Light-Regulating Olefin Polymerization Featuring Dithienylethene Switches

Dithienylethene (DTE) derivatives represent a promising organic photochromic unit, which can undergo a reversible transformation from a ring-open isomer (o-isomer) to a ring-closed isomer (c-isomer) under ultraviolet (UV) light. Herein, we synthesized binuclear pyrimidine and α-diimine nickel catalysts connected by a cyclopentacene- or perfluorocyclopentene-type DTE unit, enabling light-mediated modulation of reactivity and selectivity in ethylene polymerization. Under UV irradiation, these photoswitchable catalysts displayed significant enhancement in polymerization activity and produced polyethylene with higher branching density and lower molecular weight compared to that under dark conditions. Notably, in ethylene-polar monomer copolymerization, light can also increase the catalytic activity and comonomer incorporation. The robust photochromic DTE moiety significantly broadens the applicability scope and enhances the operability of the photochemistry control strategy.