Synthesis and photo-physical characteristics of ESIPT inspired 2-substituted benzimidazole, benzoxazole and benzothiazole fluorescent derivatives.

Novel 2-(1H-benzimidazol-2-yl)-5-(N,N-diethylamino) phenol, 2-(1,3-benzoxazol-2-yl)-5-(N,N-diethylamino) phenol, 2-(1,3-benzothiazol-2-yl)-5-(N,N-diethylamino) phenol and their derivatives have been synthesized from p-N,N-diethyl amino salicylaldehyde with different substituted o-phenylenediamine or o-aminophenol or o-aminothiophenol and their photo-physical properties were studied. Effects of solvent polarity in the absorption-emission properties of synthesized compounds were investigated. All these compounds shows excited state intra-molecular proton transfer pathway having single absorption and dual emission characteristics. The fluorescent compounds were characterised by FT-IR, (1)HNMR, (13)C NMR and Mass spectral analysis. TGA analysis showed these compounds are thermally stable up to 200 °C.