A mechanically self-locked gemini-[1]rotaxane-assembled microsphere and its properties on l-Arg controlled reversible morphology and fluorescence changes

Abstract

Herein, a novel pillar[5]arene-based gemini-[1]rotaxane molecule DEP5 was successfully designed and synthesized. Interestingly, the gemini-[1]rotaxane DEP5 serving as a chemosensor could selectively recognize L-Arg with high sensitivity and its lowest detection limit (LOD) was 1.43 × 10⁻⁷ M. Simultaneously, the gemini-[1]rotaxane DEP5 could assemble into the microsphere structure and its microsphere morphology could transform into cross-linked supramolecular networks through host–guest interactions with L-Arg. Furthermore, its microsphere morphology could be recovered again by the addition of competitive reagent guest trifluoroacetic acid (TFA). Therefore, this work provides a new and simple approach to construct gemini-[1]rotaxane-based smart materials which could assemble into the microsphere in solution and achieve reversible regulation of morphology between the microsphere and cross-linked supramolecular networks by external chemical stimuli (L-Arg/TFA). This kind of material not only has a perspective in L-Arg sensors but also has potential for application in other fields such as drug control release.