Alteration in metal ion induced fluorescence signaling responses of benzofurazan appended acyclic amino-receptor through its structural modification

Abstract

Fluorescent signaling probes 3 and 4 in the integrated 'fluorophore-receptor' format have been synthesized by derivatization of 'amino-alkyl-amino' based receptors with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole fluorophore for metal ion induced fluorescence recovery through perturbation of charge-transfer character of fluorophoric D(donor)-pi-A(acceptor) segment. Among all the metal ions investigated, the 'amino-ethyl-amino' receptor based probe 3 exhibits fluorescence enhancement selectively in presence of Zn(II) ion, while the probe 4 with an structurally modified 'amino-ethyl-oxy-(phenyl methyl)-amino' based receptor exhibits fluorescence enhancement with Co(II), Ni(II), Cu(II), Zn(II), and Ag(I). The chemo-selectivity of 3 towards Zn(II) ion fails in 4 due to a structural modification to receptor's framework. (C) 2011 Elsevier B.V. All rights reserved.