PREPARATION AND SECOND-ORDER OPTICAL NONLINEARITY OF NOVEL PHENOXYSILICON NETWORKS BY SOL-GEL PROCESS

Four phenoxysilicon networks for nonlinear optical (NLO) applications were designed and prepared by an extended sol-gel process without additional H2O and catalyst. All poled polymer network films possess high second-order nonlinear optical coefficients (d(33)) Of 10(-7)similar to 10(-8) esu. The investigation of NLO temporal stability at room temperature and elevated temperature (120 degreesC) indicated that these films exhibit high d(33) stability because the orientation of the chromophores are locked in the phenoxysilicon organic/inorganic networks.

A Theoretical Study of Nonlinear Second-Order Optical Properties of Substituted Silanes

On the basis of ZINDO method and according to the sum over states(SOS) expression, the program is devised for the calculation of nonlinear second order optical susceptibilites β ijk and studying how different substituents on the phenyl ring attached to the atom silicon influence on the nonlinear second order optical properties of substituted silane series of molecules. The properties of (CH 3) 3Si? ?has been studied particularly. The effect of the length of silica chains on the calculated values has been studied too. The regularity summarized from the calculated results has been explained micromechanically.

THE SYNTHESIS OF NEW POLED CROSSLINKED POLYMETHACRYLATES AND THEIR SECOND ORDER NONLINEAR OPTICAL PROPERTIES

Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophore content: 25 mol %). During thermal poling process the anhydride reacts with the epoxy group and the resulting crosslinked network structure will stabilize the second harmonic generation in the poled film. The second harmonic generation of the poled film shows a maximum with the variation of composition this is presumed to be due to the effects of the increasing of concentration, orientation order as well as orientation stability of chromophore groups during crosslinking.

SECOND ORDER NONLINEAR OPTICAL PROPERTIES OF DICYANOPYRAZINES

Second order nonlinear optical active 2,3-dichloro-5,6-dicyanopyrazine (DCDCP) and its monoamine-substituted derivatives had been synthesized. Their facile synthesis, high melt point, high incidence af substantial SHG activity and increased transparency inthe blue and near infrared make this class compounds appealling for further investigation.

Modulation of the Second Order Nonlinear Optical Properties of Helical Graphene Nanoribbons Through Introducing Azulene Defects or/and BN Units

The current study has obtained excellent potential nonlinear optical(NLO)materials by combining density functional theory methods with sum-over-states model to predict the second order NLO properties of helical graphene nanoribbons(HGNs)through introducing azulene defects or/and BN units.The introduction of these functional groups deforms the pristine HGN(compression or tension)and enhances obviously the static first hyperpolarizability(〈β0〉)of system by up to two orders of magnitude.The tensor components along the helical axis of HGNs play a dominant role in the total〈β0〉.The azulene defects and the BN units polarize the pristine HGN to different degrees,and the azulenes and contiguous benzenes are involved in the major electron excitations with significant contributions to〈β0〉but the BN units are not.The BN-doped chiral HGNs have good kinetic stability and strong second order NLO properties(6.84×10^(5)×10^(−30) esu),and can be a potential candidate of high-performance second order NLO materials.The predicted two-dimensional second order NLO spectra provide useful information for further exploration of those helicenes for electro-optic applications.

Density Functional Studies on Isonicotinato Lead(II) Complex [Pb(C_5H_4NCOO)_2]

The title compound of isonicotinato lead（Ⅱ） [Pb（C5H4NCOO）2] has been optimized at B3LYP/LANL2DZ level of theory and calculated results show that the lead（Ⅱ） ion adopts 4-coordinate geometry. Atomic charge distributions indicate that during forming the title compound, each isonicotinic acid ion transfers -0.452 e to lead（Ⅱ） ion. The electronic spectra calculations show that there exist two absorption bands and the electronic transitions are mainly derived from the contribution of intraligand π→π^＊ transition and ligand-to-metal charge transfer （LMCT） transition. The thermodynamic properties of the title compound at different temperatures have been calculated and corresponding relations between property and temperature have also been obtained. The calculation of the second order optical nonlinearity was carried out, and the molecular hyperpolarizability was 3.62365^＊10^-30 esu.

Theoretical and Experimental Studies on the Metal Complex of Diethylenetriamino-trioxo-molybdenum(VI) [MoO_3(NH_2C_2H_4NHC_2H_4NH_2)]

For diethylenetriamino-trioxo-molybdenum（Ⅵ）, density functional theory （DFT） method calculations of the structure, atomic charge distributions, electronic spectra, natural population analyses and thermodynamic properties at different temperatures have been performed by B3LYP method using LANL2DZ, CEP-121G and CEP-31G basis sets, respectively. The calculated results show that B3LYP/LANL2DZ method can best reproduce the molecular structure. The atomic charge distribution analyses indicate that during forming the complex, the ligand of diethylenetriamine donates negative charges to MoO3 and these charges are accepted by molybdenum（Ⅵ） atom as well as three oxygen atoms. The electronic spectra calculations indicate that B3LYP/ LANL2DZ results are nearest to experimental data among the three methods and electronic transitions are mainly derived from the contribution of bands π→π^＊. The calculation of the second order optical nonlinearity was carried out, and the molecular hyperpolarizability was 0.7881^＊10^30 esu.