SYNTHESIS AND CHARACTERIZATION OF NOVEL SOL-GEL DOPED ORGANIC／INORGANIC HYBRID NONLINEAR OPTICAL MATERIALS

4-hydroxy-4 ‘-nitro azobenzene (NHA) and 4-amino-4 ‘-nitro azobenzene (DO3) were prepared respectively from p-nitrophenylamine as a precursor compound. Two kinds of doped organic/inorganic hybrid nonlinear optical (NLO) materials containing NHA and DO3 were synthesized by Sol-Gel process. The preparation and properties of two NLO materials were studied and characterized by FTIR, IH-NMR, UV-VIS, SEM, DSC and SHG measurements. The results show that the maximum doping amounts of NHA and DO3 in two doped hybrid NLO materials are 7.2(wt)% and ll.3(wt)% respectively, and the corresponding second-order NLO coefficients (d33values) are 2.91 ×l0^-3esu and 6.14×10 -8 esu. Two doped NLO materials have relatively good RT stability, after 90 days at RT the d33 values can maintain about 85% of their initial values, but after l0h at 100℃ can only maintain about 50% of their initial values. In this report, the reasons for high-temperature instability of doped materials were discussed, and the possible improvements were also suggested.     

Molecular view of charge exchange in ion–C60 collisions

We present a theoretical study of charge transfer in H⁺+C₆₀ and He²⁺+C₆₀ collisions using an extension of the molecular time‐dependent method of ion–atom collisions. Energy‐correlation diagrams have been evaluated for the corresponding (C₆₀–H)⁺ and (C₆₀–He)²⁺ quasi‐molecules. Single and double charge‐transfer cross sections in C₆₀+He²⁺ collisions are reported for the first time. The results show that double charge‐transfer cross sections are only one order of magnitude smaller than single charge‐transfer cross sections. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Study on the interaction among molecules and the determination of DNA by light scattering with a new type rhodanine derivative

In this paper the resonance Rayleigh scattering (RRS) and second-order scattering (SOS) spectrums of interaction between deoxyribonucleic acid (DNA) and 3-(4′-methylphenyl)-5-(2′-sulfophenylazo) rhodanine (4MRASP) in the environment of surface active substance sodium dodecyl sulfate (SDS) were reported. The light scattering intensity of 4MRASP was enhanced obviously and directly proportional to the concentrations of DNA when DNA was present. Based on this, two new determination methods of DNA were established with high sensitivity and selectivity, and the limits of detection were 8.00 and 1.07 ng mL⁻¹. They were applied to the determination of trace amounts of nucleic acid in synthetic and practical samples with satisfactory results. At last, the active mechanism among molecules was studied by ultraviolet spectrum, scattering spectrum and thermodynamics, which showed that the active force was changed from hydrophobic force to electrostatic force before and after SDS was added, and the mechanism of sensitization effect of SDS was proposed.     

Multi-way chemometric methodologies and applications: A central summary of our research work

Multi-way data analysis and tensorial calibration are gaining widespread acceptance with the rapid development of modern analytical instruments. In recent years, our group working in State Key Laboratory of Chemo/Biosensing and Chemometrics in Hunan University has carried out exhaustive scientific research work in this area, such as building more canonical symbol systems, seeking the inner mathematical cyclic symmetry property for trilinear or multilinear decomposition, suggesting a series of multi-way calibration algorithms, exploring the rank estimation of three-way trilinear data array and analyzing different application systems. In this present paper, an overview from second-order data to third-order data covering about theories and applications in analytical chemistry has been presented.     

Study of the influence of silver nanoparticles on the second-order scattering and the fluorescence of the complexes of Tb(III) with quinolones and determination of the quinolones

Quinolones (Qs) can form the complex with Tb(III) ion, and the intramolecular energy transfer from Qs to Tb(III) takes place when excited. And thus the characteristic fluorescence of Tb(III) ion was enhanced and the maximum fluorescence peak locates at 545 nm. The second-order scattering (SOS) peak at 545 nm also appears for the Tb(III)-Qs complexes with the exciting wavelength of 274 nm. When the silver nanoparticles were added to the Tb(III)-Qs system, the luminescence intensity at 545 nm greatly increased. And the relative intensity is proportional to the amount of Qs. Based on this phenomenon, a novel method for determination of quinolones has been developed by using a common spectrofluorometer to measure the intensity of fluorescence and SOS. The luminescence intensity is greatly enhanced by silver nanoparticles in the pH range 5.5-6.2. The calibration graphs for pipemidic acid (PPA) and lomefloxacin (LMFX) are linear in the range 2.0 × 10⁻¹⁰ to 1.0 × 10⁻⁵ and 1.0 × 10⁻⁹ to 1.0 × 10⁻⁵ mol L⁻¹, respectively. The limits of detection are 4.7 × 10⁻¹¹ mol L⁻¹ for PPA and 1.1 × 10⁻¹⁰ mol L⁻¹ for LMFX. The method was applied satisfactorily to the determination of the two quinolones (Qs) in tablet, capsule, urine and serum samples. The experimental results showed that it is the certain size and certain concentration of silver nanoparticles that can greatly enhance the fluorescence -SOS intensity.     

Simultaneous determination of metronidazole and tinidazole in plasma by using HPLC–DAD coupled with second-order calibration

<正>A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper.The second-order calibration method based on APTLD(alternating penalty trilinear decomposition) algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time.The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.     

Multivariate curve resolution in liquid chromatography—resolving two-way multi-component data using a Varimax extended rotation

The Varimax extended rotations (VER) have been proposed as a new method to mathematically resolve severely overlapped peaks in chromatographic experiments that produce bilinear data. VER employs a four-step procedure to determine the relative concentration and identity of the components that comprise a severely overlapped chromatographic peak. In the first step, the data are pre-processed to ensure that they are in a form suitable for multivariate curve resolution. The second step involves principal component analysis, which reduces the dimensionality of the data matrix while simultaneously retaining the information present in the data. In the third step, a new coordinate system is developed for the data using a Varimax rotation followed by a so-called extended rotation, which assists in identifying the so-called pure regions in the peak. Identifying these regions is crucial to rotating the concentration and spectral matrices towards a solution. The fourth step utilizes alternating least squares (ALS) to improve the estimates of the concentration and spectral profiles of each component. Results from real and simulated data are used to illustrate the efficacy and simplicity of the proposed method.     

含咔唑生色团的有机芳香杂环分子的二阶非线性光学性质

采用密度泛函理论B3LYP/6-31G^*方法, 对一系列含咔唑生色团的有机芳香杂环分子进行结构优化, 并采用有限场(FF)和含时密度泛函理论(TD-DFT)方法在6-311G^**水平上探讨了体系的二阶非线性光学(NLO)性质和电子光谱. 结果表明, 咔唑取代基推或拉电子能力的改变和引入芳香杂环对研究分子的极化率α和二阶NLO系数β值都有较大影响. 当取代基分别连有拉电子硝基和推电子羟基, 以及引入呋喃杂环都可以使体系分子的β值随分子的最大吸收波长λ_max的增大而减小(蓝移). 该系列化合物兼具有很大的二阶非线性响应与良好的透光范围, 避免了“非线性-透光性”矛盾, 可能在非线性材料领域中有很大的潜在应用价值.     

Determination of the second-order H NMR parameters for the aromatic protons in 4-fluoroaniline and application to the analysis of the H NMR spectra for the aromatic protons in N-(4′-fluorophenyl)succinamic acid and in N-(4′-fluorophenyl)-3,3-difluorosuccinamic acid

Four studies of the ¹H NMR spectrum for the aromatic protons of 4-fluoroaniline between 1958 and 1974 give three very different solutions to the second-order, AA′BB′X, spectrum. A re-evaluation of the second-order spectrum was done at 300 MHz. Simultaneous simulations of the ¹H NMR spectrum and ¹⁹F NMR spectrum for 4-fluoroaniline were done using WINDNMR-Pro, and a new set of parameters for the six coupling constants was obtained from the optimized simulations. This new set of parameters was used as a basis to evaluate the AA′BB′X spectrum for the aromatic protons in N⁴-(4′-fluorophenyl)succinamic acid and in N⁴-(4′-fluorophenyl)-3,3-difluorosuccinamic acid by simultaneous simulations of the ¹H NMR spectrum and ¹⁹F NMR spectrum for each using WINDNMR-Pro. Formation of the amide bond results in small, but significant, changes in the values for the set of parameters in both molecules. These results confirm that second-order analyses as an AA′BB′X system are required for derivatives of 4-fluoroaniline, rather than first-order analyses that have been used in previous reports.     

Determination of Matrine and Oxymatrine in Radix Sophorae Flavescentis by Resonance Rayleigh Scattering,Second-order Scattering and Frequency Doubling Scattering Technique

In 0.1 mol/L HCl medium, 12-tungstophosphoric(TP) acid reacted with matrine(Mat) and oxymatrine(Oxy) to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering(RRS), second-order scattering(SOS) and frequency doubling scattering(FDS) appeared and their intensities were enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS were located at 370, 670 and 390 nm, respectively. The increments of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range. Based on this, the method for the determination of matrine and oxymatrine has been established. It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result. The reaction mechanism and reasons of RRS enhancement were discussed.