A new D-π-A type intramolecular charge transfer Dyad System to detect F-: Anion induced CO2 sensing

A new D-pi-A type intramolecular charge transfer (ICT) based fluorescence probe have been designed and synthesized by appending imidazole (donor, D) and benzothiazole (acceptor, A) moieties through a thiophene bridge. The molecular probe upon interaction with different class of anions showed fluorescence turn-on behavior to detect fluoride anion (F-) selectively, in acetonitrile. Jobs plot analysis revealed a 1:1 binding stoichiometry between probe and F- with high binding constant and detection sensitivity(51 nM; 0.092 ppb). Moreover, upon interaction of 1 + F- with CO2 the original chromo and fluorogenic behavior of the probe was revived. The change in photophysical behavior and NMR spectroscopic studies suggested about the On-Off-On type of fluorescence sensing mechanism, involving deprotonation of -NH fragment of imidazolyl unit in the presence of F-. (C) 2016 Elsevier B.V. All rights reserved.