Schiff base-type copper(I) complexes exhibiting high molar extinction coefficients: Synthesis, characterization and DFT studies

The three Schiff base-type Cu(I) complexes [Cu(POP)(N^N)]PF6, N^N = N,N-diphenyl-4-(6-((phenylimino)methyl)pyridin-3-yl)aniline (P1), N-((5-(4-(diphenylamino)phenyl)pyridin-2-yl)methylene)naphthalen-2-amine (P2), N-((5-(4-(diphenylamino)phenyl)pyridin-2-yl)methylene)adamantan-1-amine (P3), were prepared and characterized. The photophysical properties of these Cu(I) complexes is tuned by the addition of different substituents such as phenyl, naphthyl and adamantanyl groups into the backbone of Schiff base ligand. The resulting complexes exhibit high absorption ability in the visible region with molar extinction coefficients of up to 3 7400 M−1 cm−1. The emissions in CH2Cl2 solution are in the range of 551–552 nm with lower quantum yields of 1.1–2.0% and short-lived excited lifetimes of 2.78–3.09 ns for all the complexes at room temperature. The photophysical properties were further explained by DFT and TDDFT methods.