Lewis Acid Modulation in a Amido-functional Diarylethene and Its Hypsochromism Effect

A photochromic diarylethene, 1,2-bis(2-methyl-5-(4-N,N-dimethylaminophenyl)thien-3-yl)perfluorocyclopentene in proton-donating media was studied. The ammonium salt came into being in the presence of acetic acid following localization of lone pair electrons of the amino group. The maximum absorption of the salt had a 36 nm hypsochromic shift, and its molar extinction coefficient increased to 3.494×104 L·mol−1·cm−1. The conjugational and delocalizational energy levels were calculated by Gaussian 98, and its hypsochromic shift mechanism was also discussed.