Metal-selective coordination and enhanced fluorescence of a self-assembling ligand scaffold

A fluorescent hydroxyiminonicotinonitile (HINT) coordinating group can be incorporated into self-assembling ligand scaffolds, and shows metal-selective assembly and enhanced fluorescence. The assembly process is dependent on ligand coordination angle, and coordination only occurs for oxophilic first row transition metal ions, with affinity enhanced by the supramolecular assembly process. The ligands are weakly emissive, and show strong enhancement in fluorescence upon Zn²⁺ coordination, whereas Co²⁺ or Fe²⁺ cause complete quenching.