Ab initio Molecular Orbital Study of Emission Mechanism of 2, 6-Bis(quinolinecarboxy)methylpyridine as Fluorescent Chemosensors for Zinc and Cadmium Ions

Abstract

2, 6-Bis(quinolinecarboxy)methylpyridine (P2Q) was synthesized as fluorescent chemosensors for metal ions. P2Q hardly shows fluorescence itself, but it showed strong fluorescence with the addition of zinc or cadmium ions (I_{f, Zn} > I_{f, Cd}). Therefore, the Ab initio molecular orbital calculations (Gaussian 98) using the time-dependent density functional method with 6-31+G(d) basis set were carried out for a quinoline chromophore of P2Q and its metal complexes to investigate the emission mechanisms. The results of the molecular orbital calculations suggest that the lowest luminescent state has changed from the nπ* to the ππ* by coordinating with a metal ion.