Switchable protection and exposure of a sensitive squaraine dye within a redox active rotaxane

• DOI: 10.1038/s42004-024-01312-1
• Publication Date: 2024-10-04T16:02:03Z
• Authors: Janos Wasternack; Hendrik V. Schröder; J. Felix Witte; Mihkel Ilisson; Henrik Hupatz; Julian F. Hille; Marius Gaedke; Arto M. Valkonen; Sebastian Sobottka; Alexander Krappe; Mario Schubert; Beate Paulus; Kari Rissanen; Biprajit Sarkar; Siegfried Eigler; Ute Resch-Genger; Christoph A. Scha...
• Keywords: Rotaxane; Molecular switch

Abstract In nature, molecular environments in proteins can sterically protect and stabilize reactive species such as organic radicals through non-covalent interactions. Here, we report a near-infrared fluorescent rotaxane which the stabilization of chemically labile squaraine fluorophore by coordination tetralactam macrocycle be controlled electrochemically. The switched between two co-conformations wheel either stabilizes or exposes fluorophore. Coordination affects squaraine’s stability across four redox states renders radical anion significantly more stable—by factor 6.7—than without protection mechanically bonded wheel. Furthermore, fluorescence properties tuned reactions stepwise manner. Mechanically interlocked molecules provide an excellent scaffold to selectively expose co-conformational switching process external stimuli.