Investigation of the synthesis, structural, spectroscopic, electronic and non-linear optical properties of the Mn(II) and Zn(II) complexes of new 6-bromopicolinic acid

In this thesis, Mn(II) and Zn(II) complexes of 6-bromopicolinic acid {[Mn(6-Brpic)2(H2O)2] (1) and [Zn(6-Brpic)2(H2O)2·H2O] (2)} were synthesized and the crystal structures of these complexes distorted octahedral geometry coordination spheres was determined by X-ray diffraction method. Vibrational, electronic and optical spectral properties of synthesized complexes were investigated by means of FT-IR and UV-Vis spectra. Theoretical calculations were made using Gaussian 09W, Revision D.01 and GaussView 5 package program. Geometrical parameters (bond lengths, bond and dihedral angles) and vibrational frequencies were calculated using the DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ method. Electronic absorption wavelengths, oscillator strengths, transition dipole moments were obtained using the TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ method. In addition, the percentage ratios of ligand and metal ions in molecular orbitals with significant contributions from molecular orbitals to electronic transitions were determined with the SWizard and Chemissian programs. Molecular parameters such as electronegativity, chemical hardness and softness were designated from the calculated frontier molecular orbitals of the complexes. Interactions between bonds in complexes, coordination environment of metal ions and conjugative interactions were determined by natural bond orbital (NBO) analysis. The ground state dipole moment (µg), mean and anisotropy polarizability (ᾱ and Δα), refractive index (n), linear and third-order nonlinear optical sensitivity (χ(1) ve χ(3)), second- and third-order nonlinear optical (β and γ) parameters were calculated by using the DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ method. Also, the n and χ(3) values of the complexes were experimentally investigated in the middle IR and UV-Vis region (200-800 nm), respectively. The structure-property relationship in all corresponding experimental parameters theoretically calculated for the Mn(II) and Zn(II) complexes of 6-bromopicolinic acid is presented in this thesis study.