Synthesis, spectroscopic and DFT studies of copper(I) complexes inserting the electron-donating groups into pyridine-imidazole ligands vis an acetylide linker.

• Copper (I) complexes were functionalized with various electron-donating groups. • The enhanced light absorption abilities were achieved vis an acetylide linker. • Complexes have the emission wavelengths of 579–590 nm and quantum yields of 8.40–15.1%. • The nature of the emitting state was discussed using the theoretical calculations. The three Cu(I) complexes [Cu(POP)(N^N)]PF 6 , N^N = 2-(1 H -imidazol-2-yl)-5-(p -tolylethynyl)pyridine (P1), 2-(1 H -imidazol-2-yl)-5-((4-methoxyphenyl)ethynyl)pyridine (P2), 4-((6-(1 H -imidazol-2-yl)pyridin-3-yl)ethynyl)- N , N -diphenylaniline (P3), were prepared and characterized. The different electron-donating groups such as methylphenyl, methoxyphenyl, and diphenylamine substituents were functionalized onto the pyridine ring part of the diimine ligands through an acetylide linker to enhance the light-absorption abilities, giving the larger light-absorption ability and red-shifted absorption bands for the investigated Cu(I) complexes. Yellow emissions in the range of 579–590 nm with quantum yields of 8.40–15.1% can be observed for all complexes at room temperature. The photophysical properties were further explained by DFT and TDDFT methods. [ABSTRACT FROM AUTHOR]