Synthesis and characterization of novel benzimidazole embedded 1,3,5-trisubstituted pyrazolines as antimicrobial agents

Efficient syntheses of some new substituted pyrazoline derivatives linked to substituted benzimidazole scaffold were performed by multistep reaction sequences. All the synthesized compounds were characterized using elemental analysis and spectral studies (IR, 1D/2D NMR techniques and mass spectrometry). The synthesized compounds were screened for their antimicrobial activity against selected Gram-positive and Gram-negative bacteria, and fungi strain. The compounds with halo substituted phenyl group at C5 of the 1-phenyl pyrazoline ring (15, 16 and 17) showed significant antibacterial activity. Among the screened compounds, 17 showed most potent inhibitory activity (MIC = 64 {\mu}g mL-1) against a bacterial strain. The tested compounds werefound to be almost inactive against the fungal strain C. albicans, apart from pyrazoline-1-carbothiomide 21, which was moderately active.