Synthesis,Characterization And Spectroscopic Properties Of N-heterocyclic Ligands And Zinc(Ⅱ), Copper(Ⅱ), Cobalt(Ⅱ) Schiff Base Complexes

Schiff base complexes are a class of important compounds that exhibit attractive properties as well as diverse structures.Such organic molecules are widely used in catalysis,chemical sensing,bioimaging,organic light-emitting diode（OLED）,dye-sensitized solar cell（DSSC）,medicine,pesticide,as well as in non-linear optics for data storage,processing,telecom and optical switching have potential performance.In addition,nitrogen heterocyclic ligands have the characteristics of aromaticity,relatively stable structure,unique biological activity,low toxicity,etc.The synthesis and biological applications of these compounds are increasing.Therefore,the design and synthesis of nitrogen heterocyclic ligands and new schiff base complexes are very worthy of further study.In this thesis,five kinds of nitrogen heterocyclic ligands containing quinazoline ring were synthesized using oxime,which an important organic reaction intermediate.They were synthesized by o-acetophenone oxime and 4-nitrobenzaldehyde,4-chlorobenzaldehyde,4-cyanobenzaldehyde,4-imidazole formaldehyde,3-ethoxy salicylaldehyde,respectively:HL₁:4-methyl-2-（4-nitrophenyl）-1,2-dihydroquinazoline 3-oxide;HL₂:2-（4-cyanophenyl）-4-methyl-1,2-dihydroquinazoline 3-oxide;HL₃:2-（2,4-dichlorophenyl）-4-methyl-1,2-dihydroquinazoline 3-oxide;HL₄:2-（4-imidazolyl）-4-methyl-1,2-quinazoline-N³-oxide;HL₅:2-（3-ethoxy-4-phenolic hydroxy）-4-methyl-1,2-quinazoline-N³-oxide.Then,the ligands structure were determined by elemental analysis,¹H NMR and other basic characterization methods.The ligand HL₁、HL₂ as primary ligand and 1,10-phenanthroline（phen）as secondary ligand react with Zn（NO₃）₂?6H₂O,respectively.The single crystals of metal complexes were obtained by natural evaporation method.Afterwards,the chemical constitution,structure parameters and space structures were determined by X-ray single crystal diffractometer（XRD）.Two mononuclear Zn（Ⅱ）complexes 1 and 2 display similar coordination geometry and crystallize in the triclinic system with P-1 space group,nitrate ions participate in the coordination and form a distorted trigonal bipyramid coordination environment.The Zn（Ⅱ）complex 3 is a Zn1（Ⅱ）,Zn2（Ⅱ）-centered distorted octahedral configuration.By the ligands HL₄ with Cu（NO₃）₂·3H₂O and Co（NO₃）₂·6H₂O of coordination reaction,synthesis two kind of Cu（Ⅱ）and Co（Ⅱ）complexes 4 and 5,in which the complexes crystal are six coordination geometry are octahedral.The coordination configurations of the metal ions in the above five complexes and the supramolecular forces in the crystal were analyzed and their supramolecular structures were determined.Based on the complexes obtained,the M（Ⅱ）complexes were analyzed using IR and UV–Vis spectroscopy,elemental analysis and single-crystal X-ray crystallography.The spectroscopic data of the M（Ⅱ）complexes were compared with the ligand.Moreover,the electrochemical properties of Cu（Ⅱ）and Co（Ⅱ）complexes have been studied by cyclic voltammetry.Moreover,thermal property of Co（Ⅱ）complex was also studied.In addition,the antibacterial activity of the ligands and complexes against Gram-positive bacteria（Staphylococcus aureus）and Gram-negative bacteria（Escherichia coli）was determined by measuring the size of the inhibition zone by punch method.