Efficient synthesis, photochromism, and holographic optical recording of a photochromic diarylethene bearing a pyrrole unit

Abstract

A unsymmetrical photochromic diarylethene, 1-[2-methyl-5-(4-chlorophenyl)-3-thienyl]-2 -(2-cyano-1, 5-dimethyl-4-pyrryl)hexafluorocyclopentene (1a), was synthesized, and its photochromic and fluorescent properties were also investigated. The results showed that this compound exhibited reversible photochromism, changing from colorless to blue after irradiation with UV light both in solution and in PMMA amorphous film. The open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 412 nm in hexane solution (5×10 -5 mol/L) and 417 nm in PMMA amorphous film when excited at 320 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light and its closed-ring isomer showed almost no fluorescence. The fluorescence spectra of diarylethene 1a depended on the concentration and the polarity of the solvent. Using diarylethene 1 as recording medium, polarization holographic optical recording was carried out successfully.