Light-controlled supramolecular self-assembly is a hot topic in the field of supramolecular chemistry and materials chemistry. Recently, Prof. Da-Hui Qu Group achieved remarkable advance in light-controlled assembly of TiO2 nanoparticles (NPs). A paper entitled “Dual-Mode Controlled Self-Assembly of TiO2 Nanoparticles Through a Cucurbit[8]uril-Enhanced Radical Cation Dimerization Interaction” (http://onlinelibrary.wiley.com/doi/10.1002/anie.201509071/abstract) was published in Angew. Chem. Int. Ed. (2015, DOI:10.1002/anie.201509071).
    Construction of stimuli-responsive smart materials by supramolecular interactions, especially host-guest interactions, has been focused importantly due to the significance in supramolecular chemistry and materials chemistry. Based on the redox-responsive host-guest system formed by methyl viologen (MV2+) and cucurbit[8]uril (CB[8]), in this work, MV2+ dication moieties were immobilized onto the surface of TiO2 NPs covalently. Significantly, the electrons produced by TiO2 NPs under UV light irradiation can reduce the MV2+ dications into MV+• radical cations, leading to the typical dimerization of MV+• radical cations in the cavity of CB[8]. Integrating supramolecular host-guest systems with TiO2 semiconductor gave the non-light-responsive host-guest system light-responsive capability, leading to the light-controlled self-assembly of TiO2 NPs. Meanwhile, the process of assembly/disassembly of TiO2 can also switch the performance of TiO2 in photocatalysis reaction, which supports new strategy to construct artificial switchable photocatalysts.

    This work was completed by Qi Zhang, a first-year postgraduates in ECUST. He attended ECUST for his undergraduate studies and obtained his B. S. in fine chemicals in 2015, where he performed this work as his graduation project (distinguished graduation thesis of ECUST in 2015) under the direction of Prof. Da-Hui Qu. He is currently a PhD student in the group of Prof. He TIAN and Prof. Da-Hui Qu and his research interest focuses on light-controlled supramolecular self-assembly and its application.
    The research was supported by NSFC/China (21421004, 21272073, 21190033) and National Basic Research 973 Program.