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

Abstract

A new fluorescent ligand (φ_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 Å. X-ray structure reveals weak Cu···O interactions between copper and one of the imide oxygen atoms of the ligand framework. Additional weak Cu···O interactions between copper and oxygen atoms of the ClO₄⁻ counteranion are detected that lead to a zigzag polymeric chain with alternate ClO₄⁻ 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.