Emissive mononuclear Cu(I) triphenylphosphine complexes with functionalized 6-tert-butoxycarbonyl-2,2′-bipyridine

Abstract

Two new emissive mononuclear copper(I) triphenylphosphine complexes with functionalized 6-tert-butoxycarbonyl-2,2′-bipyridine chelating ligands were prepared and characterized. Each Cu(I) cation has a markedly distorted P2N2 tetrahedral array with two different Cu—N bond distances, due to the addition of the bulky tert-butoxycarbonyl group at the 6-position of the 2,2′-bipyridyl ring. A weak low-energy broad absorption band appears at 330—500 nm in their CH2Cl2 solutions, which is influenced by the methylation of the 2,2′-bipyridyl ring. At room temperature, the photoluminescence can be clearly observed both in degassed CH2Cl2 solution and in the solid state, because of the introduction of the bulky tert-butoxycarbonyl substituent, and the emission properties are remarkably affected by both the methylation and the alkoxycarbonyl variation of the 2,2′-bipyridyl ring. It is shown that the introduction of the bulky tert-butoxycarbonyl group is favorable for improving the emission properties of the 6-alkoxycarbonyl-2,2′-bipyridine-based cuprous complexes.