Photooxidase Mimicking with Adaptive Coordination Molecular Capsules

One important feature of enzyme catalysis is the induced-fit conformational change after binding substrates. Herein, we report a biomimetic water-soluble molecular capsule featuring adaptive structural change toward substrate binding, which offers an ideal platform for efficient photocatalysis. The molecular capsule was coordination-assembled from three anthracene-bridged bis- TPT [TPT = 2,4,6-tris(4-pyridyl)-1,3,5-triazine] ligands and six (bpy)Pd(NO3)(2) (bpy = 2,2'-bipyridine). Once substrates bind to its hydrophobic cavity, this capsule would undergo quantitative capsule-to-bowl transformation. Visible-light absorption brought about by both the anthracene units and the charge-transfer absorption on the late-formed quintuple pi-pi stacked host-guest complex efficiently facilitates aerobic photooxidation for the sulfide guests by visible-light irradiation under mild conditions. Desired turnover numbers and product selectivity (sulfoxide over sulfone) have been achieved by the transformable nature of the catalyst and the hydrophilicity of the sulfoxide product. Such a photocatalytic process enabled by an adaptive coordination capsule and substrates as the allosteric effector paves the way for constructing artificial systems to mimic enzyme catalysis.

Automated summary

The adaptive molecular capsule with structural changes upon substrate binding allows for efficient photocatalysis, paving the way for artificial systems mimicking enzyme catalysis. The capsule undergoes quantitative transformation when substrates bind to its hydrophobic cavity, facilitating aerobic photooxidation for the sulfide guests under mild conditions. Through the transformable nature of the catalyst and the hydrophilicity of the sulfoxide product, desired turnover numbers and product selectivity have been achieved.