Synthesis, Characterization, and Spectroscopic Investigation of New Iron(III) and Copper(II) Complexes of a Carboxylate Rich Ligand and Their Interaction with Carbohydrates in Aqueous Solution

New tetra-iron­(III) (K₄[<b>1</b>]·25H₂O·(CH₃)₂CO and K₃[<b>2</b>]·3H₂O·(OH)) and di-copper­(II) (Na₃[<b>3</b>]·5H₂O) complexes as carbohydrate binding models have been synthesized and fully characterized used several techniques including single crystal X-ray crystallography. Whereas K₄[<b>1</b>]·25H₂O·(CH₃)₂CO and Na₃[<b>3</b>]·5H₂O are completely water-soluble, K₃[<b>2</b>]·3H₂O·(OH) is less soluble in all common solvents including water. The binding of substrates, such as d-mannose, d-glucose, d-xylose, and xylitol with the water-soluble complexes in different reaction conditions were investigated. In aqueous alkaline media, complexes K₄[<b>1</b>]·25H₂O·(CH₃)₂CO and Na₃[<b>3</b>]·5H₂O showed coordination ability toward the applied substrates. Even in the presence of stoichiometric excess of the substrates, the complexes form only 1:1 (complex/substrate) molar ratio species in solution. Apparent binding constants, p<i>K</i>_app, values between the complexes and the substrates were determined and specific mode of substrate binding is proposed. The p<i>K</i>_app values showed that d-mannose coordinates strongest to K₄[<b>1</b>]·25H₂O·(CH₃)₂CO and Na₃[<b>3</b>]·5H₂O. Syntheses, characterizations and detailed substrate binding study using spectroscopic techniques and single crystal X-ray diffraction are reported

New Dinuclear Cobalt(II) and Zinc(II) Complexes of a Carboxylate-Rich Dinucleating Ligand: Synthesis, Structure, Spectroscopic Characterization, and Their Interactions with Sugars

Sugar–metal ion interactions in aqueous medium are involved in many biochemical processes such as the transport and storage of metals, the function and regulation of sugar-metabolizing metalloenzymes, the mechanism of action of metal-containing pharmaceuticals, and toxic metal metabolism. To understand such interactions we synthesized and fully characterized two new dinuclear cobalt­(II) and zinc­(II) complexes as carbohydrate binding models for xylose/glucose isomerases (XGI). Synthesis of the dicobalt complex, Na₃[Co₂(ccdp)­(μ-HCO₂)]­BF₄·9H₂O·2CH₃OH (<b>1</b>), was performed in methanol with stoichiometric amounts of Co­(BF₄)₂·6H₂O and the dinucleating ligand, H₅ccdp (H₅ccdp <i>= N,N′</i>-bis­[2-carboxybenzomethyl]-<i>N,N′</i>-bis­[carboxymethyl]-1,3-diaminopropan-2-ol), in the presence of NaOH at ambient temperature in an argon glovebox. Similarly, the dizinc complex, [NMe₄]₂[Zn₂(ccdp)­(μ-OAc)]·CH₃OH (<b>2</b>), was synthesized from Zn­(OAc)₂·2H₂O and H₅ccdp in the presence of NMe₄OH at ambient temperature in methanol. Binding of the complexes with carbohydrates was investigated under different reaction conditions. In aqueous alkaline media, complexes <b>1</b> and <b>2</b> showed chelating ability towards the biologically important sugars, d-glucose and d-xylose, and a polyalcohol enzyme inhibitor (xylitol). In solution, each complex forms a 1:1 complex-substrate bound product with specific binding constant values. Synthesis, characterization details, and substrate binding using spectroscopic techniques and single-crystal X-ray diffraction are reported

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

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