Photophysical and electrochemical properties of D–π–A type solvatofluorchromic isophorone dye for pH molecular switch

The photophysical and electrochemical properties of a donor-π-accepter (D–π–A) type isophorone dye, 2-(3-(4-((2-hydroxyethyl)(methyl)amino)styryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile with asymmetrical structure, was investigated. It showed interestingly solvatofluorchromic property in various solvents based on intramolecular charge transfer mechanism. Its LUMO and HOMO values were obtained by electrochemical measurement and theoretical calculation. In addition, it can be also constructed a pH fluorescent molecular switch by modulation of intramolecular charge transfer with protonation/deprotonation.