Experimental and theoretical study of the regioisomers of N,N -dimethyl (((phenylethynyl)phenyl)ethynyl) aniline

Abstract

5 regioisomers of N,N-dimethyl(((phenylethynyl)phenyl)ethynyl)aniline (nDPEA) were synthesized by Sonogashira cross-coupling reaction and well characterized. The spectroscopic properties of these regioisomers were studied and discussed. nDPEAs 1b and 1d show shorter λ_abs and lower Φ_F due to meta- branching disrupts the π-electron conjugation. nDPEAs 1c and 1e show shorter λ_abs because of their steric effects. Based on the high Φ_F values of 1a, 1c and 1e, the π-electrons of these nDPEAs are delocalized over the whole molecules. These results are consistent with the theoretical calculations. Time dependent density functional theory computations were performed with the B3LYP or CAM-B3LYP for the identification of vertical transitions in 1a-1e. The predicted and observed absorption spectra of 1a-1e are well consistent.