SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL EVALUATION OF SCHIFF’S BASE AND ARYL AMINOMETHYL DERIVATIVES.

. Schiff’s bases are obtained on heating an aldehydes with aromatic amine in presence of glacial acetic acid. These are the compounds containing characteristic –HC=N– group. Aryl amino methyl derivatives of heterocyclic compounds to synthesize by selective reduction of schiff’s bases (imine group) with sodiumborohydride in controlled experimental condition. Schiff’s base of N-Aryl-1-[6-methyl-2-(4-methylphenyl)imidazo[1,2- a ]pyridin-3-yl]methanimines & Aryl amines of N-Aryl-1-[6-methyl-2-(4-methylphenyl)imidazo[1,2- a ]pyridin-3-yl]methanamines were prepared. Their chemical structures were confirmed by means of IR, NMR, Mass data and by elemental analysis. All of the synthesized compounds were tested for their antibacterial and antifungal activity.

The structure of synthesized compounds were assigned based on Elemental analysis, I.R. 1 H-NMR and Mass spectral data. The antimicrobial activity was assayed by using the cup-plate agar diffusion method 14 by measuring the zone of inhibition in mm. All the compounds were screened in vitro for their antimicrobial activities 15 against varieties of bacterial strains such Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Fungi Aspergillus niger using Dimethylformamide solvent at 40 µg/ml concentration. Standard drugs like Amoxicillin, Benzyl penicillin, Ciprofloxacin, Erythromycin and Griseofulvin were used for comparison purpose. (Table-1).
The formulas of the selected compounds were confirmed by the elemental analysis and their structures were determined by IR , 1 H-NMR , and mass spectral data.

ANTIFUNGAL ACTIVITY:
The antifungal data revealed that compounds were least toxic to the fungal strain. However mild activity was shown by the compounds (1c),(1d),(1j),(2c),(2g),(2h), against A. niger. The antibacterial activity was compared with standard drug viz. Amoxicillin, Benzyl Penicillin, Ciprofloxacin, Erythromycin and antifungal activity was compared with standard drug viz. Griseofulvin.

EXPERIMENTAL SECTION:
Melting points were taken in open capillary tubes are uncorrected. IR spectra (cm -1 ) were recorded on Shimadzu-435-IR Spectrophotometer and, 1 H-NMR spectra on Bruker spectrometer(300MHz) using TMS as an internal standard, chemical shift in δ ppm.

General procedure for the preparation of 2-(4-Methylephenyl)imidazo[1,2-a]pyridin-3carbaldehyde (Type-I):
Align 2.0 lit 4/N RBF equipped with over head stirrer with condenser on water bath. Charged 84 ml DMF and 1.0 lit CHCl 3 into RBF. It was cooled at 0 -5 o C temperature. Slowly added 165 ml POCl 3 within 1.0 h. During addition the exothermicity was controlled. Temperature raised at 10-15 o C and stirred for 30 minutes. 50g (0.225 mol) of 6-Methyl-2-(4methylphenyl)imidazo[1,2-a]pyridine was added slowly, temp. raises, refluxed for 6 hrs. CHCl 3 was removed by vacuum distillation and reaction mass cooled at room temperature, poured into 2.0 lit ice cold water. Neutral pH adjusted bellow room temperature with the help of mild coustic solution. The solid mass was collected by filtration, washed with water, dried and crystallized from the methanol. Yield 80%, m.p. 152 o C.

CONCLUSION
The present study leads to a convenient synthetic method for the synthesis of new compounds. Which show significant antibacterial and antifungal activity. Further investigation with appropriate structural modification of the above compounds may result in therapeutically useful products.