Photochromic Properties of Rare Earth Macrocylic Complexes of Curcumin

Rare earth macrocylic complexes of double-double of curcumin reduction diethylenetriamine (L) have been synthesized by the template reaction and have been characterized by H-1 NMR, IR, thermal analysis, molar conductivity and element analysis. Their compositions were confirmed as following: [LnL(NO3)(3)]center dot 4H(2)O (Ln=La, Ce, Pr, Nd, Sm, Eu, Dy). The fluorescent properties of these complexes were studied at room temperature and shown the characteristic emissions of curcumin. Through research of photochromic of these complexes, it was found the complexes show good photochromic. Moreover, the photochromic property of the complexes was studied by the methods of steady state and time dependent fluorescence spectra. The structure of ligand in complex changed from -NH- to =N- under light. The influence of solvent on the photochromic property of the complexes was also investigated.