In situ reduction of copper(II) forming an unusually air stable linear complex of copper(I) with a fluorescent tag

A new fluorescent ligand (phi(f) = 0.8 in dioxane), 2-(4'-aminophthalimidomethyl)pyridine (L), has been synthesized. A one-pot synthesis of its copper(I) complex upon reduction of copper(II) is achieved at room temperature. This complex, which has been characterized by X-ray crystallography, shows a linear N-Cu-N geometry with Cu-N bond lengths of 1.89 Angstrom. X-ray structure reveals weak (CuO)-O-... interactions between copper and one of the imide oxygen atoms of the ligand framework. Additional weak (CuO)-O-... interactions between copper and oxygen atoms of the CIO4- counteranion are detected that lead to a zigzag polymeric chain with alternate CIO4- and copper ions. A 2-D intermolecular hydrogen bonding network is also observed. This complex is found to be highly inert toward oxidation both in the solid state and in solution.