Sumanene–carbazole conjugate with push–pull structure and its chemoreceptor application

Abstract

The first-of-its-kind tetra-substituted sumanene derivative, featuring the push–pull chromophore architecture, has been successfully designed. The inclusion of both strong electron-withdrawing (CF₃) and electron-donating (carbazole) moieties in this buckybowl compound has enhanced the charge transfer characteristics of the molecule. This enhancement was supported by ultraviolet-visible (UV-Vis) and emission spectra analyses along with density functional theory (DFT) calculations. The application of the title sumanene–carbazole push–pull chromophore as a selective recognition material for cesium cations (Cs⁺) was also presented. The title compound exhibited effective and selective Cs⁺-trapping ability, characterized by a high apparent binding constant value (at the level of 10⁵) and a low limit of detection (0.09–0.13 μM). Owing to the tuned optical properties of the title push–pull chromophore, this study marks the first time in sumanene-tethered chemoreceptor chemistry where efficient tracking of Cs⁺ binding was possible with both absorption and fluorescence spectroscopies. This work introduces a new approach toward tuning the structure of bowl-shaped optical chemoreceptors.