A series of new emissive mononuclear copper(I) bipyridyl complexes bearing the methoxycarbonyl groups

•Three new mono-Cu(I) bipyridyl complexes 1–3 with the methoxycarbonyl groups•Structures and properties of 1–3 are affected by phosphine and the substituents.•Weak low-energy absorption from charge-transfer states with appreciable MLCT nature•The Cu⋯Ocarbonyl distance and the dihedral angle affect the solid-state emission.

A new series of mononuclear copper(I) complexes 1–3 possessing functionalized 6-methoxycarbonyl-2,2′-bipyridine and phosphine mixed ligands have been synthesized and characterized. Each Cu(I) atom gives an N2P2 distorted tetrahedral configuration, in which the dihedral angles between two pyridyl rings follow a ranking of 1 (4.640°) < 2 (av. 9.065°) < 3 (15.648°), while a reverse order lies in the dihedral angles between the methoxycarbonyl and its conjoined pyridyl ring (1 (15.224°) > 2 (av. 8.983°) > 3 (2.786°)). Complexes 1–3 show a weak low-energy absorption band at 330–500 nm in CH2Cl2 solution, ascribed to charge-transfer transitions with appreciable 1MLCT character, as supported by TD-DFT calculations. The solid-state luminescence is observed in 1–3 at room temperature, which is affected by the phosphine, the substituents on the 2,2′-bipyridyl, and the above-mentioned dihedral angles.

Graphical abstractA new series of mononuclear Cu(I) complexes 1–3 with functionalized 6-methoxycarbonyl-2,2′-bipyridine and phosphine mixed ligands have been synthesized and characterized. The solid-state luminescence properties of 1–3 are influenced by the phosphine ancillary ligand and the substituents of the 2,2′-bipyridyl ring.Figure optionsDownload full-size imageDownload as PowerPoint slide