A cucurbit[8]uril-stabilized 3D charge transfer supramolecular polymer with a remarkable confinement effect for enhanced photocatalytic proton reduction and thioether oxidation

Abstract

A highly water-soluble tetrahedral compound T1 that contains one tetraphenylmethane core and four 2-oxynaphthelene-CH₂-4,4′-bipyridinium (NP-CH₂-DIPY) side arms has been prepared. Control experiments reveal that NP-CH₂-BIPY undergoes antiparallel dimerization which is stabilized by two charge transfer interactions with NP as an electron-rich donor and BIPY as an electron-deficient acceptor. This binding motif drives T1 to aggregate into a nanoscale supramolecular polymer SP in water. Adding 2 equivalents of cucurbit[8]uril to the solution of SP leads to the formation of a more stable three dimensional supramolecular polymer CBSP through a 2 + 2 binding motif in which two CB[8] rings encapsulate one charge transfer complex formed by the antiparallel NP-CH₂-DIPY dimer. As a water soluble porous supramolecular polymer, CBSP exhibits a remarkable confinement effect for visible light-induced proton reduction to produce hydrogen and L-methionine thioether oxidation to the corresponding sulfoxide derivative in water.