Sumanene-based triazole-linked receptors

Abstract

Designing molecular receptors featuring the bowl-shaped sumanene motif for detecting metal cations constitutes an emerging field of applied supramolecular chemistry of this buckybowl. In this work, we successfully synthesized a new class of sumanene-based receptors, whose key structural feature was the presence of two or three sumanene units linked via 1,2,3-triazole skeletons generated in a 1,3-dipolar cycloaddition reaction (click chemistry approach). It was found that the designed compounds detect metal cations in solution (spectrofluorometric studies), as well as in heterogeneous systems (polymeric membranes of potentiometric sensors). In terms of optical studies in solution, the title molecules exhibited fluorescence quenching behaviours upon addition of metal cations, with Stern–Volmer constant values at the level of 10⁶ M⁻¹. The spectrofluorometric and potentiometric results were in good agreement, revealing the preferential binding of lithium (Li⁺), caesium (Cs⁺), or copper(II) (Cu²⁺) cations, depending on the receptor structure. Density functional theory (DFT) computational studies were also performed on the structure and receptor properties of the title molecules. The results indicate attractive possibilities for the design of novel organic materials based on the sumanene scaffold and the ability to tune the properties of sumanene-based receptors for recognition of different metal cations.