4(II)] clusters

The linkage of PO43- and HAsO42--anions with a newly synthesized five-coordinate dinuclear zinc complex, Zn-2(cpdp)(H2O)(2)]Cl (1) H(3)cpdp =N,N'-bis2-carboxybenzomethyl]-N,N'-bis2-pyridylmethyl]-1,3diamino propan-2-ol], has been explored. In methanol-water, the reaction of 1 with Na2HPO4 center dot 2H(2)O and Na2HAsO4 center dot 7H(2)O/NaBr separately, at ambient temperature, yielded the novel phosphate-bridged decanuclear zinc cluster, (H3O)(4)Zn-10(cPdP)(4)(mu(5)-PO4)(2)(H2O)(6)](6 center dot Cl)center dot 53H(2)O (2) and hydrogen arsenate bridged tetranuclear zinc cluster, Na-2Zn-4(cpdp)(2)(mu(4)-HAsO4)]ClBr center dot 13H(2)O (3), respectively. Analysis of the single crystal X-ray structure discloses that the metallic core of cluster 2 entails eight distorted trigonal bipyramidal and two distorted octahedral zinc ions, displaying a mu(5):eta(2):eta(1):eta(1):eta 1 bridging mode of two POi-groups. The metallic core of cluster 3 holds four distorted trigonal bipyramidal zinc ions, showing a mu(4):eta(1):eta(1):eta(1):eta 1 bridging mode of the HAsO42- group. In solution, UV-Vis titration spectra of complex 1 upon increasing the concentration of the PO43- and HAsO(4)(2-)anions show a significant binding-induced increase in the absorption intensities of 1, accompanied by a substantial red shift. Additionally, the integrity of all three zinc assemblies has been confirmed by H-1 and C-13 NMR spectroscopic data in solution. The thermal behaviors of 1, 2 and 3 have been studied by thermogravimetric analysis (TGA). (C) 2016 Elsevier Ltd. All rights reserved

Formation of out of plane oxime metallacycles in [Cu(2)] and [Cu(4)] complexes

The reaction Of Cu(ClO(4))(2)center dot 6H(2)O with dimethylglyoxime (H(2)dmg) in a 1:1 mole ratio in aqueous methanol at room temperature affords the dinuclear complex [Cu(2)(mu-Hdmg)(4)] (1). Reaction of 1 with [Cu(bpy)(H(2)O)(2)](ClO(4))(2) (bpy = 2,2`-bipyridine) in a 1:1 mole ratio in aqueous methanol at room temperature yields the tetranuclear complex [Cu(2)(mu-HdMg)(2)(mu-dMg)(2)(bpy)(2)(H(2)O)(2)](ClO(4))(2) (2). The direct reaction of Cu(ClO(4))(2)center dot 6H(2)O with H(2)dmg and bpy in a 2:21 mole ratio in aqueous methanol at room temperature also yields 2 quantitatively. The complexes 1 and 2 were structurally characterized by X-ray crystallography. Unlike the binding in Ni/Co-dmg, two different types of N-O bridging modes during the oxime based metallacycle formation and stacking of square planar units have been identified in these complexes. The neutral dinuclear complex 1 has CuN(4)O coordination spheres and complex 2 consists of a dicationic [Cu(2)(mu-HdMg)(2)(mu-dMg)(2)(bpy)(2)(H(2)O)(2)](2+) unit and two uncoordinated ClO(4)(-) anions having CuN(4)O and CuN(2)O(3) coordination spheres. The two copper(II) ions are at a distance of 3.846(8) angstrom in 1 for the trans out of plane link and at 3.419(10) and 3.684(10) angstrom in 2 for the trans out of plane and cis in plane arrangements, respectively. The average Cu-N(oxime) distances are 1.953 and 1.935 angstrom, respectively. The average basal and apical Cu-N(oxime) distances are 1.945, 2.295 and 2.429 angstrom. The UV-Vis spectra of 2 is similar to the spectrum of the reaction mixture of 1 and [Cu(bpy)(H(2)O)(2)](2+). Variable temperature magnetic properties measurement shows that the interaction between the paramagnetic copper centers in complex I is antiferromagnetic in nature. The EPR spectra of frozen solution of the complexes at 77 K consist of axially symmetric fine-structure transitions (Delta M(S) = 1) and half-field signals (Delta M(S) = 2) at ca. 1600 G, suggesting the presence of appreciable Cu-Cu interactions. (C) 2009 Elsevier Ltd. All rights reserved.DST, New Delh

New symmetrical dinucleating ligand based assembly of bridged dicopper(II) and dizinc(II) centers: Synthesis, structure, spectroscopy, magnetic properties and glycoside hydrolysis

Two dinuclear copper(II) complexes Li(H2O)(3)(CH3OH)](4)Cu2Br4]Cu-2(cpdp)(mu-O2CCH3)](4)(OH)(2) (1), Cu (H2O)(4)]Cu-2(cpdp)(mu-O2CC6H5)](2)Cl-2 center dot 5H(2)O (2), and a dinuclear zinc(II) complex Zn-2(cpdp)(mu-O2CCH3)] (3) have been synthesized using pyridine and benzoate functionality based new symmetrical dinucleating ligand, N, N'-Bis2-carboxybenzomethyl]-N, N'-Bis2-pyridylmethyl]-1,3-diaminopropan-2-ol (H(3)cpdp). Complexes 1, 2 and 3 have been synthesized by carrying out reaction of the ligand H3cpdp with stoichiometric amounts of Cu-2(O2CCH3)(4)(H2O)(2)], CuCl2 center dot 2H(2)O/C6H5COONa, and Zn(CH3COO)(2)center dot 2H(2)O, respectively, in methanol in the presence of NaOH at ambient temperature. Characterizations of the complexes have been done using various analytical techniques including single crystal X-ray structure determination. The X-ray crystal structure analyses reveal that the copper(II) ions in complexes 1 and 2 are in a distorted square pyramidal geometry with Cu-Cu separation of 3.455(8) angstrom and 3.492(1)angstrom, respectively. The DFT optimized structure of complex 3 indicates that two zinc(II) ions are in a distorted square pyramidal geometry with Zn-Zn separation of 3.492(8)angstrom. UV-Vis and mass spectrometric analyses of the complexes confirm their dimeric nature in solution. Furthermore, H-1 and C-13 NMR spectroscopic investigations authenticate the integrity of complex 3 in solution. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interactions between the copper centers, with J = -26.0 cm(-1) and -23.9 cm(-1) ((H) over cap = -2JS(1)S(2)) in complexes 1 and 2, respectively. In addition, glycosidase-like activity of the complexes has been investigated in aqueous solution at pH similar to 10.5 by UV-Vis spectrophotometric technique using p-nitrophenyl-alpha-D-glucopyranoside (4) and p-nitrophenyl-beta-D-glucopyranoside (5) as model substrates. (C) 2015 Elsevier B.V. All rights reserved

Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and Thermal Studies

Three, PO₄^3–/HPO₄^2– and AsO₄^3–-incorporated, new tetranuclear complexes of copper­(II) and zinc­(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H₃cpdp (H₃cpdp = <i>N</i>,<i>N</i>′-Bis­[2-carboxybenzomethyl]-<i>N</i>,<i>N</i>′-Bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper­(II) chloride in the presence of either NaOH/Na₂HPO₄·2H₂O or KOH/Na₂HAsO₄·7H₂O lead to the isolation of the tetranuclear complexes Na₃[Cu₄(cpdp)₂(μ₄-PO₄)]­(OH)₂·14H₂O (<b>1</b>) and K₂[Cu₄(cpdp)₂(μ₄-AsO₄)]­(OH)·16²/₃H₂O (<b>2</b>), respectively. Similarly, the reaction of H₃cpdp with zinc­(II) chloride in the presence of NaOH/Na₂HPO₄·2H₂O yields a tetranuclear complex, Na­(H₃O)₂[Zn₄(cpdp)₂(μ₄-HPO₄)]­Cl₃·12¹/₂H₂O (<b>3</b>). All complexes are characterized by single-crystal X-ray diffraction and other analytical techniques, such as Fourier transform infrared and UV−vis spectroscopy, thermogravimetric and electrochemical studies. The solid-state molecular framework of each complex contains two monocationic [M₂(cpdp)]⁺ (M = Cu, Zn) units, which are exclusively coordinated to either phosphate/hydrogen phosphate or arsenate groups in a unique mode. All three complexes exhibit a μ₄:η¹:η¹:η¹:η¹ bridging mode of the PO₄^3–/HPO₄^2–/AsO₄^3– groups, with each bridging among four metal ions. The thermal properties of all three complexes have been investigated by thermogravimetric analysis. Low-temperature magnetic studies of complexes <b>1</b> and <b>2</b> disclose moderate antiferromagnetic interactions mediated among the copper centers through alkoxide and phosphate/arsenate bridges. Electrochemical studies of complexes <b>1</b> and <b>2</b> in dimethylformamide using cyclic voltammetry reveal the presence of a fairly assessable one-electron metal-based irreversible reduction and one quasireversible oxidation couple

Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and Thermal Studies

Three, PO₄^3–/HPO₄^2– and AsO₄^3–-incorporated, new tetranuclear complexes of copper­(II) and zinc­(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H₃cpdp (H₃cpdp = <i>N</i>,<i>N</i>′-Bis­[2-carboxybenzomethyl]-<i>N</i>,<i>N</i>′-Bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper­(II) chloride in the presence of either NaOH/Na₂HPO₄·2H₂O or KOH/Na₂HAsO₄·7H₂O lead to the isolation of the tetranuclear complexes Na₃[Cu₄(cpdp)₂(μ₄-PO₄)]­(OH)₂·14H₂O (<b>1</b>) and K₂[Cu₄(cpdp)₂(μ₄-AsO₄)]­(OH)·16²/₃H₂O (<b>2</b>), respectively. Similarly, the reaction of H₃cpdp with zinc­(II) chloride in the presence of NaOH/Na₂HPO₄·2H₂O yields a tetranuclear complex, Na­(H₃O)₂[Zn₄(cpdp)₂(μ₄-HPO₄)]­Cl₃·12¹/₂H₂O (<b>3</b>). All complexes are characterized by single-crystal X-ray diffraction and other analytical techniques, such as Fourier transform infrared and UV−vis spectroscopy, thermogravimetric and electrochemical studies. The solid-state molecular framework of each complex contains two monocationic [M₂(cpdp)]⁺ (M = Cu, Zn) units, which are exclusively coordinated to either phosphate/hydrogen phosphate or arsenate groups in a unique mode. All three complexes exhibit a μ₄:η¹:η¹:η¹:η¹ bridging mode of the PO₄^3–/HPO₄^2–/AsO₄^3– groups, with each bridging among four metal ions. The thermal properties of all three complexes have been investigated by thermogravimetric analysis. Low-temperature magnetic studies of complexes <b>1</b> and <b>2</b> disclose moderate antiferromagnetic interactions mediated among the copper centers through alkoxide and phosphate/arsenate bridges. Electrochemical studies of complexes <b>1</b> and <b>2</b> in dimethylformamide using cyclic voltammetry reveal the presence of a fairly assessable one-electron metal-based irreversible reduction and one quasireversible oxidation couple

Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and Thermal Studies

Three, PO₄^3–/HPO₄^2– and AsO₄^3–-incorporated, new tetranuclear complexes of copper­(II) and zinc­(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H₃cpdp (H₃cpdp = <i>N</i>,<i>N</i>′-Bis­[2-carboxybenzomethyl]-<i>N</i>,<i>N</i>′-Bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper­(II) chloride in the presence of either NaOH/Na₂HPO₄·2H₂O or KOH/Na₂HAsO₄·7H₂O lead to the isolation of the tetranuclear complexes Na₃[Cu₄(cpdp)₂(μ₄-PO₄)]­(OH)₂·14H₂O (<b>1</b>) and K₂[Cu₄(cpdp)₂(μ₄-AsO₄)]­(OH)·16²/₃H₂O (<b>2</b>), respectively. Similarly, the reaction of H₃cpdp with zinc­(II) chloride in the presence of NaOH/Na₂HPO₄·2H₂O yields a tetranuclear complex, Na­(H₃O)₂[Zn₄(cpdp)₂(μ₄-HPO₄)]­Cl₃·12¹/₂H₂O (<b>3</b>). All complexes are characterized by single-crystal X-ray diffraction and other analytical techniques, such as Fourier transform infrared and UV−vis spectroscopy, thermogravimetric and electrochemical studies. The solid-state molecular framework of each complex contains two monocationic [M₂(cpdp)]⁺ (M = Cu, Zn) units, which are exclusively coordinated to either phosphate/hydrogen phosphate or arsenate groups in a unique mode. All three complexes exhibit a μ₄:η¹:η¹:η¹:η¹ bridging mode of the PO₄^3–/HPO₄^2–/AsO₄^3– groups, with each bridging among four metal ions. The thermal properties of all three complexes have been investigated by thermogravimetric analysis. Low-temperature magnetic studies of complexes <b>1</b> and <b>2</b> disclose moderate antiferromagnetic interactions mediated among the copper centers through alkoxide and phosphate/arsenate bridges. Electrochemical studies of complexes <b>1</b> and <b>2</b> in dimethylformamide using cyclic voltammetry reveal the presence of a fairly assessable one-electron metal-based irreversible reduction and one quasireversible oxidation couple

Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and Thermal Studies

Three, PO₄^3–/HPO₄^2– and AsO₄^3–-incorporated, new tetranuclear complexes of copper­(II) and zinc­(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H₃cpdp (H₃cpdp = <i>N</i>,<i>N</i>′-Bis­[2-carboxybenzomethyl]-<i>N</i>,<i>N</i>′-Bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper­(II) chloride in the presence of either NaOH/Na₂HPO₄·2H₂O or KOH/Na₂HAsO₄·7H₂O lead to the isolation of the tetranuclear complexes Na₃[Cu₄(cpdp)₂(μ₄-PO₄)]­(OH)₂·14H₂O (<b>1</b>) and K₂[Cu₄(cpdp)₂(μ₄-AsO₄)]­(OH)·16²/₃H₂O (<b>2</b>), respectively. Similarly, the reaction of H₃cpdp with zinc­(II) chloride in the presence of NaOH/Na₂HPO₄·2H₂O yields a tetranuclear complex, Na­(H₃O)₂[Zn₄(cpdp)₂(μ₄-HPO₄)]­Cl₃·12¹/₂H₂O (<b>3</b>). All complexes are characterized by single-crystal X-ray diffraction and other analytical techniques, such as Fourier transform infrared and UV−vis spectroscopy, thermogravimetric and electrochemical studies. The solid-state molecular framework of each complex contains two monocationic [M₂(cpdp)]⁺ (M = Cu, Zn) units, which are exclusively coordinated to either phosphate/hydrogen phosphate or arsenate groups in a unique mode. All three complexes exhibit a μ₄:η¹:η¹:η¹:η¹ bridging mode of the PO₄^3–/HPO₄^2–/AsO₄^3– groups, with each bridging among four metal ions. The thermal properties of all three complexes have been investigated by thermogravimetric analysis. Low-temperature magnetic studies of complexes <b>1</b> and <b>2</b> disclose moderate antiferromagnetic interactions mediated among the copper centers through alkoxide and phosphate/arsenate bridges. Electrochemical studies of complexes <b>1</b> and <b>2</b> in dimethylformamide using cyclic voltammetry reveal the presence of a fairly assessable one-electron metal-based irreversible reduction and one quasireversible oxidation couple

Synthesis, Structure, Spectroscopic Characterization, and Protein Binding Affinity of New Water-Soluble Hetero- and Homometallic Tetranuclear [Cu^II₂Zn^II₂] and [Cu^II₄] Clusters

Two new water-soluble hetero- and homometallic tetranuclear clusters, Na₄[Cu₂Zn₂(ccdp)₂(μ-OH)₂]·CH₃OH·6H₂O (<b>1</b>) and K₃[Cu₄(ccdp)₂(μ-OH)­(μ-OH₂)]·14H₂O (<b>2</b>), have been synthesized in methanol–water at room temperature by exploiting the flexibility, chelating ability, and bridging potential of a carboxylate-rich dinucleating ligand, <i>N</i>,<i>N</i>′-bis­(2-carboxybenzomethyl)-<i>N</i>,<i>N</i>′-bis­(carboxymethyl)-1,3 diaminopropan-2-ol (H₅ccdp). Complex <b>1</b> is obtained through the self-assembly of two monoanionic [CuZn­(ccdp)]⁻ fragments, which are, in turn, exclusively bridged by two μ-OH^– groups. Similarly, complex <b>2</b> is formed through the self-assembly of two monoanionic [Cu₂(ccdp)]⁻ species exclusively bridged by one μ-OH^– and one μ-OH₂ groups. Complexes <b>1</b> and <b>2</b> are fully characterized in the solid state as well as in solution using various analytical techniques including a single-crystal X-ray diffraction study. The X-ray crystal structure of <b>1</b> reveals that two Cu^II centers are in a distorted square-pyramidal geometry, whereas two Zn^II centers are in a distorted trigonal-bipyramidal geometry. The solid-state structure of <b>2</b> contains two dinuclear [Cu₂(ccdp)]⁻ units having one Cu^II center in a distorted square-pyramidal geometry and another Cu^II center in a distorted trigonal-bipyramidal geometry within each dinuclear unit. In the powder state, the high-field EPR spectrum of complex <b>1</b> indicates that two Cu^II ions are not spin-coupled, whereas that of complex <b>2</b> exhibits at least one noninteracting Cu^II center coordinated to a nitrogen atom of the ligand. Both complexes are investigated for their binding affinity with the protein bovine serum albumin (BSA) in an aqueous medium at pH ∼7.2 using fluorescence spectroscopy. Synchronous fluorescence spectra clearly reveal that complexes <b>1</b> and <b>2</b> bind to the active sites in the protein, indicating that the effect is more pronounced toward tyrosine than tryptophan. Density functional theory calculations have been carried to find the Fukui functions at the metal sites in complexes <b>1</b> and <b>2</b> to predict the possible metal centers involved in the binding process with BSA protein

Synthesis, Structure, Spectroscopic Characterization, and Protein Binding Affinity of New Water-Soluble Hetero- and Homometallic Tetranuclear [Cu^II₂Zn^II₂] and [Cu^II₄] Clusters

Two new water-soluble hetero- and homometallic tetranuclear clusters, Na₄[Cu₂Zn₂(ccdp)₂(μ-OH)₂]·CH₃OH·6H₂O (<b>1</b>) and K₃[Cu₄(ccdp)₂(μ-OH)­(μ-OH₂)]·14H₂O (<b>2</b>), have been synthesized in methanol–water at room temperature by exploiting the flexibility, chelating ability, and bridging potential of a carboxylate-rich dinucleating ligand, <i>N</i>,<i>N</i>′-bis­(2-carboxybenzomethyl)-<i>N</i>,<i>N</i>′-bis­(carboxymethyl)-1,3 diaminopropan-2-ol (H₅ccdp). Complex <b>1</b> is obtained through the self-assembly of two monoanionic [CuZn­(ccdp)]⁻ fragments, which are, in turn, exclusively bridged by two μ-OH^– groups. Similarly, complex <b>2</b> is formed through the self-assembly of two monoanionic [Cu₂(ccdp)]⁻ species exclusively bridged by one μ-OH^– and one μ-OH₂ groups. Complexes <b>1</b> and <b>2</b> are fully characterized in the solid state as well as in solution using various analytical techniques including a single-crystal X-ray diffraction study. The X-ray crystal structure of <b>1</b> reveals that two Cu^II centers are in a distorted square-pyramidal geometry, whereas two Zn^II centers are in a distorted trigonal-bipyramidal geometry. The solid-state structure of <b>2</b> contains two dinuclear [Cu₂(ccdp)]⁻ units having one Cu^II center in a distorted square-pyramidal geometry and another Cu^II center in a distorted trigonal-bipyramidal geometry within each dinuclear unit. In the powder state, the high-field EPR spectrum of complex <b>1</b> indicates that two Cu^II ions are not spin-coupled, whereas that of complex <b>2</b> exhibits at least one noninteracting Cu^II center coordinated to a nitrogen atom of the ligand. Both complexes are investigated for their binding affinity with the protein bovine serum albumin (BSA) in an aqueous medium at pH ∼7.2 using fluorescence spectroscopy. Synchronous fluorescence spectra clearly reveal that complexes <b>1</b> and <b>2</b> bind to the active sites in the protein, indicating that the effect is more pronounced toward tyrosine than tryptophan. Density functional theory calculations have been carried to find the Fukui functions at the metal sites in complexes <b>1</b> and <b>2</b> to predict the possible metal centers involved in the binding process with BSA protein