posted on 2021-09-23, 11:34authored byDan-Ni Yan, Li-Xuan Cai, Pei-Ming Cheng, Shao-Jun Hu, Li-Peng Zhou, Qing-Fu Sun
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 π–π 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.