S. Güner

Thermal, vibrational and EPR studies of Cu(II) bromide bis(p-methylaniline) and bis(m-methylaniline) complexes.

[CuBr(2)(pMA)(2)] and [CuBr(2)(mMA)(2)] complexes (pMA: p-methylaniline, mMA: m-methylaniline) have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, and IR, Raman and EPR spectroscopic studies. Coordination effects on the vibrational spectra of the ligands have been investigated. The room temperature EPR spectra of the complexes and their simulated spectra are also discussed in detail. The vibrational and EPR spectral studies suggest that the coordination sphere around Cu(II) consist of a distorted tetragonal structure.

Oxovanadium(IV) complexes of bromo-and methoxy substituted N1,N4-diarylidene-S-methylthiosemicarbazones

Four new oxovanadium(IV) compounds were prepared by template reaction of salicyl-, 5-bromosalicyl-and 3-methoxysalicyl-aldehyde S-methylthiosemicarbazones with 2-hydroxy-, 5-bromo-2-hydroxy-and 3-methoxy-2-hydroxy-benzaldehyde in various combinations. The compounds were isolated as stable solid compounds with general formula [VO(L)] and characterized by elemental analysis, conductivity and magnetic measurements, electronic, IR and EPR spectroscopy. The X-band EPR signals recorded from powder forms of all samples have a single asymmetric line shape and theoretical fit studies proved the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors take values of g‖ < g⊥ < ge = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically well fitted Spin Hamiltonian parameters. The EPR spectra recorded from solution forms almost have isotropic character.

Synthesis, Characterization and EPR Studies of Supramolecular Porphyrazines

Supramolecular porphyrazines with eight pyridine donor groups bound through ethylthio ester bridges on the periphery have been prepared. The pyridine donors were quaternized with iodomethane to octacationic porphyrazine. The nonanuclear supramolecular porphyrazine was prepared by the coordination of peripheral pyridine donors with VO(acac)2. The paramagnetic nonanuclear structure was studied in powder and in solution form by EPR. EPR studies together with the other spectral data confirmed the presence of identical pyridine-coordinated VO(acac)2 paramagnetic centers attached to the peripheral positions of the porphyrazine core.

Tetranuclear supramolecular structures containing phthalocyanine cores

A metal-free phthalocyanine with four pyridyl donor groups, bound through ethylthio ester bridges on the periphery, have been prepared. The pyridine donors were quaternized with iodomethane to a water-soluble tetracationic phthalocyanine. The tetranuclear supramolecular phthalocyanine was prepared by the coordination of peripheral pyridine donors with VO(acac)2. The paramagnetic tetranuclear structure was studied in powder and solution forms by the electron paramagnetic resonance (EPR) technique. Electron paramagnetic resonance studies, together with the other spectral data confirmed the presence of identical pyridine-coordinated VO(acac)2 paramagnetic centers attached to the peripheral positions of the phthalocyanine core. The X-band EPR signals recorded from powder and solution forms of supramolecules have a characteristic line shape that proves the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors were calculated as g∥ < g⊥ < ge = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically fitted Spin Hamiltonian parameters.

SYNTHESIS AND ESR STUDIES OF A SOLUBLE VANADYL PORPHYRAZINE

Octakis(hexylthio)vanadyl porphyrazinate, (VOPz), was prepared from vanadyl(IV) sulfate and metal-free porphyrazine (H2Pz), which was synthesized by the cyclotetramerization of the corresponding dinitrile derivative and further treatment with trifluoroacetic acid. Intense absorption peaks at 699 and 352 nm in the electronic spectrum indicated the C4v symmetry of VOPz. ESR studies, both in solution and in powder form, confirmed the proposed structure.

DFT calculations and experimental FT-IR, dispersive-Raman and EPR spectral studies of Copper (II) chloride complex with 3-amino-1-methylbenzene

In this study, we present the synthesis and the characterization of Copper (II) chloride complex with 3-amino-1-methylbenzene (3A1MB). This complex was characterized by vibrational and EPR spectroscopic techniques and elemental analysis. The molecular structure and spectrometry of this complex: Cu(3A1MB)2Cl2 and its ligand: 3A1MB have been investigated theoretically by performing DFT/B3LYP calculations. Cu(3A1MB)2Cl2 has been optimized as two conformers and the more stable conformer is determined. The optimized geometries and calculated vibrational frequencies have been evaluated via comparison with experimental values, and the normal modes were assigned on the basis of the percent potential energy distribution (PED). A good agreement between calculated and experimental data is observed.

Electronic Structure Properties of Doped and Imperfect ZnO Sheets

Employing first principles calculations, we examined doped and imperfect ZnO sheets to reveal the electronic structure properties. We mainly investigated the imperfect sheets arising from the host atom vacancies and doped structures where group-III (Al, B, Ga) atoms were substitutionally placed. The energy band gap and electronic behavior were addressed. We revealed and confirmed that group-III dopants and a particular host atom vacancy played an essential role in the electronic structure behavior of a ZnO sheet. We observed that a Zn or O vacancy modified enormously the band gap of a ZnO sheet and that a single dopant in the supercell resulted in semiconductor-metal transition. Zero bias conductance of a group-III doped ZnO sheet was found to be sensitive to any group-III dopant when it replaced the O atom, implying the substantial role of the dopant plus a certain host atom vacancy in the principle electronic feature of a ZnO sheet.