An imidazole-appended p-phenylene-Cu(II) ensemble as a chemoprobe for histidine in biological samples

A tetra-imidazole-appended tetrakis(p-phenylene)ethylene 1-Cu(2+) ensemble was found to enhance fluorescence upon addition of histidine, but not with any other amino acids. The 1-Cu(2+) ensemble also selectively detected proteins containing histidine residues in a mixture of water and methanol (90 : 10, v/v%). The 1-Cu(2+) ensemble-coated thin-layered chromatography (TLC) plate could also detect histidine quantitatively. Furthermore, the fluorescence emission recovery upon addition of five concentrations of His was ~80% with good linearity.