D-π-A push-pull chromophores based on N,N-Diethylaniline as a donor for NLO applications: Effects of structural modification of π-linkers

Three metal-free organic compounds based on N,N-Diethylaniline as a donor, and 2-(3-cyano-5,5-dimethylfuran-2(5H)-ylidene)malononitrile as an acceptor of electrons with the D-pi-A architecture were investigated theoret-ically using DFT, LC-DFT and TD-DFT techniques for future usage as NLO materials. The effect of changing the pi-linker of the parent compound M1 on the electronic, photophysical characteristics and the nonlinear optical response has been extensively studied and discussed. M1-M3 exhibit a band gap (Egap) in the 1.51 to 1.85 eV range with lambda abs of 600 to 900 nm. The results indicate that M3 possesses excellent polarization characteristics of the first total hyperpolarizability beta tot at 15.48 x 10-28 esu associated with a low Egap at 1.51 eV. Examining the NBO, the DOS, and the TDM reveals that charge separation occurred following photoexcitation, and the electrons were migrated from the donor to the acceptor group.