Cucurbit[7]uril-Mediated 2D Single-Layer Hybrid Frameworks Assembled by Tetraphenylethene and Polyoxometalate toward Modulation of α-Chymotrypsin Activity.

Construction of large scale single-layer 2D frameworks in water is significant as their superiorities in various fields. Utilizing macrocycle mediated supramolecular self-assembly represents a promising approach, however challenges still remain in practical preparation. Here we exploited a two-step supramolecular strategy to build 2D organic-inorganic hybrid frameworks at micrometre-scale in water. Taking advantage of the high binding affinity to cucurbit[7]uril (CB[7]), mono-quaternary ammonium tetraphenylethene derivatives (MQATPE) were firstly included with CB[7] to form 1:1 complex (MQATPE@CB[7]). Then just mixing the complex with anionic polyoxometalate Na9[EuW10O36]•32H2O (denoted as Eu-POM) at a 3:1 molar ratio leads to the formation of single-layer 2D films with tens of micrometers via electrostatic and π-π stacking interactions. The most unique feature of this strategy is that the steric effect imposed by CB[7] would not only lead the modules to adopt a periodic hexagonal assembly, but also forbid stacking between layers, through comparing with the merely multilayered 2D nanosheets self-assembled by MQATPE/ Eu-POM. Interestingly, the charge interactions between MQATPE and Eu-POM would lead to the aggregation-induced emission (AIE) fluorescence of MQATPE, and white-light emitting could be obtained through simple regulation the contents of Eu-POM and MQATPE. Furthermore, due to the high surface areas and more accessible active sites, the single- layer films can act as an effective enzyme inhibitor to modulate the activity of α-chymotrypsin (ChT). These findings suggest a simple but universal approach for single-layer hybrid materials which may hold promise for practical applications in photophysical and biomedical fields.