A Cucurbit[8]uril-mediated Host-guest Complex for Red Light Photocatalysis

Abstract

A red light supramolecular photocatalytic system is developed by fabricating a cucurbit[8]uril-mediated 3:2 host-guest complex. Two-step host-guest complexation can be occurred between 4, 4'-(thiazolo[5, 4-d]thiazole-2, 5-diyl) bis (6-(pyrrolidin-1-yl)-[1, 3-bipyridin]-1-ium) chloride (TPP), a long-axis molecule, and cucurbit[8]uril (CB[8]), leading to the formation of two host-guest complexes, CB[8]@2TPP and 3CB[8]@2TPP, sequentially. The formation of CB[8]@2TPP and then 3CB[8]@2TPP lead to the continuously enhanced intermolecular interaction between TPPs, and 3CB[8]@2TPP eventually exhibits considerable red light absorption ability and long-lived triplet state. In addition, the electron transfer as well as energy transfer between 3CB[8]@2TPP and oxygen proceed smoothly. As a result, 3CB[8]@2TPP can serve as an efficient red light photocatalyst for the oxidation of boronic acids.