Tetraphenylethene modified diphenylsulfone derivatives exhibiting a highly twisted conformation, aggregation-induced emission enhancement and mechanochromic luminescence

Two AIEE-active luminophores TPE-DPS-H and TPE-DPS-F, which are constructed by tetraphenylethene unit as electron donor and diphenylsulfone segment as electron acceptor, are prepared using the classical Heck coupling reaction. Through the combination of tetraphenylethene unit and diphenylsulfone segment, both of them possess highly distorted molecular conformation and AIEE (aggregation-induced emission enhancement) characteristics. The emission efficiencies of TPE-DPS-H and TPE-DPS-F in the solid state reach 35.86% and 32.74%, respectively. Interestingly, both TPE-DPS-H and TPE-DPS-F show fluorescent response to mechanical force. Among them, TPE-DPS-H displays reversible and high-contrast mechanochromic luminescence. The emitting color of TPE-DPS-H in the solid state changes from bright cyan to green after grinding with a wavelength shift of 32 nm. XRD and DSC experiments indicate that the phase conversion from well-ordered crystalline state to confused amorphous state is responsible for mechanochromic luminescent performances of TPE-DPS-H and TPE-DPS-F.