In the present study, a series of substituted (E)-N-benzylidene-2-aminopyrimidine compounds have been synthesized by condensation reaction with 2-aminopyrimidine and meta- and para- substituted benzaldehydes. These synthesized Schiff’s base compounds are confirmed by their physical constants, UV, IR and NMR spectral data. All the observed UV absorption maximum λmax(nm), IR frequencies νC=N(cm-1), NMR δ(ppm) of C-H & C=N chemical shifts have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analyses in order to study the effect of substituents on these spectral data has been studied. The antimicrobial activities of all the synthesized Schiff’s base compounds have been studied using Bauer-Kirby disc diffusion method

In the present study, a series of nine number of (E)-1-benzylidene-2-(4-chlorophenyl) hydrazine compounds have been synthesized by condensation reaction of meta and para substituted benzaldehydes with 4-chlorophenylhydrazine using acetic acid catalyst. They are characterized by their physical constants, UV (200-450 nm), Infra-Red (KBr, 4000-400 cm−1) and NMR (1H and 13C) spectral data. The observed UV, IR and NMR spectral data have been correlated with Hammett substituent constants and Swain-Lupton’s F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis the effects of substituents on the spectral data have been discussed. The antimicrobial activities of all the synthesized (E)-1-benzylidene-2-(4-chlorophenyl) hydrazine compounds have been studied using Bauer–Kirby method.

In the present investigation, a series of substituted (E)-1-(4-fluoro-3-methylphenyl)-3-phenylprop-2-en-1-one compounds were synthesized by condensation reaction of 4-fluoro-3-methyl acetophenone with substituted benzaldehydes in the presence of alkali. The yields of synthesized compounds are more than 80%. The structures of all the synthesized compounds were confirmed by their physical constants, UV, IR and NMR spectral data. All the observed spectral data of substituted (E)-1-(4-fluoro-3-methylphenyl)-3-phenylprop-2-en-1-one compounds have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analyses. From the results of statistical analysis the effects of substituents have been discussed.

A series of substituted (E)-2-benzylidenehydrazinecarbothioamide compounds were synthesized by condensation of thiosemicarbazide with substituted benzaldehydes. The synthesized substituted (E)-2-benzylidenehydrazinecarbothioamide compounds were characterized by their physical constants, UV, IR and NMR spectra. The antimicrobial activities of these synthesized substituted (E)-2-benzylidenehydrazinecarbothioamide compounds have been screened by Bauer-Kirby method using human pathogenic bacteria and fungal species. The antimicrobial activities of all synthesized (E)-2-benzylidenehydrazinecarbothioamide compounds have shown significant activity.