Abstract

Two bis urea based acyclic receptors (1 and 2) containing two pyridyl moieties with different spacers are synthesized. These receptors are further transformed to metallo-macrocyclic receptors (3 and 4) by coordinating with metal center through pyridine ring ‘N’. The binding-behavior as well as selectivity of the receptors towards anions upon metal coordinated cyclization is studied and the results are compared with parent acyclic receptors. Receptors 2 and 4 containing a naphthalene moiety as a spacer as well as a fluorophore behave as ‘on-off’ sensors towards anions.

Keywords: Anion recognition, fluorescence sensing, urea and acyclic receptors, fluorophore, 3-Aminopyridine, DMF, acetonitrile, FT-IR, HRMS, FAB, UV-vis titration, Fluorescence emission titration, Stern-Volmer plot, Fluorescence Quenching, DMSO, 13C NMR, 1,1'-(4,4'-methylenebis(4,1-phenylene))bis(3-(pyridin-3-yl)urea), 1,1'-(naphthalene-1,8-diyl)bis(3-(pyridin-3-yl)urea), 1,1'-(4,4'-methylenebis(4,1-phenylene))bis(3-(pyridin-3-yl)urea) palladium dichloride, 1,1'-(naphthalene-1,8-diyl)bis(3-(pyridin-3-yl)urea) palladium dichloride