Orange-red emissive Cu(I) complexes bearing Schiff base ligands: Synthesis, structures, and photophysical properties.

• Schiff base copper (I) complexes bearing the bulky adamantyl moiety were synthesized and characterized. • The electron-donating/withdrawing groups including –OCH 3 and –CF 3 were inserted into the complexes. • Cu(I) omplexes exhibited organe-red emissions at 611–619 nm with shorter excited-state lifetimes of 5.55–7.53 μs. • The origin of the emission is attributed the 3MLCT/3LLCT/3π-π* state supported by the TDDFT calculations. Herein, the three novel copper (I) complexes bearing Schiff base ligands of the types [Cu(Phen-PyMethylene-Adam-Amine)(POP)]PF6 (P1), [Cu(Methoxyl-Phen-PyMethylene-Adam-Amine)(POP)]PF6 (P2), and [Cu(TriflMethyl-Phen-PyMethylene-Adam-Amine)(POP)]PF6 (P3) (Phen-PyMethylene-Adam-Amine = ((5-phenylpyridin-2-yl)methylene)adamantan-1-amie, Methoxyl-Phen-PyMethylene-Adam-Amine = ((5-(4-methoxyphenyl)pyridin-2-yl)methylene)adamantan-1-amine, TriflMethyl-Phen-PyMethylene-Adam-Amine = ((5-(4-(trifluoromethyl)phenyl)pyridin-2-yl)methylene)adamantan-1-amine, POP=bis[2- diphenylphosphino ]-phenyl)ether) have been prepared and investigated. Incorporation of the bulky adamantyl group into the complexes can enhance the stability of the complexes. The different electron-donating/withdrawing groups such as –H, –OCH 3 , and –CF 3 substituents were functionalized onto the pyridine ring part of Schiff base ligands to tune the emission behavior of the resulting Schiff base Cu(I) complexes. All complexes exhibit the lowest energy metal-to-ligand charge transfer (MLCT) characters in 400–450 nm region showing a slight blue-shift of the absorption wavelengths in the order P3 > P1 > P2. Organe-red emissions in the region of 611-619 nm with photoluminescence quantum yields (PLQY) of 1.0–1.3% can be observed in the solid state. Additionally, the photophysical properties are also investigated theoretically using density functional theory (DFT) and time dependent DFT. [Display omitted] [ABSTRACT FROM AUTHOR]