Search

New mixed ligand complexes of nickel(II) were synthesized by using dibasic H/5-bromo-/5-chloro-/4-hydroxy-2-hydroxybenzophenone-thiosemicarbazones (L1–4H2) and [Ni(PPh3)2Cl2]. The ligands and complexes were characterized by cyclic voltammetry, infrared, 1H and 31P NMR spectroscopy techniques. Crystallographic analyses of the 5-bromo-substituted (2) and 5-chloro-substituted (3) complexes as representatives were performed and so confirmed the ONS chelate structure and presence of PPh3 as co-ligand in the complexes. To reveal the antioxidant properties of the compounds, TEAC values (by CUPRAC method) were determined along with free radical-scavenging activity (by DPPH method). The compounds bearing 4-hydroxy substituent, L4H2 and complex 4 were the most effective compounds. The relationship between structure and antioxidant capacity in the context of benzophenone substituents and nickel(II) center was evaluated. Electrochemical results revealed that all complexes displayed metal-centered and ligand-centered redox processes. The antioxidant capacities of complexes were well correlated to electrochemical parameters.

The nickel(II) complexes containing with ONS chelating 3-methoxy-salicylaldehyde-N4-R thiosemicarbazones (R:-H2,-propyl) and triphenylphosphine coligands have been synthesized. The structures of Ni(II)-centered metal complexes were approved by means of analytical and spectroscopic data. The solid-state structure of complex 2 bearing PPh3 as co-ligand was clarified by single crystal X-ray crystallography, which revealed square planar geometry around Ni(II) ion. The potential of these complexes to inhibit the DNase I enzyme, which uses DNA as a substrate, was investigated in vitro. The results revealed that the compounds inhibited the DNase enzyme directly and/or indirectly (by masking of DNA molecules) at ≥0.1 µg/mL concentrations in vitro. © 2018, Turkish Chemical Society. All rights reserved. Istanbul Üniversitesi: BYP-2018-27646 Marmara Üniversitesi This research was supported by Research Fund of Istanbul University (BYP-2018-27646). I dedicate this paper to Dr. Bahri ÜLKÜSEVEN and Dr. Tülay BAL-DEMİRCİ, the mentors of my research career. I’m grateful to Dr. Kadir TURAN, from Faculty of Pharmacy Marmara University, for assistance with DNase I inhibition studies and this useful discussions.

Guveli, Sukriye/0000-0001-7384-822X; Ulkuseven, Bahri/0000-0001-6342-1505; Ozdemir, Namik/0000-0003-3371-9874 WOS: 000377728600003 Two nickel(II) complexes containing 5-bromosalicylidene-N-methyl-S-methyl-isothiosemicarbazone (H(2)SMeNMeTsc) and 5-bromosalicylidene-N-methyl-thiosemicarbazone (H(2)NMeTsc) with triphenylphosphine were synthesized. The compounds were characterized by elemental analysis, IR, H-1 NMR and UV-Vis spectroscopies, and their structures were determined by single crystal X-ray diffraction technique. Theoretical characterization of the compounds was carried out using the density functional theory (DFF/B3LYP) method with 6-311G(d,p) basis set for the C, H, Br, N, O, P, S atoms and LANL2DZ pseudo-potential for Ni atom, and the results were checked against the experimental data. Electronic absorption spectra of the compounds have also been obtained using the time-dependent density functional theory (TD-DFT) formalism at the same level. The coordination geometry around Ni-II in the two complexes is distorted square-planar geometry. While the thiosemicarbazone ligand is coordinated to nickel through ONN mode in [Ni(SMeNMeTsc)(PPh3)]center dot PPh3, it is bound to the metal as dianionic ONS donors in [Ni(NMeTsc)(PPh3)]. The consistency between theoretical and experimental values is good in general. (C) 2016 Elsevier Ltd. All rights reserved. Scientific Research Projects Coordination Unit of Istanbul UniversityIstanbul University This work was supported by the Scientific Research Projects Coordination Unit of Istanbul University. We also thank Associate Professor Mustafa Serkan Soylu, Giresun University, Turkey, for his help with the X-ray data collection of complex [Ni(SMeN-MeTsc)(PPh3)]center dot PPh3.

Ulkuseven, Bahri/0000-0001-6342-1505; Ozdemir, Namik/0000-0003-3371-9874; SOYLU, SERKAN M/0000-0002-8440-1260 WOS: 000461331500002 Mixed ligand Ni(II) complexes were synthesized from triphenylphosphine and S-methyl- or S-ethyl-isothiosemicarbazone ligands derived from 3-bromo-5-chloro-2-hydroxy-benzaldehyde. The complexes were characterized by physicochemical and spectroscopic methods. In addition, their molecular structures were determined by single-crystal X-ray diffraction. In both complexes, the Ni atom has a near square-planar geometry, being coordinated by the phenolato oxygen, azomethine nitrogen and amine nitrogen atoms of the thiosemicarbazone ligands, together with the phosphorus atom of the triphenylphosphine. The S-methyl complex includes an additional free thiosemicarbazone ligand in the asymmetric unit. X-ray analysis shows that O-HN, N-HN, C-HN and C-HO-type hydrogen bonds and - stacking interactions are responsible for stabilizing the crystal structures. Scientific Research Projects Coordination Unit of Istanbul UniversityIstanbul University [BYP-2017-21222] This work was supported by the Scientific Research Projects Coordination Unit of Istanbul University (Project Number: BYP-2017-21222).

Tetra-coordinated nickel(II) complexes of two ONS (1, \2) and seven ONN (3a-3g) chelating 2-hydroxy-3-methoxy-benzaldehyde thiosemicarbazones were synthesized. The dibasic ligands and complexes bearing PPh$_{3}$ as a coligand were characterized by means of analytical and spectroscopic data. Cytotoxic activities of the ligands and nickel(II) complexes were determined using the MTT assay in vitro against MDCK cells, and then all the compounds were tested on influenza virus replication by plaque assays. The compounds showed GI$_{50}$ values varying from concentrations of 15.9 up to 161.8 $\mu$ g/mL for MDCK cells. The plaque assays indicated that one ONS (1) and two ONN (3c and 3d) chelate structures have considerable antiviral effects on influenza A viruses at lower concentrations than the GI$_{50}$ values for MDCK cells. The ligands and other complexes did not show any inhibitory effects on influenza virus plaque formation. The effects of the compounds on the influenza virus and structure-antiviral activity relationships were discussed based on the donor atoms and S-alkyl substituents

Guveli, Sukriye/0000-0001-7384-822X; Ulkuseven, Bahri/0000-0001-6342-1505 WOS: 000446286200042 A tridentate Schiff base ligand (5-methyl-2-hydroxy-acetophenone-S-methyl-thiosemicarbazone, H2L) and its mononuclear nickel complex, [NiL(PPh3)], were obtained and characterized by spectroscopic techniques. Structural analysis of the compounds was supported by complementing crystallographic studies. The X-ray data related to molecular geometries was used in the DFT/B3LYP calculations with 6-311G (d, p) and LANL2DZ (for nickel atom) basis sets. Atomic charge distribution data indicated that the negative charges of free thiosemicarbazidato ligand were transferred to nickel (II) by the formation of the metal complex. To understand the nucleophilic or electrophilic reaction capabilities the ligand and nickel complex, the molecular electrostatic potential (MEP) and electrostatic potential (ESP) analyses have performed. (C) 2018 Elsevier B.V. All rights reserved. University Research Fund [F.279]; BAP (The Scientific Research Projects Coordination Unit of Istanbul University (Turkey)) [23552] The authors acknowledge the Scientific and Technological Research Application and Research Center of Sinop University (Turkey) for the use of the Bruker D8 QUEST diffractometer. The authors sincerely thank Ondokuz Mayis University (Turkey) for providing analysis using the STOE IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund). This work was also supported by the BAP (The Scientific Research Projects Coordination Unit of Istanbul University (Turkey), Project Numbers: 23552).

Aygun, Muhittin/0000-0001-9670-9062; Guveli, Sukriye/0000-0001-7384-822X; Ulkuseven, Bahri/0000-0001-6342-1505; Aygun, Muhittin/0000-0001-9670-9062 WOS: 000403118200001 This work presents a combined experimental and theoretical study on new synthesized ONN and ONS chelating 2-hydroxyacetophenone thiosemicarbazone ligands and their nickel(II) complexes with triphenylphosphine co-ligand. The 5-bromo-2-hydroxyacetophenone thiosemicarbazone ligand (L-1) coordinates to nickel through the phenolic-O, azomethine-N and thiole-S atoms and the complex [Ni(L-1) (PPh3)] (1) is formed an ONSP donor set with P atom of triphenylphosphine ligand. The 5-bromo-2-hydroxyacetophenone-S-methyl-thiosemicarbazone ligand (L-2) is functional a thioamide nitrogen instead of a sulfur atom, so complex [Ni(L-2)(PPh3)] (2) have ONNP donor set. The spectroscopic properties of all compounds have been determined by IR, H-1 NMR and UV-Vis spectroscopy techniques and the crystal structure of L-1, 1 and 2 have also been studied using X-ray diffraction. The molecular geometries obtained by X-ray analyzes in the ground state were compared with the optimized geometries which were calculated using the DFT/B3LYP method. The 6-311G(d,p) basis set for C, H, N, O, P, S atoms and LANL2DZ basis set for Ni atom were chosen in all theoretical calculations. In addition to molecular geometries, the vibrational frequencies, electronic transitions and H-1 NMR chemical shifts of the compounds were computed and compared with the experimental values. The electronic absorption spectra of the both complexes were predicted by using the time-dependent DET method. The HOMO-LUMO analyses were carried out and the chemical reactivity parameters (chemical hardness and softness, electronegativity, chemical potential and electrophilicity index) were calculated for studied compounds. (C) 2017 Elsevier Ltd. All rights reserved. Dokuz Eylul University, TurkeyDokuz Eylul University [2010.KB.FEN.13]; Ondokuz Mayis University, TurkeyOndokuz Mayis University [F.279] The authors acknowledge Dokuz Eylul University, Turkey, for the use of the Agilent Xcalibur Eos diffractometer (purchased under University Research Grant No.: 2010.KB.FEN.13) and Ondokuz Mayis University, Turkey, for the use of the STOE IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund).

Mixed ligand nickel(II) and ruthenium(II) complexes were synthesized from pyridoxal-N-allyl-thiosemicarbazone hydrochloride and triphenylphosphine. The structures of the complexes have been characterized by elemental analysis, IR, 1H and 31P NMR, conductivity, magnetic moment measurements and single-crystal X-ray diffraction technique. Based on X-ray crystallographic studies, a square-planar structure has been proposed for the Ni(II) complex, in which the thiosemicarbazone ligand acts as dianionic tridentate ONS ligand. In the case of the Ru(II) complex, the thiosemicarbazone is coordinated to metal atom as a monoanionic bidentate NS donor ligand in an octahedral geometry. Antioxidant activities of the ligand and its metal complexes were calculated as their trolox equivalent antioxidant capacities (TEAC) by CUPRAC method and DPPH assay. Both the ligand and its metal complexes were found to be antioxidant and are much more antioxidant at least 2.1 times than trolox, even, ligand is 3.5 times greater than that of trolox according to CUPRAC. A linear correlation (correlation coefficient R2 = 0.9997) appeared between the obtained TEAC values by the two antioxidant assays. © 2019 Elsevier B.V.

The complexes [Ni(L1)(PPh3)] (1) and [Ni(L2)(PPh3)]·HCl (2) were synthesized by the reaction of [Ni(PPh3)Cl2] and dibasic 2-hydroxyacetophenone-S-R-4-R1-thiosemicarbazones (R/R1: H/CH3, L1H2; CH3/H, L2H2). The ligands and the complexes were characterized using elemental analysis, IR and 1H NMR spectra. In both complexes, the thiosemicarbazone ligands coordinate to nickel(II) by giving two protons. Complex 1 is formed through the phenolate oxygen, azomethine nitrogen and sulfur atoms of L1 and the P atom of a triphenylphosphine ligand. In complex 2, L2 is functional through an ONN donor set, containing a thioamide nitrogen instead of a sulfur atom. X-ray analysis indicated distorted square planar structures for the complexes, and the nickel atoms lie slightly above the planes structured by the donor atoms. In the crystal forms of 1 and 2, some phenyl ring protons of the phosphine ligand give intramolecular hydrogen bonds with the donor atoms of the thiosemicarbazone moiety, namely the phenolate oxygen (in complexes 1 and 2) and N4 nitrogen (in complex 2).

Ozdemir, Namik/0000-0003-3371-9874; Andac, Omer/0000-0003-3641-9690; Ulkuseven, Bahri/0000-0001-6342-1505; Guveli, Sukriye/0000-0001-7384-822X WOS: 000280898800002 Reaction of 2-hydroxyacetophenone thiosemicarbazone with [Ni(PPh(3))(2)Cl(2)] in optimized conditions afforded a mixed ligand complex with an isolated triphenylphosphine molecule. The structure was characterized by elemental analysis, IR, NMR and UV-Vis. spectroscopies and single crystal X-ray diffraction technique. In addition, the molecular geometry, vibrational frequencies and gauge including atomic orbital (CIAO) (1)H and (13)C NMR chemical shift values of the title compound in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-31G(d,p) basis set for the C. N, O, S, P. H atoms and LANL2DZ pseudo-potential for the Ni atom, and compared with the experimental data. Besides, atomic charge distributions, molecular electrostatic potential and frontier molecular orbitals (FMO) analysis of the title compound were investigated by theoretical calculations. The thermodynamic properties of the compound at different temperatures have been calculated and corresponding relations between the properties and temperature have also been obtained. Atomic charge distributions indicate that during forming the title compound, the free ligand of thiosemicarbazone ion transfers their negative charges to central Ni(II) ion. The effect of different solvents (chloroform, methanol and water) on the geometry, vibrational frequencies, total energies and dipole moments was studied using the density functional theory (DFT/B3LYP) method by applying the Onsager and the Polarizable Continuum Model (PCM). (C) 2010 Elsevier Ltd. All rights reserved. istanbul UniversityIstanbul University; Research Centre of Ondokuz May's UniversityOndokuz Mayis University [F-461] Funding of our research from the Research Fund of istanbul University and the Research Centre of Ondokuz May's University (Project No: F-461) is gratefully acknowledged.

Ozdemir, Namik/0000-0003-3371-9874; Guveli, Sukriye/0000-0001-7384-822X; Ulkuseven, Bahri/0000-0001-6342-1505 WOS: 000265835400003 Reactions of 5-bromo-2-hydroxy-benzaldehyde-S-R-4-R-1-thiosemicarbazones, [R, R-1 = H,H (L-1); CH3, H (L-2); H, C6H5 (L-3); CH3, C6H5 (L-4)] with [Ni(PPh3)(2)Cl-2] in 1:1 molar ratio yielded complexes of general formula [Ni(L)(PPh3)]. While the complexes of L-1 and L-3 involve the ONS donor set of the thiosemicarbazone, the L-2 complexes utilize the ONN set. The reaction of L-4 and the nickel salt gave the L-3 complex by loss of the CH3 group from the sulphur. The complexes were characterized by physico-chemical and spectroscopic methods. The structures of the L-1 and L-2 complexes have been determined by single crystal X-ray diffraction and a new coordination mode (ONN) of salicylaldehyde thiosemicarbazones has been identified. Research Fund of Istanbul UniversityIstanbul University [T-957/06102006] This work was supported by the Research Fund of Istanbul University. Project No. T-957/06102006.

Ulkuseven, Bahri/0000-0001-6342-1505; Guveli, Sukriye/0000-0001-7384-822X WOS: 000370900600015 A new 5-methyl-2-hydroxy-acetophenone-thiosemicarbazone ligand (L) and its nickel(II) complex [Ni(L)(PPh3)] were synthesized. The crystal structure of free ligand and its complex has been determined by single crystal X-ray diffraction technique. In the complex, thiosemicarbazone ligand is coordinated to nickel through ONS mode. The structures were also characterized by elemental analysis, IR, H-1 NMR and UV-Vis. spectroscopies. In addition, the molecular geometries, vibrational frequencies and gauge independent atomic orbital (GIAO) H-1 NMR chemical shift values of the compounds in the ground state have been calculated using the density functional theory (B3LYP) method with 6-311G(d,p) basis set for C, H, N, O, P, S atoms and LANL2DZ basis set for Ni atom. Electronic transitions were calculated using the time-dependent density functional theory (TD-DFT) formalism and the experimental spectra of the compounds have been discussed. (C) 2015 Elsevier Ltd. All rights reserved. Dokuz Eylill University, TurkeyDokuz Eylul University [2010.KB.FEN.13]; Ondokuz Mayis University, TurkeyOndokuz Mayis University [F.279] The authors acknowledge Dokuz Eylill University, Turkey, for the use of the Agilent Xcalibur Eos diffractometer (purchased under University Research Grant No: 2010.KB.FEN.13) and Ondokuz Mayis University, Turkey, for the use of the STOE IPDS 2 diffractometer (purchased under Grant F.279 of the University Research Fund).

Guveli, Sukriye/0000-0001-7384-822X; Ulkuseven, Bahri/0000-0001-6342-1505; Ozdemir, Namik/0000-0003-3371-9874 WOS: 000375518900024 The cationic thiosemicarbazone complex of nickel containing triphenylphosphine as coligand was synthesized through the isopropanol-assisted hydrogen transfer reaction. The thiosemicarbazone ligand (LH2) and its cationic nickel complex, [Ni(LH)(PPh3)]Cl-+(-)center dot(CH3)(2)CHOH, were characterized by elemental analysis, IR, H-1 NMR and UV-Vis spectroscopies. The molecular structure of the complex was also determined by single crystal X-ray diffraction technique. In addition computational studies at B3LYP/6-311G (d,p) (main group) and LANL2DZ (Ni) level were carried out for theoretical characterization of the ligand and complex. Structural analysis of the complex indicated the presence of square-planar coordination geometry (ONNP) about nickel in which the thiosemicarbazone ligand coordinated as mononegative tridentate. Isopropyl alcohol catalyzed efficiently the transfer hydrogenation and the cationic complex formed through inter conversion azinyl-azinylidene. All spectral data support the formation of the ligand and its nickel complex and the results calculated using theoretical methods coincide well with the experimental findings. The thermal degradation of the complex was investigated using thermogravimetric and differential thermal analyses techniques in nitrogen and oxygen atmosphere. The oxidative-thermal decomposition of the compound showed volatilization of nickel as unexpected behavior unlike nitrogen atmosphere. (C) 2016 Elsevier Ltd. All rights reserved. Istanbul UniversityIstanbul University This work was supported by the Research Fund of Istanbul University.

Ulkuseven, Bahri/0000-0001-6342-1505; Guveli, Sukriye/0000-0001-7384-822X; Ozdemir, Namik/0000-0003-3371-9874; KOCA, ATIF/0000-0003-0141-5817 WOS: 000369070900002 Reactions of [Ni(PPh3)(2)Cl-2] with 3-Bromo-5-chloro-2-hydroxyacetophenone-N-4-hexyl ((LH2)-H-1), cyclohexyl (L2H2) and phenyl ((LH2)-H-3)-thiosemicarbazones resulted in four coordinated (ONSP) nickel(II) complexes, [Ni(L-1)(PPh3)] (1), [Ni((LH)-H-2)(PPh3)]center dot Cl (2) and [Ni(L-3)(PPh3)]center dot C2H5OH (3). The structures of 1-3 were determined by spectroscopic and single crystal X-ray diffraction methods. While formation of complexes 1 and 3 occurs through the doubly deprotonated forms of the thiosemicarbazone ligands (L-1 and L-3), complex 2 consists of mono deprotonated ligand ((LH)-H-2). Cyclic voltammetry and square wave voltammetry studies of the compounds showed that all ligands represented one irreversible reduction and two irreversible oxidation processes. Complexes 1-3 illustrated a metal based reduction and a metal based oxidation processes in addition to the ligand based electron transfer reactions. In situ spectroelectrochemical measurements were employed to determine the spectra of electrogenerated species of the complexes and to assign the redox processes. The influences of the N-4-substituent types on structural and electrochemical features of the compounds were discussed. (C) 2015 Elsevier B.V. All rights reserved. TUBA (The Turkish Academy of Sciences)Turkish Academy of Sciences; BAP (The Scientific Research Projects Coordination Unit of Istanbul University)Istanbul University [YOP 40652, UDP 55762] This work was supported TUBA (The Turkish Academy of Sciences) and BAP (The Scientific Research Projects Coordination Unit of Istanbul University, Project Numbers: YOP 40652, UDP 55762.).

Guveli, Sukriye/0000-0001-7384-822X; Ozdemir, Namik/0000-0003-3371-9874; KOCA, ATIF/0000-0003-0141-5817; Ulkuseven, Bahri/0000-0001-6342-1505 WOS: 000343922800061 Mixed ligand nickel(II) complexes of 5-chloro-2-hydroxybenzophenone-N-R-thiosemicarbazone (R: -CH3 (L-1), -CH2-CH=CH2 (L-II)) and triphenylphosphine were synthesized. The structures of the complexes were characterized by elemental analysis, IR, H-1 and P-31 NMR spectroscopy, conductivity, electrochemical and magnetic moment measurements, and single-crystal X-ray diffraction technique. The two nickel(II) complexes have a square planar geometry containing O, N, and S atoms of the thiosemicarbazone, and the P atom of triphenylphosphine. The electrochemical behaviors of the thiosemicarbazone ligands and the nickel complexes were studied using cyclic voltammetry and square wave voltammetry. The redox processes of the compounds were significantly influenced by the central metal ions and the nature of the substituents on the thiosemicarbazones, which are the important factors in controlling the redox properties. In situ spectroelectrochemical studies were employed to determine the colors and spectra of the electro-generated species of the complexes. Scientific Research Projects Coordination Unit of Istanbul UniversityIstanbul University [BAP 16682, UDP-26770] This work was supported by the Scientific Research Projects Coordination Unit of Istanbul University (Project Numbers: BAP 16682 and UDP-26770).