A molecule with aggregation-induced emission for the pH sensing and anti-counterfeiting applications

In this paper, a meaningful pH sensor (E)-4-(4-(1,2,2-triphenylvinyl) styryl)quinoline (TPQ) with aggregation- induced emission (AIE) effect was synthesized based on the conjugated 4-(1,2,2-triphenylvinyl)benzaldehyde and 4-methylquinoline connected by a C--C - - C bond. The conjugated quinoline moiety acts as a proton acceptor, and the small variations of pH value in the linear range of 4.01-7.03 and 7.96-9.45 can cause obvious fluorescence fluctuations. The TPQ has good selectivity and reversibility in pH detection, and importantly, it can detect pH fluctuations in real-time in practical applications by fluorescent means. Moreover, TPQ can also be used as a potential viscosity fluorescence sensor for organic solvents. In addition, by combining various color changes of TPQ caused by acid, alkali, water and ammonia stimulation under sunlight and 365 nm ultraviolet light irradiation, it provides a novel concealed optical anti-counterfeiting technique with high security. Therefore, TPQ is a multifunctional molecule with great potential for applications in pH, viscosity sensing and anti- counterfeiting.