A comparative study on nonlinear optical properties of zinc porphyrins analogs: Coordination atoms and group effects

Abstract

Density functional theory (DFT) has been carried out to investigate the electronic characteristics, UV-VIS-NIR absorption spectra, and nonlinear optical (NLO) properties of two series of zinc porphyrin analogs (FPD-Nx and TPD-Nx, x = 0-4) with donor-π-donor frameworks. The design of these analogs is based on previously synthesized furan-linked zinc porphyrins (FPDs) and thiophene-linked zinc porphyrins (TPDs). It is noted that their electro-optical features are sensitive to the numbers of N-coordination atoms and the attached groups. A dramatic enhancement of static first and second hyperpolarizabilities (β 0 and γ 0 ) occurs when two furan/thiophene rings are attached to the zinc porphyrin. Among the two series, FPD-N3 and TPD-N3 have the largest β 0 values of about 7600 a.u. The static γ 0 values of these complexes range from 0.41 Â 10 6 to 1.79 Â 10 6 a.u. The FPD-Nx has a larger γ 0 value than the corresponding TPD-Nx, but the γ 0 value of FPD-N2 is close to that of TPD-N2. In the dynamic NLO process, the electro-optical Pockels effect, second harmonic generation, and electro-optic Kerr effect can be enhanced at the wavelength of 1907 nm.This study provides a new strategy for the experimental design of high-performance NLO materials.