Interpreting the First-Order Electronic Hyperpolarizability for a Series of Octupolar Push–Pull Triarylamine Molecules Containing Trifluoromethyl

Abstract

In this present paper, we investigate the relationship between the dynamic first-order hyperpolarizability (DFH, or βHRS) of a triarylamine core bearing two 3,3′-bis(trifluoromethyl)phenyl arms and the nature of a third group containing distinct electron-withdrawing strength (H < CN < CHO < NO2 < Cyet < Vin). For that, we have combined hyper-Rayleigh scattering (HRS) experiments with picosecond pulse train at 1064 nm and quantum chemical calculations at the density functional theory (DFT) level. The βHRS values exhibited pronounced enhancement from 56 × 10–30 cm5/esu (EWG = CN) up to ∼400 × 10–30 cm5/esu (EWG = Vin) due to the increase in the degree of donor–acceptor charge transfer concomitant with the intensification of the resonance enhancement effect observed when the scattered photon (2ω = 532 nm) approaches, in energy, the lowest energy band of chromophores. Furthermore, our experimental results suggest that the CF3 group has a significant effect on the βHRS, since we observed a considerable increas...