The Synthesis,Characterization And Quantum Chemical Studies On Heterocyclic Ligands And Their Complexes Containing Nitrogen

A series of novel derivatives of benzimidazole and their complexes were synthesized. Their structure were characterized by IR, 1H NMR and 13C NMR spectroscopy. Seven typical crystal structure have been studied by X-ray crystallography, and the relationship between structures and properties were presented in this paper.Thermal decomposition mechanism, fluorescence and magnetic properties of titled complexes were investigated. The procedure of thermal decomposition has been calculated by means of quantum chemistry and the theoretical criterion of their thermal decomposition, i.e. the principle of least bond order may be used here.Sixty kinds of titled complexes have been studied by using of density function theory(DFT) at the B3LYP/6-31G level, and their full optimized molecular geometry, charges distribution, IR spectra and thermodynamic function were presented.The theoretical studies on a series of complexes formed from amine [CH3NH2, ( CH3) 2NH and ( CH3) 3N] or ammonia(NH3) with benzimidazole were performed using DFT method at B3LYP/6-31G level. The electronic structure and its related properties, for example, relative stability, the charge transfer between the donor and accepter, and the change of geometric parameters of the complexes were investigated. The results show that the stability of the complexes is in the order of NH3>CH3NH2>(CH3)2NH> (CH3)3N. An obvious charge-transfer was observed in the process of forming the complexes. The stability of the series of complexes keeps a good linear relation to the CT amount, the energy gap L-H between LUMO and HOMO, and the distance of extended Hydrogen bond respectively . In addition, the stability is also related to the atomic net charges of the donor center and accepter center, etc. The stability of the complexes may be caused both hydrogen bond interaction and electrostatic interaction between the molecules. The calculation results might be better used to explain some experimental phenomena and regularities.Molecular simulation methods have been applied to characterization ofthe interaction between the complex Co[L]2Cl2[where L=2- (2',4'-Dichloro-phenoxymethyl)-1H-benzimidazole] and DNA[ ( GCGCTTAAGCGC) 2] in MM+ force field. Their interactions have been studied. The results show that: the intercalation on major groove is dominant.Based on the INDO/SCI method, the dipole moment u and the nonlinear second-order polarizability Bu of compounds 4-(1H-benzimidazole-3-ium-2-yl) benzoate(1), 2-ntro-1H-benzimidazole(2) and 4-(1H-Benzimidazol-2-yl) benzoic acid (3) were calculated by using of our program. The calculated results indicate that molecule 1 has higher second-order nonlinear optical polarizability. According to this studies, the second-order nonlinear optical properties of derivatives of molecule 1 were studied as well. The results show that: Those derivatives have higher values. Therefore they are good future materials of second-order nonlinear optics.A series of dithiocarbamate metal complexes have been synthesized and their crystal structures have been determined by X-ray single-crystal structure diffraction...