Architecture of dipodal ratiometric motif showing discrete nanomolar response towards fluoride ion

Abstract

A new fluoride selective fluorescent receptor (13E,19E)-N1′,N3′-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide (1) was designed and synthesized. Receptor 1 showed a highly selective fluorescent ‘turn-on’ response towards F− among the various tested anions such as F−, Cl−, Br−, I−, HSO4−, H2PO4−, NO2− and CN− in CH3OH:H2O (50:50, v/v), due to the formation of hydrogen bonding host–guest complex in 1:1 stoichiometry with a detection limit of 45.7 nM and association constant of 1.0 × 104 M−1. The nature of interactions between the receptor 1 and F− was investigated by 1H NMR and the probable structure of the 1·F− complex was predicted by B3LYP/6-31G** method.