Activatable molecular rotor based on bithiophene quinolinlium toward viscosity detection in liquid

Abstract

Noninvasive and effective viscosity inspection method during the liquid deterioration process is urgent to be developed, since viscosity is one of the most important physical parameter toward liquid. The method with rapid detection, high sensitivity, cheap equipment, and fast results output is obliged to be exploited. In this study, one kind of viscosity-sensitive molecular rotor (BTPEQ) with large Stokes shift (187 nm), and long emission wavelength (648 nm) has been developed. The rotor comprised bithiophene donor and quinolinium acceptor, and displayed typical twisted intramolecular-charge transfer (TICT) feature, with good photostability, selectivity, universality in various commercial liquids. With the aid of BTPEQ, the thickening effects of liquid thickeners can be captured. More importantly, BTPEQ was explored to visualize the viscosity variations in the liquids at different metamorphic stages, and found that the microenvironment viscosity level is highly dependent on the liquid food metamorphic period. It is noting that this approach can facilitate the continued perfection of fluorescent analytical methods toward food quality and safety inspection.