The impact of trans/cis photoisomerization on photoinduced electron transport between 4,4′-stilbenedicarboxylic acid and columnar perylenediimide aggregates in water

Abstract

Photoinduced electron transfer (PET) between self-assembled trans- or cis-isomer of 4,4′-stilbenedicarboxylic acid (SDBA) and [N,N′-di(2-(trimethylammoniumiodide)ethylene)]perylenediimide (PDI-I) in water has been investigated. Both trans-SDBA and cis-SDBA molecules can form stable complexes with columnar PDI-I aggregates in water with a 1:1 stoichiometry via ionic interactions, but the complex of cis-isomer is more stable as revealed by the UV-vis absorption and fluorescence spectroscopy. The electrochemical experiments suggest that cis-SDBA is a better electron donor than its trans-isomer. However, fluorescence quenching experiments suggest that the electron transfer from trans-SDBA is more efficient than that from cis-SDBA, which is obviously contradictory to the results of binding constant and the electrochemical experiments. The contradictory results can be attributed to that the columnar aggregates (PDI-I)n are utterly destroyed in cis-SDBA-(PDI-I)n system caused by stronger ionic interaction between cis-SDBA and (PDI-I)n. Also, the bending conformation of cis-SDBA probably results in a larger distance between cis-SDBA and the surface of (PDI-I)n. The results of this research suggest that the electron transfer can be tuned by the aggregation and/or configuration of the donors and acceptors.