Strong fluorescence of a complex based on 2,2-dipyridyl derivative----An experimental and theoretical investigation

Abstract

The metal-organic hybrid complex HgI2L (L = 4’-{4-[4-(N,N-dipropylamino)styryl]phenyl}6-phenyl-2,2′-bipyridine) was synthesized by coordination of L with HgI2. The crystals of HgI2L were obtained by self-assemble of HgI2 with L under ambient conditions, and its structure has been solved by single crystal X-ray diffraction. The fluorescence emission spectrum experiment shows that the complex has remarkable strong one and two-photon excited fluorescence. To clarify the mechanism of strong fluorescence properties, the natural transition orbitals (NTOs) and hole-electron transition analysis ground on the computational results under state specific PCM/TD-CAM-B3LYP method was performed. The results illustrate that, there is high similarity between the electronic structures and geometries of the optimized S0 and S1, and the high similarity is benefit to decreasing the non-radiative energy dissipation during geometry reorganization under S1 state, which is helpful in increasing the fluorescence intensity. In addition, the appreciable overlap between electron donor NTO and electron acceptor NTO in S1 state induce to the large oscillator strength of deexcitation, which also attribute to the strong fluorescence.