Achieving Enhanced Photochromic Property of Diarylethene Through Host-Guest Interaction in Aqueous Solution.

Diarylethene (DTE) has been widely used in fluorescence probes, molecular logic gates, optical data-storage devices owing to the excellent photochromic property, while constructing high-performance photochromic DTE in aqueous media remains a big challenge. Herein we present several host-guest systems formed between cucurbit[ n ]uril (CB[ n ], n = 7, 8, 10) and two water-soluble DTE derivatives 1 and 2 . It was found that host-guest interactions not only affect the photophysical properties of photochromic guests, also make great differences on the photoreaction process. Different host-guest binding behaviors also lead to different effects on the photochromic properties of guests. In the presence of CB[ n ], both 1 and 2 showed enhanced emission and higher fluorescence quenching ratio at photostationary state. Besides, CB[10]• 1 exhibited faster response rate in cyclization reaction and better photofatigue resistance than free 1 in aqueous solution, while the supramolecular assembly of (CB[8]) n •( 2 ) n showed slower response rate in both directions of the reversible photoreaction. Besides, the photofatigue resistance of 2 can be greatly improved through binding with CB[7]. Our results suggest that host-guest interactions could be an efficient way to improve photochromic properties of DTE in aqueous solution.