Prolonging triplet-state lifetimes to boost the energy and electron transfer in conjugated organic polymers for photocatalytic amide formation

Abstract

Long-lived triplet excited states have been regarded as active species in the implementation of photochemical strategies owing to their associated high energy and electron transfer abilities, yet it was still challenging to fulfill this in polymeric photocatalysis. Herein, we formulated a built-in donor–acceptor interaction control strategy to prolong the excited-state lifetime in conjugated organic polymers (COPs) by minimizing the exciton binding energy in the first excited state. The resultant COPs decorated with tris([1,2,4]triazolo)[4,3-a:4′,3′-c:4′’,3′’-e][1,3,5]triazine exhibited excellent activities in photocatalytic amide formation (95 % yield), which was much higher than that of triazine rings as an analogous moiety(66 % yield) owing to its prolonged triplet-state lifetimes (τ = 30.5 µs) and the improved photo-induced charge separation efficiency. These results not only demonstrate the feasibility of realizing triplet excited states for heterogeneous photocatalysis through molecular engineering but also offers insights into energy and electron transfer at the molecular level.