Dual and sequential locked/unlocked photo-switching effects on FRET processes by tightened/loosened nano-loops of diarylethene-based [1]rotaxanes.

Abstract

The self-trapping nano-loop structures of [1]rotaxanes exhibited multiple Förster resonance energy transfer (FRET) patterns via dual and sequential locking/unlocking of pH-gated and UV exposure processes. As a tightened and constrained nano-loop in the acidic condition, dithienylethene (DTE) unit was locked in the highly bending open form to forbid ring closure upon UV irradiation.