Sensitive water-soluble fluorescent chemosensor for chloride based on a bisquinolinium pyridine-dicarboxamide compound

摘要: Abstract The new fluorescent dicationic compound, N,N′-bis(N-benzyl quinolinium)pyridine-2,6-dicarboxamide triflate 1, was synthesized and studied as a chemosensor for inorganic anions in water. At pH 5.0 chloride quenches the blue fluorescence of 1 (the Stern–Volmer constant KSV = 380) forms very stable complex with receptor (KA = 5050 M−1). A photoinduced electron transfer quenching mechanism simultaneous receptor-chloride complexation both excited ground state is proposed. On basis 1H NMR UV–vis titrations, ESI-MS experiments, crystal structure DFT calculations, binding mode Cl− proposed involving two hydrogen bonding interactions N–H···Cl− formation short C–H···Cl− contacts inside cleft formed by pyridine-dicarboxamide motif; these are favored complementarity to anion. efficient attributed strong acidification NH CH donors quaternization quinolyl groups. allows detection water limit 33 μmol L−1 good selectivity over other common such bromide, phosphate, pyrophosphate acetate.