Photoresponsive Host-Guest Systems Based on a New Azobenzene-Containing Crytpand

A new azobenzene-bridged cryptand was synthesized; it can be well controlled between cis and trans isomers by irradiation with different wavelengths or by being heated. It was found that this cryptand exhibits an ON-OFF binding ability with 2,7-diazapyrenium (DAP) derivatives. It binds DAP derivatives as the cis isomer only, as demonstrated by various methods. The fluorescence property of DAP derivatives endows these host guest systems with detectable fluorescent output signals, which makes monitoring these photoresponsive systems convenient.