Bita Shafaatian

New platinum(IV) complexes containing N2S2 donor atoms were synthesized by the reactions of [Pt(p-MeC6H4)2(SMe2)2] and [PtCl2(DMSO)2] with 2,2′-dithiopyridine (dtp) in 1:1 M ratio. In these reactions, 2-mercaptopyridine (mpy) ligands were formed through the cleavage of the disulfide bond in 2,2′-dithiopyridine. The mpy ligands were coordinated to the platinum center via the nitrogen and sulfur atoms and the obtained platinum(IV) complexes exhibited octahedral geometry. The complexes were characterized by FT-IR, 1H NMR, UV–Vis, elemental analyses and conductometry. The crystal structure of the arylplatinum(IV) complex containing C2N2S2 donor atoms was determined by single crystal X-ray diffraction. The obtained molar conductance values revealed that the platinum(IV) complexes were nonelectrolytes. The interactions of the complexes with calf thymus DNA (CT-DNA) were investigated by absorption and fluorescence spectroscopy, cyclic voltammetry and viscometry methods. The intrinsic binding constants (Kb) of the complexes with CT-DNA, obtained from UV–Vis absorption data, were 9.60 × 104 M−1 and 11.56 × 104 M−1. Furthermore, the enthalpy and entropy of the interaction between the platinum(IV) complexes and CT-DNA were calculated. The obtained data revealed positive enthalpy and entropy changes indicating a hydrophobic interaction between these complexes and CT-DNA. © 2018 Elsevier B.V.

New complexes of arylplatinum(II) and arylplatinum(IV) containing a bridging ligand, 4,4′-bipyridine, were synthesized by the reaction of starting material of platinum(II) including para-tolyl groups,[(p-MeC6H4)2Pt(SMe2)2], with the 4,4′-bipyridine ligand in 1:1 molar stoichiometry. In the synthesized complexes, the ligand was bonded to the platinum center through the nitrogen donor atoms. To investigate the kinetic reaction of the platinum(II) complex with iodomethane (CH3-I) as a reagent, the oxidative addition reaction of this reagent with Pt(II) was performed in dichloromethane and a Pt(IV) complex with the octahedral geometry was formed. The synthesized complexes have been characterized by different spectroscopic methods such as FT-IR, 1H NMR, UV–vis, and elemental analysis. Moreover, the conductivity measurements showed nonelectrolyte characteristics for these complexes. The obtained data showed that the complexes have 1:1 metal-to-ligand molar ratio. Also, the oxidative addition reaction of CH3I with the arylplatinum(II) complex at different temperatures was used for obtaining kinetic parameters such as rate constants, activation energy, entropy, and enthalpy of activation using the Microsoft Excel solver. From the acquired data, an SN2 mechanism was suggested for the oxidative addition reaction. © 2018 Wiley Periodicals, Inc.

New complexes of nickel(II) and palladium(II) were synthesized using the ferrocenyl imine ligand, which was formed by the condensation of 2-aminothiophenol and acetylferrocene. This bidentate Schiff base ligand was coordinated to the metal ions through the NS donor atoms. Monomeric complexes of nickel(II) and palladium(II) were synthesized by the reactions of the Schiff base ligand with nickel(II) and palladium(II) chloride in a 2:1 M ratio. In these complexes, the thiol group was deprotonated and coordinated to the metals. The molar conductivity values of the complexes in DMSO showed the presence of non-electrolyte species. The fluorescence characteristics of the Schiff base ligand and its complexes were studied in DMSO. The synthesized complexes were characterized by FT-IR, 1H NMR, UV–vis spectroscopy, elemental analysis, and conductometry. Furthermore, the binding interactions of the complexes with DNA were investigated by electronic absorption spectroscopy, and the intrinsic binding constant (Kb) was calculated. Moreover, viscosity and melting temperature (Tm) were investigated in order to further explore the nature of interactions between the complexes and DNA. © 2017 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

New Schiff base complexes of zinc(II), copper(II), nickel(II), and vanadium(IV) were synthesized using the Schiff base ligand formed by the condensation of 2-aminoethanethiol and 2-hydroxy-1-naphthaldehyde. The tetradentate Schiff base ligandN,N-(3,4-dithiahexane-1,6-diyl)bis(2-hydroxy-1-naphthaleneimine), containing a disulfide bond, was coordinated to the metal(II) ions through the two azomethine nitrogen atoms and two deprotonated phenolic oxygens of two different ligands which was connected to each other by sulfur-sulfur bond. The molar conductivity values of complexes in DMSO solvent implied the presence of nonelectrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were studied in dimethylsulfoxide. The Schiff base ligand and its complexes were characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of tetradentate Schiff base ligand was characterized by single crystal X-ray diffraction. The Schiff base ligand was contained disulfide bond. Furthermore, the binding interaction of these complexes with calf thymus DNA (CT-DNA) was investigated by different methods. © 2017, Taylor and Francis Group, LLC

New dimer complexes of zinc(II), copper(II) and nickel(II) were synthesized using the Schiff base ligand which was formed by the condensation of 2-aminothiophenol and 2-hydroxy-5-methyl benzaldehyde. This tridentate Schiff base ligand was coordinated to the metal ions through the NSO donor atoms. In order to prevent the oxidation of the thiole group during the formation of Schiff base and its complexes, all of the reactions were carried out under an inert atmosphere of argon. The X-ray structure of the Schiff base ligand showed that in the crystalline form the SH groups were oxidized to produce a disulfide Schiff base as a new double Schiff base ligand. The molar conductivity values of the complexes in dichloromethane implied the presence of non-electrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were also studied in dichloromethane. The products were characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of the double Schiff base was determined by single crystal X-ray diffraction. Furthermore, the density functional theory (DFT) calculations were performed at the B3LYP/6-31G(d,p) level of theory for the determination of the optimized structures of Schiff base complexes. © 2016 Elsevier B.V. All rights reserved.

A Schiff base, N,N′-(3,4-dithiahexane-1,6-diyl)bis(5-methylsalicylideneimine), was synthesized and characterized by X-ray crystallography. Dimeric complexes of nickel(II), palladium(II), and vanadium(IV) were synthesized by the reactions of the Schiff base with nickel(II) acetate, palladium(II) acetate, and vanadyl acetylacetonate in 1:1 molar ratio. In all three complexes, the thiol group was deprotonated and coordinated to the metal. The X-ray structure of the Schiff base showed that in the crystalline form, the SH groups were oxidized to the corresponding disulfide. In the dimeric complexes, coordination took place through the azomethine nitrogen, enolic oxygen, and sulfur atoms. The metal-to-ligand ratio was 1:1, and molar conductance data revealed that the metal complexes were nonelectrolytes. The free Schiff base and its complexes showed photoluminescence in methanol at room temperature. The redox behavior of the compounds was studied by cyclic voltammetry in DMF, which showed both quasi-reversible and irreversible processes. The interaction of the complexes with DNA was investigated by electronic absorption spectroscopy. © 2016 Springer International Publishing.

The synthesis of a new Schiff base ligand was investigated by the reaction of ferrocenecarboxaldehyde, [(η5(C5H5) (η5(C5H4CHO)], with 2-aminoethanethiol at room temperature. For this product, ring closure was also observed in the crystalline form which thiazolidine was obtained. Furthermore, new homobimetallic complexes of nickel(II) and palladium(II) were synthesized by the reaction of the new Schiff base ligand with nickel chloride and palladium chloride in 1:1 M ratio. In nickel and also palladium complexes the ligands were coordinated to the metals via the imine N atoms and the chlorido-bridged unit for the reported complexes was suggested. The complexes have been found to possess 1:1 metals to ligands stoichiometry. The emission and absorption spectra of the ligand and its complexes were studied in methanol solvent. Electrochemical properties of the ligand and its metal complexes were investigated in CH3CN solvent at the 100 mVs-1 scan rate. The Schiff base ligand and its metal complexes showed both reversible and irreversible processes at this scan rate. These compounds have been characterized by IR, 1H NMR, UV/Vis and elemental analysis. The crystal structure of the thiazolidine has been determined by single crystal X-ray diffraction. © 2015 Elsevier B.V. All rights reserved.

Interaction of 1,3-bis(2-hydroxy-benzylidene)-urea (H2L1), 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea (H2L2) and 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea nickel(II) (NiL2) with calf-thymus DNA were investigated by UV-vis absorption, fluorescence emission and circular dichroism (CD) spectroscopy as well as cyclic voltammetry, viscosity measurements, molecular docking and molecular dynamics simulation. Binding constants were determined using UV-vis absorption and fluorescence spectra. The results indicated that studied Schiff-bases bind to DNA in the intercalative mode in which the metal derivative is more effective than non metals. Their interaction trend is further determined by molecular dynamics (MD) simulation. MD results showed that Ni derivative reduces oligonucleotide intermolecular hydrogen bond and increases solvent accessible surface area more than other compounds. © 2015 Elsevier B.V.

(Chemical Equation Presented) A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s-1 scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction. © 2014 Elsevier B.V. All rights reserved.

A symmetrical tetradentate Schiff base ligand was derived by the condensation of ortho-vanillin and thiourea in 2:1 molar ratio and adjusted pH. Nickel and vanadyl complexes were obtained using the template method by the reaction of ortho-vanillin and thiourea with Ni(OAc)2. 4H2O and VO(acac)2 (2:1:1 molar ratio) in absolute ethanol and adjusted pH. The Schiff base ligand and its complexes have been characterized by FT-IR, 1H NMR, UV/Vis, elemental analysis and conductometry measurements. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metal to ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited tetrahedral and square pyramidal coordination geometry, respectively. The emission spectra of the ligand and its complexes were studied in DMSO. Electrochemical properties of the ligand and its complexes were also investigated in the DMF solvent at the 150 mVs-1 scan rate. © 2015 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany.

A new organoplatinum(II) complex containing 2,2′-biquinoline ligand (biq) was synthesized by the reaction of [Pt(p-MeC6H4)2(SMe2)2] with 2,2′-biquinoline in a 1:1 molar ratio. In this complex the ligand was coordinated to metal via the chelating nitrogen donor atoms. Also, platinum(IV) complex was obtained by the oxidative addition reaction of the methyl iodide with the platinum(II) complex in acetone. The platinum complexes have been found to possess 1:1 metal to ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The platinum(II) and platinum(IV) complexes exhibited square planar and octahedral coordination geometry, respectively. The emission spectra of the platinum(II) and platinum(IV) complexes were studied in dichloromethane. Furthermore, electrochemical properties of the metal complexes were investigated in dimethylformamide (DMF) solvent at 150 mV s-1 scan rate. The ligand and metal complexes showed both reversible and irreversible processes at this scan rate. The complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analysis and conductometry. The crystal structure of the platinum(II) complex containing 2,2′-biquinoline has been determined by single crystal X-ray diffraction. Moreover, kinetic studies of the oxidative addition reaction of methyl iodide with the platinum(II) complex in different temperatures were investigated. It was indicated that the reaction occurred by the SN2 mechanism. The rate of reaction in two different solvents was compared and the activation parameters were determined. © 2015 Elsevier B.V. All rights reserved.

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction. © 2014 Elsevier B.V. All rights reserved.

A recently new synthesized azo Schiff base was studied to characterize its ability as a cation carrier in PVC membrane solid contact electrode. The coated glassy carbon electrode (CGCE) prepared with the azo Schiff base showed excellent response characteristics to hydrogen ions. The electrode exhibited Nernstian slope of 58.8 mV/decade over a wide concentration range of H + ion from 2.0 × 10-7 to 1.8 × 10-1 M. It possessed fast response time, satisfactory reproducibility, appropriate lifetime, and most importantly, good selectivity toward H+ relative to a wide variety of other cations. The cations that usually interfere in the function of pH glass electrode such as Na+ and K+ didn't show any significant interference on the response of the proposed electrode. The effect of different non-aqueous media on the response of electrode was investigated. The electrode was applied as an indicator electrode in acid-base titration. The applicability of the electrode was tested by determination of H+ in milk as a good matrix solution and the results were compared with those obtained by the glass pH-electrode. © 2013 The Electrochemical Society.

The construction and evaluation of a novel modified carbon paste electrode with high selectivity toward oxalate ion are described. The constructed carbon paste potentiometric sensor for oxalate ion is based on the use of a zirconium salan complex as a good ionophore in the carbon paste matrix. The electrode exhibits a Nernstian slope of 29.1 mV/decade to oxalate ion over a wide concentration range from 1.5×10-6 to 3.9 ×10-2 mol L-1 with a low detection limit of 7.0×10-7 mol L-1. The electrode possesses fast response time, satisfactory reproducibility, appropriate lifetime, and most importantly, good selectivity toward C2O42- relative to a variety of common anions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 2.5-8.0. The modified carbon paste electrode was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of oxalate ion in mineral water, blood serum and urine samples. © 2013 Elsevier B.V.

A synthesized Schiff base ligand was studied to characterize its ability as a cation carrier in a poly(vinyl chloride) (PVC) membrane coated wire electrode. The constructed coated wire electrode showed excellent response characteristics to lead(II) ions. The electrode exhibits Nerns-tian slope of 29.1 mV/decade at 20 °C over a wide concentration range of Pb 2+ ions from 1.5 × 10 -6 to 1.3 × 10 -1 M with a low detection limit of 9.0 × 10 -7 M. The proposed potentiometric sensor has the following advantages: a very fast response, high reproducibility, long lifetime, and, most importantly, good selectivities relative to a wide variety of other cations. The selectivity behavior of the proposed Pb +-selective electrode revealed a considerable improvement compared with the previously reported PVC membrane electrodes for lead(II) ions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 3.5-7.5. The performance of the proposed electrode was investigated in partially non-aqueous media. The electrode was successfully applied to determine Pb + ions in mineral water, blood serum, and alloy samples. © 2011 Springer-Verlag.