Syntheses, Characterization and Biological Evaluation of Some New (2E)-1-(4'-bromophenyl)-3-(4-(diphenylamino)phenyl)prop-2-en-1-one Chalcones and their analogues

Eight novel triphenylamine chalcones with different substitution patterns were successfully synthesized using the conventional Claisen-Schmidt condensation reaction in basic medium at room temperature, and purified by recrystallization method using ethanol, the percentage yield of the compounds were between 30 – 92 %. The synthesis of the target chalcones involves a nucleophilic enolate attack on the electrophilic carbonyl carbon of 4-(Diphenylamino) benzaldehyde resulting in the formation of a new carbon-carbon bond. The triphenylamine chalcones were characterized by means of FT-IR and NMR spectroscopic analyses. The antimicrobial screening against different pathogens revealed that, all synthesized compounds showed marked activity against the tested microbe. (E)-3-(4-(diphenylamino)phenyl)-1-(3'-nitrophenyl)prop-2-en-1-one (1b) showed the highest zone of inhibition against Aspergillus niger, measuring 30 mm. The minimum inhibitory concentration (MIC) results revealed that, (E)-1-(4'-bromophenyl)-3-(4-(diphenylamino)phenyl)prop-2-en-1-one (1a), (E)-3-(4-(diphenylamino)phenyl)-1-(3'-nitrophenyl)prop-2-en-1-one (1b), (E)-1-(4'-chlorophenyl)-3-(4-diphenylamino)phenyl)prop-2-en-1-one (1c), (E)-3-(4-diphenylamino)phenyl)-1-(4'-fluorophenyl)prop-2-en-1-one (1d) and (E)-4-(3-(diphenylamino)phenyl)-1-(4-fluorophenyl)-2-methylbut-3-en-1-one (2d) had the lowest MIC and inhibit Aspergillus niger growth at 12.5 µg/ml. All the synthesized compounds showed an MBC/MFC effect against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans and Aspergillus niger at 50 µg/ml.