Engineering Rotaxane-Based Nanoarchitectures via Topochemical Photo-Cross-Linking

Abstract

Polymerization of monomers included by macrocyclic hosts has been found as an efficient way to synthesize sophisticated rotaxane-based nanostructures, whereas such a process triggered by photon has received little coverage so far. Herein, a new diphenyldiacetylene (DPDA) derivative (compound 1) comprising viologen as a binding site toward cucurbit[7]uril (CB[7]) macroring, and isophthalate as a bulky stopper, was rationally designed and prepared. After verifying the photo-cross-linking efficiency of compound 1 upon its regular self-assembly, we also achieved a straightforward construction of rotaxane-based nanoarchitecture 2 ⊂ CB[7] through an in situ photoirradiation on the corresponding pseudo[2]rotaxane 1 ⊂ CB[7]. Although the threading of CB[7] changed the self-assembly behavior of the DPDA derivative, the topochemical reaction could be definitely observed to afford the corresponding photo-cross-linked species. Such a process could be facilely indicated by distinctive photoluminescence enhancement on the basis of π-conjugated skeleton change of DPDA toward potential usage of rotaxane-based systems as smart optoelectronic materials. We anticipate this unique strategy will allow new visions for the synthesis and application of novel luminescent host–guest nanoarchitectures.