Organophosphorus π-conjugated materials: the rise of a new field

The synthesis and electronic properties of new linear organic π-conjugated systems incorporating phosphole rings are described. Well defined α,α′-(phosphole-thiophene) oligomers possess low HOMO-LUMO gaps and their optical and electrochemical properties can be tuned via chemical modifications of the P-atoms. The physical properties of these compounds make them valuable materials for OLED’s. The coordination ability of phosphole-based dipoles has been exploited for the synthesis of efficient multipolar NLO-phores. Lastly, phospholes have been used for the synthesis of assemblies exhibiting through-bond interaction between two π-systems via P-P σ-skeletons.     

Second-order nonlinear optical properties of side-chain liquid crystalline polymers studied by second harmonic generation from thin films

The two independent elements of the second-order nonlinear optical susceptibility tensor of a range of contact poled, donor–acceptor substitued side-chain polymers are reported. The susceptibilities were measured by second harmonic generation from thin films, typically less than 0.5 μm thick, at a fundamental wavelength of 1064 nm. The largest value was χ = 2.64 pm/V which is three times greater than the χ value of KDP and was measured in a nitrobenzylidene side chain, polyhydroxystyrene polymer with an eleven unit alkyl chain spacer attaching the side group to the backbone. Typical susceptibility values obtained were χ～0.3 pm/V and X⁽²⁾₃₃～1 pm/V. The coherence lengths of the materials, which lay in the range 4–12 μm, were measured at 1064 nm by the maker fringe technique using thick, wedge-shaped samples.     

Doped Sol-Gel Films for Silica-on-Silicon Photonic Components

Further expansion of optical communication systems depends strongly on the development of cheap component technologies for functions such as switching, demultiplexing and amplification. Silica-on-silicon is increasingly recognised as the best approach to low cost integrated optics for such applications, but so far the functionality is limited. The purpose of NODES, a basic research collaboration sponsored by the European Union under the programme ESPRIT, has been to examine the application of sol-gel to a highly functional silica-on-silicon technology. In particular, the project has investigated film processing and characterisation, rare-earth doping for amplification, and semiconductor nanocrystallite doping for nonlinear functions. This paper presents the background and context to this work, summarises the technical results obtained, and discusses requirements and challenges for successful application of sol-gel in photonics.     

苯并[b]萘并[2'''',3'''':5,6][1,4]二噻英并[2,3-i]噻蒽-5,7,9,14,16,18-六酮的合成及其三阶非线性光学性能

以1,4-萘醌为原料,合成了含硫的醌构稠杂环化合物苯并[b]萘并[2',3':5,6][1,4]二噻英并[2,3-i]噻蒽-5,7,9,14,16,18-六酮(4),其结构经1H NMR和IR确证.采用波长为800 nm,脉宽为80 fs的Ti:Sapphire飞秒激光,运用双光束简并四波混频法测定了4的三阶非线性光学性能,结果表明,4的三阶非线性光学极化率χ(3),非线性折射率n2,分子二阶超极化率γ和响应时间分别为2.89×10-13 esu, 5.31×10-12 esu, 3.14×10-31 esu和101 fs.并分析了4的分子结构对其三阶非线性光学性能的影响.     

Spectrophotometric and titrimetric determination of gallium in minerals and ores using semimethylthymol blue

The composition, overall stability constant and molar absorptivity of the chelate of gallium(III) ion with semimethylthymol blue, SMTB, were determined spectrophotometrically in acetate buffer (pH 4.5–5). A violet Ga(SMTB) chelate was formed with logarithmic overall stability constant of 18.0±0.1 (I=0.1) and molar absorptivity of 4.25×10⁴l mol^–1cm^–1 (_max 580 nm). SMTB is proposed as a new reagent for the spectrophotometric determination of micro-molar amounts of gallium(III). The colour development depends on time, temperature, pH and buffer species. The interference of different cations, anions and organic acids on gallium(III) determination was also investigated. Beer's law was obeyed for 3.5–31.3 gGa(III)/25ml (0.14–1.25 g ml^–1). SMTB was used for the spectrophotometric determination of gallium in different grade minerals and ores and the results were of acceptable error and relative standard deviation. Comparison between the two suggested methods and atomic absorption spectrometry for Ga(III) determination was carried out.     

The pockels coefficient of new polymers for nonlinear optics and its time dependence after poling,compared with dielectric measurements

Epoxy polymers with donor–acceptor type side groups were synthesized for application in nonlinear optics. The stability of the Pockels coefficient was measured in thin films after poling. The relaxation times and their temperature dependence seem to be correlated with dielectric measurements. Guest–host systems (polystyrene and polymethylmethacrylate with dimethylaminonitrostilbene) were investigated for comparison.     

Synthesis of Calix[4]arene Derivatives with NLO Properties

The new chromophore compounds with NLO properties were prepared by Knoevenagel condensation from forrnyl or diformyl calix[4/arene and isophorone derivatives in the presence of piperidine and acetic acid, respectively. In these chromophore calix[4]arenes, the ring locked trienes were employed as the conjugation bridge and electron acceptor in D-π-A units. The NMR spectra demonstrated that they existed in a cone conformation and consequently non-conjugated D-π-A units could be oriented at nearly the same direction.     

The Synthesis of Third—order Optical Nonlinear Organic Polyheterocyclic Materials

Synthesis of the third-order nonlinear materials:bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4-naphthaquinone. The materials exhibit larger third-order nonlinear optical susceptibilities χ.     

Synthesis and characterization of meso-ferrocenylethynyl 5,15-diphenylporphyrins

A series of four meso-ferrocenylethynyl (5,15-diphenylporphyrinato)nickel(II) derivatives have been synthesized by Sonogashira coupling reactions. Three of these compounds contain the electron-withdrawing groups including -CHO, -CHC(CN)₂, and -CCC₆H₄NO₂ at the remaining meso position, with a view to preparing push-pull chromophores, in which ferrocene serves as the electron donor. All the new compounds have been characterized spectroscopically and the molecular structure of one of these porphyrins (compound 11) has also been determined. The studies show that although the ferrocenylethynyl group can extend the π system of the central porphyrin core, the cyclopentadienyl rings of ferrocene are almost orthogonal to the porphyrin ring. This hinders ferrocene serving as a good electron donor in these systems.