The Role of Rigidity in Augmentation of Fluorescence and Room-Temperature Phosphorescence in Multinuclear Zn2+-Schiff Base Complexes.

Abstract

The effect of incorporating an additional metal ion in Zn2+-Schiff base complexes has been investigated using two model compounds: the binuclear Znsalpr and trinuclear Znsalbn, using time-resolved emission spectroscopy. Fluorescence of the trinuclear complex is twice as strong as that of the binuclear one. This is ascribed to a greater extent of rigidity of the trinuclear complex and consequent hindrance offered to nonradiative relaxation involving movement of molecules. Both the complexes exhibit long-lived green afterglow at 77 K, indicating the promotion of intersystem crossing brought about by complexation. Room-temperature phosphorescence is obtained from the complexes in PMMA matrix, thus making them potential candidates for optoelectronic applications.