Hatice Vural

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).

A combined theoretical and experimental study of chelidamate cadmium (II) complex, [Cd2(dpa)2(chel)2]⋅2[Cd(dpa)(chel)]⋅6H2O

A new chelidamate complex of Cd (II) ion, [Cd2(dpa)2(chel)2]⋅2[Cd(dpa)(chel)]⋅6H2O [(chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate, dpa: di (2-picolyl)amine)] was synthesized and characterized by spectroscopic (UV-Vis and FT-IR spectroscopy) and structural (single-crystal X-ray diffraction) methods. Quantum chemical calculations were carried out by using Hartree Fock (HF) and Density Functional Theory (DFT)/B3LYP methods Stuttgart/Dresden (SDD) basis set. The asymmetric unit of the title compound contains two symmetry unrelated monomeric units, one dimeric unit and six water molecules of crystallization. The geometries around the Cd (II) metal centers in the units can be described as distorted octahedral for the monomeric units and distorted monocapped trigonal prism for the dimeric unit. The electronic structure of the complex was calculated using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability and bond strength were investigated by applying natural bond orbital analysis (NBO). The computed frequencies were compared with experimental frequencies.

Combined experimental-theoretical characterization of chelidamate nickel complex with 4-methylpyrimidine.

A new chelidamate complex of nickel(II) ion, [Ni(chel)(H2O)2(mpd)]·2H2O [chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate, mpd: 4-methylpyrimidine] was synthesized and characterized by single-crystal X-ray diffraction, UV-Vis and FT-IR spectroscopy. Intermolecular O-H⋯O and O-H⋯N hydrogen bonds and π-π stacking interactions appear to be effective in the stabilization of the crystal structure. Theoretical calculations have been carried out by using Hartree-Fock (HF)/6-31G (d) and Density Functional Theory (DFT)/6-31+G (d). Molecular geometry from X-ray experiment of Ni(II) complex in the ground state was compared using unrestricted hybrid density functional B3LYP. HOMO-LUMO energies, absorption wavelengths and excitation energy were computed by time dependent DFT (TD-DFT) method with polarizable continuum model. The observed FT-IR vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The natural charges on the atoms and second-order interaction energies were derived from natural bond orbital analysis (NBO).

A mixed experimental and theoretical study on chelidamate copper(II) complex with 4-methylpyrimidine

Abstract A new chelidamate complex, [Cu(chel)(H2O)2(mpd)] (chel = chelidamate; mpd = 4-methylpyrimidine), has been synthesized and characterized through a combination of single crystal X-ray analysis, electron paramagnetic resonance (EPR), ultraviolet-visible (UV-vis), and fourier transform infrared spectroscopy (FT-IR). The complex has six-coordinate distorted octahedral geometry around Cu(II). The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and angles) have been calculated using Density Functional Theory (DFT)/B3LYP and Hartree Fock quantum chemical methods with 6-31G(d, p) basis set by Gaussian 09W software. The EPR spectrum of the compound showed that the paramagnetic center has rhombic symmetry. The EPR studies were carried out using the following unrestricted hybrid density functionals: B3LYP, CAM-B3LYP, HSEH1PBE, WB97XD, MPW1PW91, and BPV86. The UV–vis absorption spectra have been examined in different media and compared with the calculated one using TD-DFT method by applying the polarizable continuum model. Natural bond orbital property of complex has been performed by DFT/B3LYP with 6-31G (d, p) basis set.

Two new chelidamate complexes with the 4-methoxypyridine: A combined theoretical and experimental study

Two new mixed chelidamate complexes, [M(chel)(mhpOCH3)·2H2O]·2H2O [M=Ni(II) (1); Co(II) (2); chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate; mhp: 4-methoxypyridine], were prepared and characterized through a combination of X-ray diffraction method, FT-IR and UV-Vis spectroscopy. The central M(II) ion in complex (1) and (2) is coordinated by the mhp nitrogen atom, the chel nitrogen and oxygen atoms and aqua oxygen atoms, forming the distorted octahedral geometry. Intra and intermolecular hydrogen bonds and π-π stacking interactions appear to be effective in the stabilization of the crystal structures. Also, the fully optimized geometries and vibrational frequencies have been calculated using density functional theory (DFT)-B3LYP with 6-31G (d) basis set. The vibrational frequencies were interpreted by means of potential energy distribution (PED). The energetic behaviors of the complexes in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). The molecular stability and charge delocalization were analyzed using natural bond orbital (NBO) analysis.