Fluorescent alteration on a bistable molecular shuttle.

Solvent driven molecular shuttles containing a pyrene-connected macrocycle and an intramolecular charge-transfer (ICT) chromophore stopper are constructed. In one of the molecular shuttles, a long C-10 chain is introduced in the thread to separate the peptide station and the ICT stopper. The macrocycle stays in the peptide station in apolar solvents and moves to the C10-chain station in highly polar solvents. This moving process alters the electronic interaction between the pyrene unit in the macrocycle and the ICT stopper, which induces the change of the pyrene fluorescence emission. The molecular shuttle exhibits stronger emission when the macrocycle is adjacent to the ICT stopper.