Muhammet Kose

A novel Schiff base: Synthesis, structural characterisation and comparative sensor studies for metal ion detections.

A novel Schiff base ligand was synthesized by the condensation reaction of 2,6-diformylpyridine and 4-aminoantipyrine in MeOH and characterised by its melting point, elemental analysis, FT-IR, (1)H, (13)C NMR and mass spectroscopic studies. Molecular structure of the ligand was determined by single crystal X-ray diffraction technique. The electrochemical properties of the Schiff base ligand were studied in different solvents at various scan rates. Sensor ability of the Schiff base ligand was investigated by colorimetric and fluorometric methods. Visual colour change of the ligand was investigated in MeOH solvent in presence of various metal ions Na(+), Mg(2+), Al(3+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+). Upon addition of Al(3+) ion into a MeOH solution of the ligand, an orange colour developed which is detectable by naked eye. Fluorescence emission studies showed that the ligand showed single emission band at 630-665nm upon excitation at 560nm. Addition of metal ions Na(+), Mg(2+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) (1:1M ratio) cause fluorescence quenching, however addition of Al(+3) resulted in an increase in fluorescence intensity. No significant variation was observed in the fluorescence intensity caused by Al(3+) in presence of other metal ions. Therefore, the Schiff base ligand can be used for selective detection of Al(3+) ions in the presence of the other metal ions studied.

Synthesis, characterization and non-linear optical properties of two mononuclear Cu(II) complexes of 2,6-bis(1-butylbenzimidazol-2-yl)pyridine

Abstract Two copper(II) complexes, [Cu(L)(N3)2]·MeOH and [Cu(L)(NCS)2]·MeOH, were prepared and characterized by spectroscopic, analytical, and quantum chemical studies, where L is 2,6-bis(1-butylbenzimidazol-2-yl)pyridine. X-ray quality crystals of [Cu(L)(N3)2]·MeOH were obtained by slow evaporation of MeOH solution of the complex. Molecular structure of [Cu(L)(N3)2]·MeOH was determined by X-ray crystallography. The asymmetric unit contains one [Cu(L)(N3)2] and one MeOH molecule. Cu(II) in [Cu(L)(N3)2]·MeOH is five-coordinate, bonded to five nitrogens (three from L and two from two azide anions). Coordination geometry around Cu(II) center is distorted square-pyramidal with τ value of 0.065. Optimized geometries, IR spectra, and non-linear optical properties of the complexes were obtained by computational studies based on density functional theory (DFT) with M062X method. NLO properties of these complexes were investigated computationally and both complexes exhibit better NLO properties than urea.

Cobalt(II), nickel(II) and copper(II) complexes of a Schiff base ligand: synthesis, structural characterization and luminescence properties

A Schiff base ligand (HL), 2,4-dimethoxy-N-(5-chloro-2-hydroxybenzylidene)-benzenamine, derived from 5-chloro-2-hydroxybenzaldehyde and 2,4-dimethoxyaniline, and its metal complexes [Co(L)2]·CH3OH (1), [Ni(L)2] (2), [Cu(L)2] (3) have been synthesized. The compounds were characterized by analytical and spectroscopic methods. In addition, the structures of the Schiff base HL and its Co(II) complex were determined by single-crystal X-ray analysis. The Co(II) center is six-coordinate, being coordinated to two imine nitrogen, two phenolate oxygen and two methoxy oxygen atoms of two crystallographically independent Schiff base ligands. Luminescence properties of HL and its complexes were investigated both in solution and in the solid state.

Antiproliferative, antioxidant, computational and electrochemical studies of new azo-containing Schiff base ruthenium(II) complexes

A new series of ruthenium(II) complexes 7–11 containing the –NN– group are synthesized and characterized via elemental analysis, and IR, UV-visible and 1H–13C NMR spectroscopy. The solid-state structures of 2, 6 and 9 are determined by single crystal X-ray diffraction studies. The antiproliferative activities of the Schiff base ligands and their ruthenium(II) complexes are investigated in vitro against non-small cell lung cancer cells (H2126), prostate adenocarcinoma cells (PC3) and breast cancer cells (MCF7). The cell proliferation tests are performed as dose-dependent assays at eight concentrations, and 5-fluorouracil is used as the positive control. Compounds 4 and 5 show higher antiproliferative activities against PC3 cells than the other synthesized compounds. Furthermore, the antioxidant capacities of the Schiff base ligands and their ruthenium(II) complexes are investigated in vitro via ferric reduction power, DPPH free radical, and ABTS cation radical scavenging activity tests. The radical scavenging activities of complexes 7–11 are found to be higher than BHT, BHA, and Trolox, which are used as positive controls. The antioxidant activity of the complexes is found to be 30–150 fold higher than the ligands. According to obtained results, the ruthenium complexes in this study may be used as antioxidant agents in the food, drug and cosmetic industries.

CCDC 1567759: Experimental Crystal Structure Determination

Related Article: Seyit Ali Gungor, Irfan Sahin, Ozge Gungor, Sultan Erkan Kariper, Ferhan Tumer, Muhammet Kose|2017|Sens.Actuators,B|||doi:10.1016/j.snb.2017.09.161

Two seven-coordinate Mn(II) complexes derived from pentadentate ligands: Structural characterization and investigation of photophysical properties

ABSTRACT Two mononuclear Mn(II) complexes derived from pentadentate ligands were prepared and characterized. Molecular structures of the complexes were determined by X-ray diffraction studies. Mn(II) ions in both structures are seven-coordinate with approximate pentagonal bipyramidal geometry where the pyridinediimine unit and phenolic or alcoholic oxygen atoms (N3O2) of the ligand are located at the pentagonal plane and two exogenous ligands at the axial positions. In the structure of [Mn(HL2)Cl(CH3OH)]·2(CH3OH), methanol solvates link complex molecules into a 1D hydrogen-bonded chain. Emission spectra of the complexes show only one emission band in the 595–625 nm range upon excitation in the 585–615 nm range.

Structural characterisation and photoluminescence of a pyridine–diimine compound

A pyridine–diimine compound N,N′-[pyridine-2,6-diyldi(E)methylylidene]bis(4-chloroaniline) is synthesised by a Schiff base condensation of 2,6-diformylpyridine with 4-chloroaniline in methanol and characterised by spectroscopic and analytical techniques. The molecular structure of the compound is determined by the single crystal X-ray diffraction study. The compound crystallizes in the monoclinic crystal system, I2/c space group with unit cell parameters a = 7.0843(12) Å, b = 6.1909(11) Å, c = 36.262(6) Å, β = 91.576(3)°, V = 1589.8(5) Å3 and Z = 4. There is an intermolecular hydrogen bonding in the molecule resulting in a 1D hydrogen bonding chain and these hydrogen bonding chains are linked by Cl…HC(aromatic) interactions forming a 2D network. Crystal packing of the compound is determined by Cl…HC and π–π interactions. In the fluorescence emission spectra in CH3CN, DMF, DMSO and EtOH, the compound shows only one emission maximum.