Synthesis and antimicrobial activities of Schiff bases derived from 5-chloro-salicylaldehyde.

A series of Schiff bases (compounds 1-26) were synthesized by reacting 5-chloro-salicylaldehyde and primary amines, 15 (compounds 2-4, 6, 7, 10, 12-17, 23, 25 and 26) of which were first reported. The chemical structures of these compounds were confirmed by means of (1)H NMR, (13)C NMR, ESI-MS and elemental analyses. The compounds were assayed for antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger, Candida albicans and Trichophyton rubrum) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trtrazolium bromide) method. Among the compounds tested, (E)-4-chloro-2-((4-fluorobenzylimino)methyl)phenol (2) showed the most favorable antimicrobial activity with MICs of 45.2, 1.6, 2.8, 3.4, and 47.5 microg/mL against B. subtilis, E. coli, P. fluorescence, S. aureus and A. niger, respectively.