Ratiometric fluorescence emitters in tightened / loosened lassos (nano-loops) of [1]rotaxanes and their applications on temperature and viscosity sensors

Abstract

A ratiometric fluorescence emitter based on nano-loops of tightened / loosened lassos of [1]rotaxane is provided. The emitter includes a [1]rotaxane with a bent lasso structure, which has the following moieties. A macrocyclic moiety has a cyclic polyether structure. A ratiometric fluorophore moiety is covalently bonded to the macrocyclic moiety. This fluorophore exhibits a bent conformation that emits cyan light and a twisted conformation that emits orange light. A first station moiety is bonded to the ratiometric fluorophore moiety. The first station moiety enters the macrocyclic moiety in an alkaline environment and forms multiple hydrogen bonds to stabilize the bent conformation. A linear moiety is connected to the first station moiety and is threaded through the macrocyclic moiety. A second station moiety is bonded to the linear moiety. The second station moiety enters the macrocyclic moiety in an acidic environment and forms multiple hydrogen bonds, inducing a vibration equilibrium between the bent and twisted conformation of the fluorophore. A stopper moiety is positioned on the opposite side of the macrocyclic moiety and is bonded to the second station moiety.

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