Synthesis And Biological Activities Of Schiff Bases And Their Cu,Mn Complexes Constructed Through Derivatives Of Salicylaldehydes

Schiff base constructed through derivatives of salicylaldehyde and their metal complexes have become the hotspot in recent years due to their biological activities,such as antimicrobial and antitumor. The thesis designes two series of structual Schiff base. One series is the Schiff base constructed through derivatives of salicylaldehydes and amino acids, the other is the Schiff base constructed through derivatives of salicylaldehydes and thiosemicarbazone,as well as coordination compounds of their Cu(II),Mn(II) complexes have been synthesized.Their biological activitives were stuied simply.It provides important experimental data for searching antibactericial and antitumor agents with high-effective and low-adverse.In this thesis, salicylaldehyde was the starting material. At first, five derivatives of salicylaldehyde were synthesized. The single crystals of 3-nitrosalicylaldehyde and sodium salicylaldehyde-5-sulphonate were obtained by the method of solvent evaporation and solvothermal, and their crystal datas were determined by X-ray diffraction. L-methionine, L-tryptophan and thiosemicarbazide were selected as primary amines. Twelve new Schiff bases were synthesized, including 3,5-diiodosalicylaldehyde thiosemicarbazone(HL₁), 3-nitrosalicylaldehyde thiosemicarbazone(HL₂), sodium salicylaldehyde-5-sulphonate thiose- micarbazone(HL₃), sodium 3,5-dibromosalicylaldehyde-(L-methioninate)(HL₄), sodium 3-nitrosalicylaldehyde-(L-methioninate)(HL₅),sodium5-nitrosalicylaldehyde-(L-methioninate)(HL₆),sodium 3,5 -diiodosalicylaldehyde-(L-methioninate)(HL₇), sodium (sodium salicylalde- hyde-5- sulphonate)-(L-methioninate) (HL₈), sodium 3,5-dibromosalicylaldehyde-(L-trypto- phanate) (HL_<sub>9), sodium 3,5-diiodosalicylaldehyde-(L-tryptophanate) (HL₁₀), sodium 3-nitro salicylaldehyde-(L-tryptophanate)(HL₁₁)), sodium 5-nitrosalicylaldehyde-(L-tryptophanate) (HL₁₂). All the Schiff bases were characterized and confirmed by melting point, elementary analysis, IR spectra, UV spectra and HNMR analysis. The single crystals of 3-nitro salicylaldehyde thiosemicarbazone were cultured by solvent evaporation method, and its crystal datas were determined by X-ray diffraction. As well as 24 complexes of transition metal with the purified ligands have been synthesized. The complexes were characterized by IR spectra, UV spectra, TG- DTA analysis and molar conductance analysis. The possible structures and chemical formulae of the complexes were proposed based on these characterizations.The conjugation between bovine serum albumin(BSA) and eight complexes was investigated by using fluorescence spectra,ultraviolet spectra.The metal complexes can reduce the fluorescence intensity of bovine serum albumin.According to the theories of fluorescence quenching, the way of fluorescence quenching was static quenching. The binding diatance r , binding constants KA and binding sites n of these complexes and BSA were calculated respectively, and the average number of binding sites n was about 1.Ligands could not quench the fluorescence of BSA. The conjugation between [HL₃-Cu(II)] and BSA is the weakest.The concentration of the free complex was increased in the vivo and the effects was strongthen.The antibacterial activities of HL₂,HL₇,HL₉ and their Cu(II),Mn(II) complexes have been primarily studied against S.aureus and E.coli. The diameters of antibacterial inhibition zone of different concentration were measured by using disc diffusion assay method. The result indicates that both Schiff base and their complexes have antibacterial ability to the bacteria tested and the complexes have the higher activity than the ligand. There is no linear correlation between antibacterial effect and concentration.