Remarkably Selective Binding, Behavior Modification, and Switchable Release of (Bipyridine)3Ru(II) vis-à-vis (Phenanthroline)3Ru(II) by Trimeric Cyclophanes in Water

Hong-Yu Lin, Chao-Yi Yao, Jialu Li, H. Q. Nimal Gunaratne, Warispreet Singh, Meilan Huang, Eric V. Anslyn, A. Prasanna De Silva*

*Corresponding author for this work

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A recurring dream of molecular recognition is to create receptors that distinguish between closely related targets with sufficient accuracy, especially in water. The more useful the targets, the more valuable the dream becomes. We now present multianionic trimeric cyclophane receptors with a remarkable ability to bind the iconic (bipyridine)3Ru(II) (with its huge range of applications) while rejecting the nearly equally iconic (phenanthroline)3Ru(II). These receptors not only selectively capture (bipyridine)3Ru(II) but also can be redox-switched to release the guest. 1D- and 2D(ROESY)-NMR spectroscopy, luminescence spectroscopy, and molecular modeling enabled this discovery. This outcome allows the control of these applications, e.g., as a photocatalyst or as a luminescent sensor, by selectively hiding or exposing (bipyridine)3Ru(II). Overall, a 3D nanometric object is selected, picked-up, and dropped-off by a discrete molecular host. The multianionic receptors protect excited states of these metal complexes from phenolate quenchers so that the initial step in photocatalytic phenolate oxidation is retarded by nearly 2 orders of magnitude. This work opens the way for (bipyridine)3Ru(II) to be manipulated in the presence of other functional nano-objects so that many of its applications can be commanded and controlled. We have a cyclophane-based toolkit that can emulate some aspects of proteins that selectively participate in cell signaling and metabolic pathways by changing shape upon environmental commands being received at a location remote from the active site.
Original languageEnglish
Pages (from-to)2257-2268
Number of pages12
JournalJACS Au
Issue number8
Early online date28 Jul 2023
Publication statusPublished - 28 Aug 2023

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