Synthesis and characterisations of some new 2,4-dihydro-[1,2,4]-triazol-3-one derivatives and X-ray crystal structures of 4-(3-phenylallylideneamino)-5- thiophen-2-yl-methyl-2,4-dihydro-[1,2,4]triazol-3-one

Compounds 2 were synthesised via the reaction of 4-amino-5-thiophen-2-yl-methyl-2,4-dihydro- [1,2,4]- triazol-3-one (1) with aldehydes. Compounds 3 and 4 were obtained from compounds 2 with bromo acetophenone and ethyl bromoacetate, respectively. The synthesis of compounds 2, 3, and 4 and crystal structure of compound 2a are being reported. The molecular structures were identified by IR, 1 H- NMR, 13C-NMR, MS, and elemental analyses. Compound 2a crystallises in the monoclinic P 21 /n space group, with a = 6.565(5) ˚A, b = 18.278(5) ˚A, c = 13.8166(18) ˚A, β = 96.227(5)° , V = 1553.6(14) ˚A^3, Z = 4. The newly compounds synthesised were screened for their antibacterial and antifungal properties. Among the compounds, 4d showed antimicrobial activity against Candida albicans ATCC 60193 and Candida tropicalis ATCC 13803.