Cyclic benzobisimidazolium derivative for the selective fluorescent recognition of HSO₄-via a combination of C–H hydrogen bonds and charge interactions

In this study, a novel fluorescent cyclic benzobisimidazolium derivative was designed and prepared for the selective recognition of HSO₄-. Pre-organization, neutral C–H hydrogen bonds and charge interactions play key roles in recognizing HSO₄-in aqueous solution. Spectroscopic studies, including UV-vis and fluorescence, showed that this cyclic receptor exhibited high selectivity in response to HSO₄-. X-Ray crystal data, NMR data and theoretical calculations are presented to explain its unique binding mode.