Reversible 1:1 Inclusion Complexes of C$_{60}$ Derivatives in $\alpha$- and $\beta$-Cyclodextrins Implications for Molecular Recognition-Based Sensing and Supramolecular Assembly

TL;DR

This study presents a novel, efficient method for synthesizing reversible 1:1 complexes of C60 derivatives with alpha- and beta-cyclodextrins, with potential applications in molecular sensing and supramolecular assembly.

Contribution

It introduces a new solvent-induced reversible recognition pathway for C60-CD complexes, including the first reported alpha-CD complex, expanding the scope of supramolecular chemistry.

Findings

Successfully synthesized and confirmed three C60-CD complexes.

Achieved high-efficiency solid-state complex formation.

Demonstrated potential for molecular recognition-based sensing.

Abstract

We developed a novel pathway to highly efficiently synthesize the [60]Fullerene (C$_{60}$)-Cyclodextrin (CD) complex, which is termed as solvent-induced reversible recognition. Three kinds of typical complexes, namely, C$_{60}$-2GUA$^+$-$\alpha$-CD, C$_{60}$-2GUA$^+$-$\beta$-CD and C$_{60}$-4OH-$\beta$-CD, were synthesized. The chemical structure of all complexes was fully confirmed by Fourier transform infrared spectroscopy, Nuclear magnetic resonance (NMR), UV-Vis spectroscopy and the solubility test. Furthermore, crystalline status and thermal degradation were recorded by X-ray diffraction and Thermogravimetric analysis, respectively. Both the NMR and ESI-MS results clearly confirmed the 1:1 complex of C$_{60}$ derivatives with CD. The pathway overcame the preparation limitation of traditional complex, and was extended to the prepare $\alpha$-CD containing complex. To the best of our knowledge, it is the first time to report $\alpha$-CD related complex. The geometric relation between C$_{60}$ and CD for all the three kinds of complexes were analyzed. We can achieve high efficiency to obtain solid-state complex products, which lays the foundation for the widely practical application of complex and provides enough experimental basis for the advanced application of C$_{60}$ and CD in supramolecular assembly. Notably, the solvent-induced reversibility and ionic instability of the complex provides a new possibility for the molecular recognition-based sensing.