Designing the selectivity of the fluorescent detection of amino acids. A chemosensing ensemble for histidine

The imidazole group of histidine deprotonates and bridges the two CuII centers of a dimetallic polyamine macrocyclic complex, displacing the previously bound and quenched fluorescent indicator I. Thus, histidine recognition is signaled by the revival of the fluorescence of I. Selectivity with respect to other natural amino acids is achieved by choosing an indicator of tuned affinity toward the dicopper(II) receptor.