Synthesis of polyquinoline ether and its optical sensor property in the presence of metal cations

Semirigid polyquinoline with a flexible ether linkage was prepared via Friedlander quinoline synthesis, of which monomer was obtained through a five-step synthesis. We investigated the polymer as a fluorescent sensor toward ferric ion that used a quinoline unit as a fluoroionophore group. The polymer solution in dimethylformamide/tetrahydrofuran showed the hyperchromic shift of the absorption maximum upon addition of metal ions exhibiting that the effect was clearly manifested upon exposure to ferric ion. A fluorescence quenching was observed in the presence of ferric ion corresponding to an interaction of the ferric cation to the polyquinoline ether, which results in a photoinduced electron-transfer quenching pathway showing a Stern-Volmer constant (KSV) of 7.17 ?? 103 (M-1).close171