Synthesis, Application Of The Asymmetrical Di-Schiff Bases

Schiff base compounds have become a hot spot for a long time due to the funtionality of C=N and the electron effect , and this led to their widespread app1ications in medicine, catalysis, chemical analysis and so on. While, because of special structure, the asymmetrical dischiff bases could be used to some different areas, such as oxygen molecule carrier,catalyst,pesticides,antibacterial agents,the simulation molecules of biological process and so on. So the studies of synthesis and properties for the compund also have become a quite active subject in chemistry fields in recent decades.The synthesis and exploratory development of schiff bases were summarized in this paper and their synthesis, character, crystal structure, antibacterial activity were also investigated, especially the asymmetrical dischiff bases. First of all, with raw materials of differently substituted benzoic acid, the actions are followed by acylation, esterification, fries rearrangement, condensation and so on. The mono-schiff base reacted with ten kinds of aldehydes, such as salicylaldehyde, p-dimethyl aminobenzaldehyde, 2-thiophenecarboxaldehyde, benzaldehyde, 2-furaldehyde, n-valeraldehyde, cinnamic aldehyde, ferula aldehyde, 2-chlorbenzaldehyde, 4-hydroxyl benzaldehyde in different conditions. Thereby forty-six asymmetrical dischiff bases and three mono-schiff bases were given. The single-crystal of new products was developed by slow evaporation of solvent. Only one compound gave single-crystal which was analyzed by X diffractometer. Structures of products were characterized by NMR, TLC, X-ray, melting point.The study on antibaterial activity of the asymmetrical dischiff bases which are about forty-six was carried out by filter paper method. Two representative strains, Gram-negative bacterium (E. coli) and Gram- positive bacterium (S. aureus) were selected. Their antimicrobial activity was determined by measurement for zone of inhibition. It was detected in multiple controlled trials that the antibacterial property of compunds were determined according to the size of zone of inhibition. Results showed that some compounds have the activity of inhibiting the growth of Gram- positive bacterium (S. aureus), and there is no use to Gram-negative bacterium (E. coli).