Schiff base-type Cu(I) complexes containing naphthylpyridyl-methanimine ligands featuring higher light-absorption capability: Synthesis, structures, and photophysical properties

Herein, the three novel copper (I) complexes bearing Schiff base ligands of the types [Cu(Methoxyphenyl-NaphthylPyridyl-Meth-Aniline)(POP)]PF6 (P1), [Cu(NaphthylPy-Methylene-Adam-Amine)(POP)]PF6 (P2), and [Cu(Dipp-NaphthylPyridyl-Meth-Aniline)(POP)]PF6 (P3) (Methoxyphenyl-NaphthylPyridyl-Meth-Aniline = 4-methoxyphenyl-N-((5-(naphthalen-1-yl)pyridin-2-yl)methylene)aniline, NaphylPy-Methylene-Adam-Amine = N-((5-(naphthalen-1-yl)pyridin-2-yl)methylene)adamantan-1-amine, Dipp-NaphylPyridyl-Meth-Aniline = 2,6-dii-sopropylphenyl-N-((5-(naphthalen-1-yl)pyridin-2-yl)methylene)aniline, POP = bis[2-diphenylphosphino]-phenyl)ether) have been prepared and investigated. The different groups such as methoxyphenyl, adamantyl and diisopropylphenyl were functionalized onto the azomethine unit of the Schiff base ligands to tune the photo -physical behaviors of the resulting Schiff base Cu(I) complexes. All the complexes exhibit the lowest energy metal-to-ligand charge transfer (MLCT) characters in the visible region with higher molar extinction coefficients on the order of 104 M-1 cm(-1), making them much attractive as photosensitizers in optoelectronic and light -harvesting applications. Blue-green emissions in the region of 479-513 nm with photoluminescence quantum yields (PLQY) of 0.8-1.2 % can be observed in CH2Cl2 solution. Additionally, the photophysical properties are also investigated theoretically using density functional theory (DFT) and time dependent DFT.