Achieving Adjustable Multifunction Based on Host-Guest Interaction-Manipulated Reversible Molecular Conformational Switching

Small molecules that are capable of toggling between multiple and definite conformational states under external stimuli have great potential for use in molecular switches or sensors. However, currently developed regulation approaches for these switchable molecules mostly involve covalent bond-breaking/reforming processes, thereby inevitably producing byproducts or causing fatigue accumulation. Herein, we report a simple but successful model whose molecular conformation can be precisely manipulated between stretched and folded forms by employing host-guest interactions with rigid macrocycles, thus avoiding possible side reactions and fatigue accumulation and possessing excellent reversibility. Moreover, the conformation states of this molecule can be visualized and identified by luminous readout, endowing it with real-time self-reporting features. Furthermore, this controllable and reversible conformational conversion is accompanied by various valuable functions, including controllable multicolor emission; ratiometric fluorescent thermosensing with high temperature resolution, excellent reversibility, lock/unlock switching, and especially linear detection range tunability; and in addition real-time intracellular temperature sensing and imaging, disclosing the intriguing microscopic "conformation-function"relationship based on a single molecule.