Fluorescence lifetime mapping of hydrophobic microenvironments via self-assembly of a 7-azaindole probe.

A β-dicyano-substituted derivative of 1,4-diethenylbenzene and 7-azaindole (compound 1) has been synthetized and studied as a fluorescence lifetime probe that is sensitive to hydrophobic environments. This probe displays Aggregation-Induced Emission (AIE) in water/tetrahydrofuran mixtures, resulting in different optical properties in steady-state and time-resolved measurements in hydrophobic and hydrophilic environments. By modulating the equilibrium between free and aggregated species, it is possible to detect microenvironmental changes using fluorescence lifetime measurements. Owing to these properties, compound 1 is well suited for fluorescence lifetime imaging microscopy (FLIM), as demonstrated by FLIM experiments that enabled the generation of hydrophobicity maps in human breast cancer cells (MCF-7).