İbrahim Uçar

Spectroscopic characterization, X-ray structure, antimicrobial activity and DFT calculations of novel dipicolinate copper(II) complex with 2,6-pyridinedimethanol

Novel dipicolinate complex of copper(II) ion, [Cu(dmp)(dpc)]·0.8H(2)O [dmp: 2,6-pyridinedimethanol; dpc: dipicolinate or pyridine-2,6-dicarboxylate], has been prepared and fully characterized by single crystal X-ray structure determination. The central copper(II) ion is bonded to dpc and dmp ligands through pyridine nitrogen atom together with two oxygen atom, forming the distorted octahedral geometry. The complex molecules, connected via O-H···O hydrogen bonds, form a supramolecular structure. H(2)dpc, [Cu(dpc)(H(2)O)(3)] and [Cu(dmp)(dpc)]·0.8H(2)O were screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and yeast. H(2)dpc and [Cu(dpc)(H(2)O)(3)] exhibited antibacterial and antifungal activity, while [Cu(dmp)(dpc)]·0.8H(2)O exhibited activity only for Gram-positive bacteria. The geometry optimization and EPR parameters were carried out using the following unrestricted hybrid density functionals: LSDA, BPV86, B3LYP, B3PW91, MPW1PW91, PBEPBE and HCTH. Although the supramolecular interactions have some influences on the molecular geometry in solid state phase, calculated data show that the predicted geometries can reproduce the structural parameters. The electronic station in the frontier orbitals of the copper complex calculated from the experimental data is compared to the results of time-depended DFT calculations with the polarizable continuum model. Calculated vibrational frequencies are consistent with the experimental IR data.

Preparations, IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)2Pd(CN)4] (1) and [Cd(hydet-en)2Pd(CN)4] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H ··· O, N–H ··· N and O–H ··· N, thereby forming a three-dimensional network.

Structural characterization and EPR spectral studies on mononuclear copper(II) complex of saccharin with ethylnicotinate

Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)(2)(sac)(2)(H(2)O)].1.4H(2)O has been synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. It crystallizes in the tetragonal crystal systems with space group I4(1)cd and Z=8. The copper(II) ion presents a CuN(4)O distorted square pyramidal coordination. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110K), indicate the presence of the unpaired electron in the d(x)(2)-(y)(2) orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sigma and in-plane pi-bonding. Some comparisons with related structures are made and the most important features of its IR spectrum were also discussed. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centred electroactivity in the potential range +/-1.25 V vs. Ag/AgCl reference electrode.

Crystal structure and EPR studies of mixed ligand complex of cobalt(II) with saccharin and ethylisonicotine

The tetraaquabis(ethylisonicotinate)cobalt(II) disaccharinate, [Co(ein)2(H2O)4].(sac)2, (CENS), (ein: ethylisonicotinate and sac: saccharinate) complex has been synthesized and its crystal structure has been determined by X-ray diffraction analysis. The title complex crystallizes in monoclinic system with space group P2(1)/c and Z=2. The Co(II) cations present a slightly distorted CoN2O4 octahedral environment, with equatorially coordinated water molecules and axially pyridine N-bound ethylisonicotinate ligands. The magnetic environments of Cu2+-doped Co(II) complex have been identified by electron paramagnetic resonance (EPR) technique. Cu2+-doped CENS single crystals have been studied at room temperature in three mutually perpendicular planes. The calculated results of the Cu2+-doped CENS indicate that Cu2+ ion substitute with the Co2+ ion in the host lattice. The angular variations of the EPR spectra have shown that two different Cu2+ complexes are located in different chemical environments, and each environment contains two magnetically inequivalent Cu2+sites in distinct orientations occupying substitutional positions in the lattice and show very high angular dependence. The cyclic voltammogram of the title complex investigated in dimethylformamide (DMF) solution exhibits only metal centered electroactivity in the potential range -1.0-1.25V versus Ag/AgCl reference electrode.

An experimental and theoretical approach of spectroscopic and structural properties of a new chelidamate copper (II) complex

The crystal structure of new chelidamate complex of copper (II) ion, [Cu(chel)H2O(pym)]·H2O [chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate; pym: 2-Pyridylmethanol] has been determined by single crystal X-ray crystallographic method. The complex was characterized by IR and UV-Vis spectroscopic techniques. The magnetic environment of copper (II) ion has been defined by electron paramagnetic technique (EPR). The central copper (II) ion is six-coordinate with a distorted octahedral geometry, which exhibits Jahn-Teller distortions along one of the O-Cu-O axes with tetragonality of 0.81. Chelidamate behaved as a tridentate ligand was bonded to Cu(II) ion through carboxyl oxygens with nitrogen. The crystal structure is stabilized by O-H⋯O hydrogen bond and π-π interactions. Theoretical calculations have been carried out by using the DFT method. The modeling of copper (II) complex was made by geometric optimization. The geometry optimization and EPR study were carried out using the following unrestricted hybrid density functionals: LSDA, BPV86, B3LYP, B3PW91, MPW1PW91 and HCTH. Frontier molecular orbital energies, absorption wavelengths and excitation energy were computed by time dependent DFT (TD-DFT) method with polarizable continuum model. IR spectra were discussed and compared to other relevant complexes together with theoretical results. The natural charges on the atoms and second-order interaction energies were derived from natural bond orbital analysis (NBO).

Structural, spectroscopic and EPR studies of tetraethylammonium tetramethylammonium tetrabomocuprate (II) complex

Abstract The tetraethylammonium tetramethylammonium tetrabromocuprate(II), (hereafter, [(TEA)(TMA)CuBr4]) [(C2H5)4N][(CH3)4N][CuBr4], complex was synthesized and characterized by spectroscopic (IR), structural (XRD) and electron paramagnetic resonance (EPR) technique. The compound contains four isolated and discrete moieties, i.e. two independent [(CH3)4N]+ cations, with one on a -4 axis and the other with the central N atom on a 2z axis, one [(C2H5)4N]]+ cation, on a mirror plane and in a trans conformation, and one distorted tetrahedral [CuBr4]2– anion on another mirror plane. The electron paramagnetic resonance spectra of [(TEA)(TMA)CuBr4] single crystals and powder were investigated in the temperature range from 300 to 5 K. The observed values from the line width and g tensors were found to be temperature dependent. The temperature dependence of Cu(II) complex with EPR spectra values were also discussed in terms of dynamic Jahn-Teller effect.

Synthesis, crystal structure, EPR spectra of doped VO2+ and Cu2+ ions in [Zn(ethylisonicotinate)2(H2O)4]·(sac)2 single crystal

The tetraaquabis(ethylisonicotinate)zinc(II) disaccharinate, [Zn(ein)(2)(H(2)O)(4)].(sac)(2) (ZENS) (ein: ethylisonicotinate and sac: saccharinate) complex has been synthesized and its crystal structure has been determined by X-ray diffraction analysis. The magnetic environments of VO(2+) and Cu(2+) doped Zn(II) complex have been identified by electron paramagnetic resonance (EPR) technique. The title complex crystallizes in monoclinic system with space group P2(1)/c, Z=4. The octahedral Zn(II) ion, rides on a crystallographic centre of symmetry, is coordinated by two monodentate ein ligands through the ring nitrogen and four aqua ligands to form discrete [Zn(ein)(2)(H(2)O)(4)] unit, which captures two saccharinate ions in up and down positions, each through intermolecular hydrogen bonds. Cu(2+) and VO(2+) doped ZENS single crystals have been studied at room temperature in three mutually perpendicular planes. The calculated results of the Cu(2+) and VO(2+) doped in ZENS indicate that Cu(2+) and VO(2+) ion substitute with the Zn(2+) ion in the host lattice. The angular variations of the EPR spectra have shown that two different Cu(2+) and VO(2+) complexes are located in different chemical environments, and each environment contains two magnetically inequvalent Cu(2+)and VO(2+)sites in distinct orientations occupying substitutional positions in the lattice and show very high angular dependence. The ground state wave functions of the unpaired electron of Cu(2+) ion have been constructed and type of the distortion has, then, been determined.

EPR study of Cu2+-doped tetraaqua-di(nicotinamide)Co(II) saccharinate single crystals

The electron paramagnetic resonance spectra of Cu(2+) impurities in [Co(nicotinamide)(2)(H(2)O)(4)](saccharinate)(2) single crystals have been studied at ambient temperature in three mutually perpendicular planes. The angular variation of the spectra shows that the Cu(2+) ion substitutes the Co(2+) site in the lattice. The EPR spectra of Cu(2+) ions are characteristic of tetragonally elongated octahedral site. The spin-Hamiltonien parameters were obtained from the single crystal EPR analysis. The ground-state wave function of Cu(2+) ion in the lattice has been constructed.

Picolinamidium squarate and di-p-toluidinium squarate dihydrate.

The crystal structure determinations of picolinamidium squarate, C 6 H 7 N 2 O + .C 4 O 4 - , (I), and di-p-toluidinium squarate dihydrate, 2C 7 H 10 N + .C 4 O 4 2 - .2H 2 O, (II), are reported. While salt formation occurs by donation of one H atom from squaric acid to the picolinamide molecule in (I), in compound (II), each squaric acid molecule donates one H atom to the p-toluidine N atom of two trans p-toluidine molecules. In (I), the pyridine ring is coplanar with the squarate monoanion through imposed crystallographic mirror symmetry; in (II), the dihedral angle between the p-toluidine moiety and the squarate dianion is 70.71(1)°. In (I), a three-dimensional structure is formed via van der Waals interactions between parallel planes of molecules, with hydrogen-bond interactions (N-H...O and O-H...O) acting within the planes; hydrogen bonds form a three-dimensional network in (II).

Bis(1,10-phenanthroline-κ2N,N′)(squarato-κO)copper(II) trihydrate

The title mononuclear [Cu(sq)(phen) 2 ].3H 2 O complex [sq is squarate (C 4 O 4 ) and phen is 1,10-phenanthroline (C 12 H 8 N 2 )] has been synthesized and the structure consists of a neutral mononuclear [Cu(sq)(phen) 2 ] unit and three solvate water molecules. The Cu II ion has distorted square-pyramidal coordination geometry, comprised of one carboxylate O atom from a monodentate squarate ligand and four N atoms from two chelating phen ligands. An extensive three-dimensional network of OW-H...O/OW hydrogen bonds, face-to-face π-π interactions between the 1,10-phenanthroline aromatic rings and a weak π-ring interaction are responsible for crystal stabilization.