Fluorescent Imidazolium-Based Cyclophane for Detection of Guanosine-5′-triphosphate and I in Aqueous Solution of Physiological pH

A new water-soluble and fluorescent imidazolium-anthracene cyclophane (1) effectively recognizes the biologically important GTP and I over other anions in a 100% aqueous solution of physiological pH 7.4. Fluorescence and 1H NMR spectra and ab initio calculations demonstrate that emission arises from the formation of an excimer state and quenching occurs upon GTP/I binding through (C–H)+···A hydrogen bond interactions.