Modulation of Excited‐State Proton Transfer Dynamics Inside the Nanocavity of Microheterogeneous Systems: Microenvironment‐Sensitive F?rster Energy Transfer to Riboflavin

摘要： Excited-state proton transfer (ESPT) in a tetraarylpyrene derivative, 1,3,6,8-tetrakis(4-hydroxy-2,6-dimethylphenyl)pyrene (TDMPP), was investigated thoroughly in the presence of various surfactant assemblies such as micelles, vesicles, etc. The surfactants can significantly retard the extent of excited-state proton transfer process, resulting in a distinguishable optical signal compared to that in the bulk medium. Physical characteristics of the surfactant assemblies such as order, interfacial hydration and surface charge influence the proton transfer process, and allow multiparametric sensing. A higher degree of interfacial hydration facilitates the proton transfer process, while the positively charged head groups of the surfactants specifically stabilize the anionic form of the probe (TDMPP-O*). Further, Forster energy transfer from the probe to riboflavin was studied in phospholipid membrane, wherein the relative ratio of neutral vs anionic forms (TDMPP-OH/TDMPP-O*) was found to influence the extent of energy transfer. Overall, we demonstrate how an ultrafast photophysical process, that is, the excited-state proton transfer, can be influenced by microenvironment.