Threading a Linear Molecule Through a Macrocycle Thanks to Boron: Optical Properties of the Threaded Species and Synthesis of a Rotaxane

Angew Chem Int Ed Engl. 2024 Mar 18;63(12):e202318297. doi: 10.1002/anie.202318297. Epub 2024 Feb 12.

Abstract

Two BODIPYs and two boron β-diketonates were threaded through a macrocycle bearing a 2,2'-biphenol unit, showing thus the ability of boron to act as a gathering atom. The new threaded species were characterized by 1D and 2D NMR spectroscopy as well as by X-ray crystallography for one of them and their properties rationalized with quantum chemistry to unravel the vibronic contributions. The BODIPYs exhibited interesting fluorescence features with quantum yields up to 91 % and enhanced photostability compared to their non-threaded homologues. A rotaxane was synthesized using this threading strategy after stoppering and removing the boron with potassium hydroxide.

Keywords: BODIPY; Boron; DFT; Fluorescence; Rotaxane.