10.22376/ijpbs.2019.10.1.p1-12 Volume 7 Issue 1 2016 (January - March) In view of developing novel and effective antimicrobial agents, novel series of pyrazolines (4a-g and 5a-g) bearing 2,3,4-trichlorophenyl moiety were synthesized by treating 1-(2,3,4-trichlorophenyl)-3-(4-aryl)-2-propene-1-ones (3) with hydrazine hydrate and formic acid/ acetic acid (Schemes 1 and 2). The newly synthesized compounds were characterized by elemental analysis and spectroscopic studies and screened for their lessThan i greaterThan in vitro lessThan /i greaterThan antibacterial and antifungal activities. The screening studies revealed that the novel pyrazoline derivatives (4a-g and 5a-g) exhibited moderate to good activity. LAXMANA K, SURESH P. NAYAK, JAGADEESH PRASAD D, PRAKASH ANIL CASTELINO, KUMARA CHALUVAIAH AND SUCHETHA KUMARI Formylpyrazoline, Acetylpyrazoline, Antimicrobial Activity, Spectroscopic Data. 32-39