Study On Magnetic And Biological Activity Of Pyrazolyl Pyridine Compounds

In recent years, pyrazol and pyridine compounds have become a hot research topic,not only in experimental synthesis but also in theory. Due to the unique nature of pyrazol, pyridine and their derivatives, which makes the complexes synthesized have a wide range of applications in magnetic materials and biological activities.This thesis is idivided into four chapters:（1） We selected pyridine-2,5-dicarboxylic acid and 2,2’-dipyridine as ligands which reacted with cadmium dinitrate, the pyridine bridged metal cadmium complex Cd₂（2,2’-bpy）₂（2,5-pdc）₂（NO₃）₂（H₂O）₂（1） was obtained, and IR spectrum, the herbicidal and fungicidal activities were tested. The results showed that the biological activity of the complex was low, and the preparation method of the compound was further improved.（2） We choosed single density functional method to calculate three pyridine organic bridging metal nickel complexes [Ni₂（μ-O₂P（H）Mes）₂（bpy）₄]Br₂（2）,[Ni₂（μ-O₂P（H）Ant）₂（bpy）₄]Br₂（3） and [Ni₂（μ-O₂P（H）Ph）₂（bpy）₄]Br₂（4）（Mes=2,4,6-trim ethylphen-yl, Ant=9-anthryl, Ph=benzol, bpy=2,2’-bipyridine） with density functional theory（DFT） combined with broken symmetry approach（BS）, calculation of magnetic coupling constant J, orbital energy and spin density. The results showed that complex 2showed weak antiferromagnetic, complex 3 has more strong antiferromagnetic than 2,complex 4 has ferromagnetic. Analysis of orbital energy shows that small energy splitting is the reason complex 2 has a weak antiferromagnetic, large the energy splitting is the reason complex 3 has more strong antiferromagnetic than 2, energy degeneracy is the reason complex 4 has ferromagnetic. Correlation analysis of magnetic structure shows that the dihedral angle of the order is 4 < 2 < 3, with a decrease of dihedral angle,complexes transition from antiferromagnetic to ferromagnetic, through the study of electrostatic charge the distribution and Molecular Frontier orbit system（HOMO and LOMO）, we determine the active site located on the N atoms of 2,2’- bipyridine ligands.（3） We choosed the hybrid density functional method to calculate a pyrazole bridged copper complex [Cu₂（L）]·3H₂O（5）（L=5-（（E）-1-（3-（（E）-1-（5-carboxy-4-methl-4,5-dihydro-1H-pyrazol-3-yl）ethylideneamino）propylimino）ethyl）-4-methyl-1H-pyrazol-3-carboxy） with DFT combined with BS to explain the reasons of the complex with magnetic and biological activity in theory. The results show that the calculated J value is-186.64cm-1 in the b3lyp/Lanl2 dz condition which is in accord with the experimental result. And further on the molecular orbital, orbital energy and spin density analysis, the results show that the magnetic properties of the complex system are affected by the orbital overlap, the energy splitting and the spin off field effect and the study of static charge analysis and frontier molecular orbital determined that the active site of the complex is mainly located in N atom of the pyrazole liagnd, which provides a theoretical basis for the further synthesis of molecular magnetic materials and biological active materials.（4） We choosed the mixed basis set to calculate an acetamide bridged metal copper complex {Cu₂（μ2-O₂CCH₃）₄}（OCNH₂CH₃）₂（6） with DFT combined with BS to explain the reasons of the complex with magnetic and biological activity in theory. The results show that the most suitable method is PBE, and the most suitable basis set is6-31G/SVP, which shows that the theoretical calculation of molecular system is dependent on both the method and the basis set. And further on the molecular orbital,orbital energy and spin density analysis, the results show that the magnetic properties of the complex 6 are affected by the orbital overlap, the energy splitting and the spin off field effect. The study of static charge analysis and frontier molecular orbital determined that the active site of complex 6 is mainly located in O atoms of the acetate liagnd,which provides a theoretical basis for the further synthesis of molecular magnetic materials and biological active materials.