Visible-light-responsive lanthanide coordination polymers for highly efficient photocatalytic aerobic oxidation of amines and thiols

Abstract

Development of visible-light-induced photocatalytic reactions using molecular oxygen as the terminal oxidant is intriguing in view of the current environmental and energy issues. We report herein the synthesis and characterization of a series of novel photocatalysts of lanthanide coordination polymers (Ln-CPs) with desirable characters of wide-range visible-light adsorption and excellent chemical stability. They show excellent selectivity and yield for the aerobic oxidation of amines and thiols to produce imines and disulphide, respectively. Mechanism studies including electron paramagnetic resonance and radical quenching indicate these Ln-CPs are highly efficient to activate molecular oxygen into highly reactive oxygen species of superoxide radical and singlet oxygen via photoinduced electron and energy transfer, respectively. It is notable that the photocatalytic oxidation of thiols into disulphide have never been reported using a CP photocatalyst prior to this study. Meanwhile, the synthesized CPs exhibits superior photocatalytic performance to other reported ones for amine oxidation due to the synergy of singlet oxygen and superoxide radical species. The work provides an in-depth understanding of the photoinduced oxygen activation based on a CP photocatalyst to accomplish a visible-light-induced reaction, illustrating the great potential of photoactive CPs for green synthesis.