Photoenolization via excited state proton transfer and ion sensing studies of hydroxy imidazole derivatives

A light stimulated photo-enolization in hydroxy imidazole systems (o-hydroxynaphthyl phenanthroimidazole, 3 and o-hydroxyphenyl phenanthroimidazole, 4) by excited state proton transfer induces turn Off' fluorescence and ratiometric changes in the absorption spectrum. Benzyl phenanthroimidazole (5) does not exhibit the photo-enolization due to absence of o-hydroxyl group. Solvatochromism, time resolved photoluminescence measurement and ionic interactions studies of 3-5 are examined in semi-aqueous medium through UV-vis and fluorescence spectroscopy. Fluorescent probe 3 exhibits fluorescence turn Off and turn On responses with acetate ions in semi-aqueous medium by tuning the excitation wavelength. (C) 2016 Elsevier B.V. All rights reserved.