Synthesis, Characterization and Antimicrobial Evaluation of some Schiff Bases Derived from Symmetrical 4-amino-1,2,4-triazole

A series of new Schiff bases, namely 4-(substituted benzylidene amino)-4H-1,2,4triazoles (5a-j) derivatives were synthesized by the reaction of symmetrical substituted 4amino-1,2,4-triazole (4) and appropriate substituted aromatic aldehydes in presence of acetic acid. The synthesized imines were characterized on the bases of their physical properties and spectroscopic data. Some of these compounds were tested for biological activities as antibacterial and antifungal agents and showed a significance to moderate activity.

In view of these facts and as a continuation of our search for new biological agents, in this paper we report, the synthesis of new Schiff bases by the reaction of new 4-amino-3,5bis(diphenyl hydroxymethyl)-1,2,4-triazole with different aromatic aldehydes in hot acetic acid.Some of theme were evalutated for their biological activities.

EXPERIMENTAL
Melting points were measured on an electro thermal 9300 melting point apparatus and are uncorrected.IR spectra were recorded on a Bruker optics (FT-IR) spectrophotometer Co. using KBr-disk. 1H-NMR and 13 C-NMR spectra were recorded on Bruker 300-MHz spectrometer (University of Al Al-Bait Jordan) using TMS as an internal standard and DMSO-d 6 as a solvent.UV spectra were recorded by Shimadzu UV-Visible recording UV-160 spectrophotometer.The methyl benzilate (2) (m.p.76˚C) and benzilic acid hydrazide (3) (m.p.166-167˚C) were prepared by (Mohammed, 2000).The theoretical calculation and three dimensional (3D) configurations were achived out using (Chem Office Program, Version 8.0.3 September 24, 2003 MOPAC/MM2.For determination of the preliminary biological activities the disc diffusion method was used (Bauer et al.,1966;Lu et al., 2005).
Disc diffusion method (sensitivity test) was adopted for this study following the published procedure.It is worth mentioning that the incubation time for bacterial activity test was 24 hrs., while the antifungal test was 14 days.The results of these studies are tabulated in Tables (4) and (5).

Antibacterial and antifungal studies
All the synthesized compounds were screened for in vitro antibacterial and antifungal activity by adopting the disc diffusion method.For antibacterial studies the microorganisms employed were Esherichia coli, Staphylococcus aurous, Micrococcus, Pseudomonas, Bacillius 11 and Bacillius 12.While for antifungal, Microsporumgypseum, Microsporumdestortum, and Trichophytonrubrum were used as microorganisms.Both antimicrobial studies were assessed by a minimum inhibitory concentration.The results are summarized in Tables (4 and 5).
From the obtained data, it is evident that compounds (5a and 5d) possess a very good activity against bacteria Strains like E. coli and Staphylococcus.And the compounds (5h, 5i and 5j) possess almost a significant activity against all fungi tested at 1 mg/ml and 2 mg/ml.The remaining compounds showed a moderate activity against other bacteria and fungi tested.