Computer-guided design of a Cu(II) receptor and sensor

The computer program CAVEAT was used to design a linker structure to connect four imidazole 4-carboxamide groups in a distorted square planar arrangement optimal for binding Cu(ii) ions. The resulting macrocyclic structure was prepared by the synthesis of a protected monomer followed by amide coupling reactions to form the cyclic tetramer. Binding to Cu(ii) ion was evaluated using the inherent fluorescence of the receptor and its quenching upon binding to Cu(ii) ion. Much higher concentrations of Zn(ii), Co(ii), and Ni(ii) ions had little or no effect on the fluorescence and did not significantly compete with the fluorescence response to Cu(II) ions.