Study Of Ground State Structure And Excited-State Structural Dynamics Of Amine And Aminocarboxy Copper Complexes

Transition metal complexes are an important part of the chemical and biological active centers of natural metalloenzymes.In organism or in aqueous solution,the structures,properties and states of transition metal complexes will be affected by various weak interactions in natural metalloenzymes,such as hydrogen bonding,ionization and hydrophobic interaction.The structural study of transition metal complexes can lay the foundation for insight into the complicated biological activities of natural metalloenzymes in aqueous solution.Copper-aminocarboxy complexes are an important model molecules,which have been widely reported as for artificial metalloenzymes.However,for which the various weak interactions exist in metal complexes,most of the synthesized complexes cannot reflect the catalytic properties of the corresponding metalloenzymes.In addition,there are few studies on the excited state structure dynamics of the metal complexes.In this thesis,the ground structure and excited state structural dynamics of copper-1,2-cyclohexanediamine and histidine complexes are investigated by means of resonance Raman spectroscopy,which is a powerful means of structural characterization and excited state dynamics.Results are as follows:（1）The complexes of 1,2-cyclohexanediamine and histidine copper chloride were prepared.The crystal structure of the complex was characterized by Fourier transform infrared（FT-IR）spectrum and laser microscopic Raman（Micro-Ra）spectrum.The optimized structure,stabilization energy and Gibbs free energy of a series of possible intermediates and products were obtained in aqueous solution.The hydrogen bond and charge balance interaction of Cl^-ions in the formation of the crystal structure was investigated.The time-dependent density functional theory（TD-B3LYP）was used to calculate the electronic transition energy and transition orbital information of the complex.（2）In crystal,the repeating unit of the complex is[Cu（Dach）₂H₂O]Cl₂,Cu（II）coordinated with four N atoms in two 1,2-diaminocyclohexane molecules to form a Cu N₄ planar tetragonal structure,and H₂O involved in axial coordination,while the two external equilibrium ions Cl^-form N-H?Cl bridging hydrogen bonded with two NH₂ groups,and which played an important role in the formation of[Cu（Dach）₂H₂O]Cl₂ complex.The main structures of the complex were[Cu（Dach）₂H₂O]²⁺and[Cu（Dach）₂Cl]⁺in aqueous solution.According to the analysis of stabilization energy,the main coordination reactions of the crystal precipitation were[Cu（Dach）₂H₂O]²⁺+2Cl^-?[Cu（Dach）₂H₂O]Cl₂and[Cu（Dach）₂Cl]⁺+H₂O+Cl^-?[Cu（Dach）₂H₂O]Cl₂.（3）In aqueous solution,copper-1,2-diaminocyclohexane complex had a strong absorption band A.The A-band were designated as ligand to metal electronic transition ofσ（L）→d_xy（M）.The resonance Raman spectrum of the complex in aqueous solution was designated as Cu-N stretching vibration,Cu-N-C/H-N-H/N-C-C bending vibration,in which the Cu-N and N-C-C vibration modes dominated the resonance Raman.In Franck-Condon region,the initial reaction coordinates of the A-band was mostly along the Cu-N stretching vibration progression.（4）In aqueous solution,the complex b2[Cu[H(N_am,O_oc),(N_am,N_im,O_oc)]]⁺and c8[Cu(H(N_am,O_oc),(N_am,N_im,HO_oc))]²⁺were the main ions of histidine-copper complex.The UV spectrum was obtained in aqueous solution,which two absorption bands A and B were found.The electronic transition information of complexes b2 and c8 about the two absorption bands could be histidine to copper charge-transferσ（L）→d_xy（M）transition.The excited state dynamics of histidine copper complex was multidimensional.The initial reaction kinetic coordinates were mainly along Cu-O_OCstretching vibration,O=C=O/C-O-Cu bending vibration.The initial reaction kinetic coordinates of B-band were mainly along Cu-N_an/Cu-N_imstretching vibration,=N-C-C/=N-C-N bending vibration and C=C stretching vibration modes expansion.