Feng Ji-Kang

Theoretical study of the nonlinear optical properties of C74 and Ca@C74

Abstract Using density functional theory and the semiempirical ZINDO method, we have investigated the equilibrium geometries, electronic spectra, and the second and third hyperpolarizabilities of C 74 and the metallofullerene Ca@C 74 . Theory predicts that Ca@C 74 has greater stability than C 74 and that the UV–Vis spectrum of Ca@C 74 shifts to the blue. Both species possess relatively large β μ values and thus are promising as nonlinear optical materials.

Theoretical studies on the one- and two-photon absorption properties of azulenylporphyrins and azulene-fused porphyrins

The electronic structures, one-photon absorption (OPA) and two-photon absorption (TPA) properties of the azulenylporphyrins and azulene-fused porphyrins have been comparatively studied by using DFT/B3LYP/6-31G(d) and the ZINDO/SDCI method. With the number of azulenyl groups increasing, the OPA wavelengths of all molecules are red-shifted in 400{600 nm and the two-photon absorption cross section is gradually enlarged. The azulene-fused structures facilitate an expanding conjugated area and increasing TPA cross section. The origin of TPA properties of studied compounds is studied with a two-level model. In summary, the azulene-fused porphyrins exhibit strong two-photon absorption.

Molecular design and theoretical investigation into one- and two-photon absorption properties of two series of cyclometalated platinum (II) complexes

We have theoretically investigated two series of cyclometalated Pt(II) complexes, a series [Pt (C, N, N) Cl] and b series [Pt (C, N, Npyrazolyl) Cl]. The geometrical and electronic structures are calculated at the ECP60MWB//6-31G*(H, C, Cl, N, S) basis set level using DFT method; one-photon absorption (OPA) properties are calculated by using both TDDFT and ZINDO methods and two-photon absorption (TPA) properties are obtained with the ZINDO/SOS method. The resonance integrals parameters (βsp and βd) for Pt are adjusted to −1 and −28.5 eV, respectively, to make max OPA wavelength calculated by ZINDO closest to the experimental data and TDDFT results. The calculated results indicate the molecule 2b ([Pt (Cnaphthyl, N, Npyrazolyl) Cl]) has the biggest potential as outstanding TPA materials because (i) the TPA properties of b series are more outstanding in IR wavelength range, the molecules in b series have good transparencies and possess 1-pyrazolyl-NH that is also available for another metal coordination (e.g., dimerization) and chemical interactions; (ii) when C is Cnaphthyl in the C, N, N ligand of cyclometalated Pt(II) complexes, the molecules have the best conjugation effect and the best TPA properties.

Theoretical Study on the Two-Photon Absorption Properties of Pyrazole Aluminum Compounds

An extensive series of pyrazole aluminum compounds containing an Al_2N_4 center as a pseudo-conjugated system were theoretically investigated for their one-photon absorption and two-photon absorption(OPA and TPA) properties by density functional theory(DFT) and Zerners intermediate neglect of differential overlap(ZINDO) methods.The results indicate that pyrazole aluminum compounds are good TPA materials and that the TPA maximal absorption cross-section(δ_(max)) can reach 2860.1 GM(1 GM=10~(-50) cm~4·s·photon~(-1)).By incorporating electron-acceptors in the central core,aπ-conjugated bridge and terminal groups,the OPA and TPA properties can be modulated.This research provides strategies for the enhancement of molecular TPA in the target region.The origin of the largeδ_(max) of some of the studied molecules was determined using a three-level energy model.We conclude that an increase in the intramolecular charge transfer can enhanceδ_(max).Moreover,the pyrazole aluminum compounds behave in a similar manner to pyrazaboie chromophores in terms of linear optical,and TPA properties and they possess an increasedδ_(max) to some extent.