BCSJ : Vol. 78 (2005) , No. 7 pp.1362-1367

Singlet Energy Transfer and Photoinduced Electron Transfer in Star-Shaped Naphthalimide Derivatives Based on Triphenylamine

Weihong Zhu¹⁾, Yisheng Xu¹⁾, Yan Zhang¹⁾, Jianping Shen¹⁾ and He Tian¹⁾

1) Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology

(Received January 13, 2005)

A series of star-shaped naphthalimide derivatives (TPA-NP) were synthesized with a triphenylamine (TPA) core and chromophores at the rim. Their steady-state absorption, fluorescence, and transient fluorescence spectra were investigated, indicative of severely fluorescent quenching with regard to the corresponding 1,8-naphthalimide (NP) parent chromophores. Excitation into either the triphenylamine or naphthalimide absorption bands results in the occurrence of singlet energy transfer and photoinduced electron transfer (PIET) effectively. Single photon-counting experiments show a fast charge separation and a thermally activated back reaction. As a consequence, the fluorescent lifetime of the naphthalimide moiety in the system of TPA-NP is reduced by more than an order of magnitude, which mainly arises from the intramolecular PIET process of TPA and naphthalimide. The kinetics and PIET mechanism involving TPA-NP were elucidated.