Synthesis and characterization of molecules containing thiazole and oxazole moieties and study of ESIPT phenomenon

Two novel ESIPT molecules, 2-[4-(1,3-benzothiazol-2-yl)naphtho[1,2-d][1,3] oxazol-2-yl]phenol 9a and 4-[4-(1,3-benzothiazol-2-yl)naphtho[1,2-d][1,3]oxazol- 2-yl]benzene-1,3-diol 9b were synthesized by condensing 1-amino-3-(1,3- benzothiazol-2-yl)naphthalen-2-ol with 2-hydroxybenzoic acid and 2,4-dihydroxybenzoic acid respectively. The novel compounds were characterized by FT-IR, ¹H NMR, Mass spectral and elemental analysis. Effect of polarity on photo physical properties, absorption and emission were studied. Compounds showed single absorption and dual emission due to ESIPT phenomenon. The structural changes due to ESIPT phenomenon in terms of bond angle, bond distances and geometry were investigated by using Gaussian 03 software. These two novel ESIPT molecules are thermally stable up to 200 °C.