Self-assembling, chromogenic receptors for the recognition of medically important substrates and their method of use

A chromogenic receptor comprises a self-assembled chromogenic compound having at least one intrinsic binding site. The chromogenic compound is characterized by the property of producing a reversible color change responsive to binding a target substrate to the receptor. The chromogenic compound has a transition metal ion and at least one ligand bound to the transition metal ion. The ligand is selected from the group consisting of substituted phenanthroline, substituted 2,2'-bipyridine and substituted 2,2':6',2''-terpyridine. The transition metal is selected from the group consisting of Cu(I), Cu(II), Ag(I), Ni(II), Fe(II), Fe(III), Ru(II), Co(III), and Os(II). Self-assembly can be effected in the presence of Cu(I) to form receptors for dicarboxylic acids, carbohydrate, amino acids, steroids and pyrophosphates. The receptors are characterized by the formation of a 2:1 complex of the target substrate with the receptor producing a visible color change from orange to red and a measurable change in its luminescence. Methods of using these receptors are also disclosed.