羟丙基田菁胶的结构研究

本文用IR、~(13)C-NMR、~1H-NMR、MS、元素分析手段对田菁胶原粉和环氧丙烷反应的合成样品进行系统地结构研究,证明样品为羟丙基型半乳甘露聚糖类,其主结构与田菁胶原粉一致,并用~1H-NMR法测定了羟丙基田菁胶的醚化度(D.S).     

The metal complexes of new Schiff bases containing phosphonate groups and catalytic properties for alkane oxidation

In this study, two new salicylidene phosphonate ligands (HL¹ and HL²) and their metal complexes (Cu²⁺, VO²⁺ and La³⁺) were synthesized and characterized by spectroscopic and analytical methods. The molecular structure of the ligand HL¹ was determined by single‐crystal X‐ray diffraction study. In the structure of the ligand, there is an intramolecular phenol‐imine hydrogen bond. The synthesized compounds exhibit only one emission maximum upon excitation at 270–295  nm range. Complexation of the Schiff base ligands with metal ions did not cause a considerable quenching effect. Finally, the complexes prepared were used as catalysts in cyclohexane oxidation under microwave irradiation. The complexes showed high conversion rates (> 90%) for cyclohexane oxidation; however, poor selectivity was observed for all complexes. The La³⁺ complexes showed better selectivity for cyclohexane → cyclohexanol transformation with about 45% selectivity.     

Effect of synthesis routes on the electrochemical performance of Li[Ni0.6Co0.2Mn0.2]O2 for lithium ion batteries

The cathode-active materials, layered Li[Ni_0.6Co_0.2Mn_0.2]O₂, were synthesized by two different routes: spray-drying and solid-state methods. The influence of synthesis routes on the crystal structure, morphology, and electrochemical performance of the samples were characterized by X-ray diffraction, scanning electron microscope, and charge/discharge test. As a result, both samples showed a typical hexagonal structure with a single phase. However, the difference in synthesis route resulted in the difference in morphology and electrochemical performance, such as reversible capacity and the rate capability. The initial discharge capacity of sample synthesized by spray-drying method at room temperature and 50 °C were 173.1 and 181.2 mAh g^?1, respectively, which were higher than those of 166.8 and 177.5 mAh g^?1 for sample synthesized by solid-state method. The cycling performance was also evaluated. Sample synthesized by spray-drying method exhibits a higher discharge capacity and better cycling performance than those prepared by solid-state method, even at elevated temperature.     

SYNTHESIS AND CHARACTERIZATION OF SOME DITHIOCARBOHYDRAZONES

ABSTRACT

Three bisthiocarbohydrazones had been synthesized and characterized. The structures of the three compounds were determined by elemental analysis, IR, MS, ¹H NMR and ¹³C NMR. The crystal structure of one of the compounds was determined by X-ray single crystal diffraction techniques.     

Cryochemical modification,activity, and toxicity of dioxidine

Dioxidine nanoparticles are prepared via cryochemical modification of the pharmacopoeial dioxidine substance. The form of the cryomodified dioxidine is characterized by data from ¹H NMR spectroscopy; X-ray diffraction analysis; such thermal analytical methods as TG and DSC; low-temperature argon adsorption; and transmission electron microscopy. It is shown that the cryomodified samples are synthesized in the form of dioxidine nanocrystals 50–300 nm in size, with a crystal structure differing from that of the initial pharmacopoeial substance. The prepared cryomodified dioxidine nanoparticles inhibit the growth of E. coli 52, S. aureus 144, M. cyaneum 98, and B. cereus 9 better than the initial pharmacopoeial substance, and have comparable chronic toxicity.     

Study on the structure of epoxidized <Emphasis Type="Italic">trans</Emphasis>-1,4-polyisoprene synthesized by heterogeneous and homogeneous method using <Superscript>13</Superscript>C NMR<Superscript>1</Superscript>

A structure study of epoxidized trans-1,4-polyisoprene (ETPI) synthesized by heterogeneous method is carried out using ¹³C-NMR. In this paper, we present a new analytical method for assigning overlapping ¹³C-NMR signals of ETPI in terms of the triad of trans-1,4-isoprene and epoxidized units. The monomer unit sequence distributions in epoxidized fractions of heterogeneous ETPI are detected and compared with those of ETPI synthesized by homogeneous method. Results prove that in less epoxidized polymer (16%), monomer unit sequence distributions in epoxidized fractions of heterogeneous ETPI are randomly distributed. And when the epoxy content is higher than 23%, a certain degree of block structure appears. What’s more, with the increasing of epoxy content, more block structure appears.     

CURING AND RHEOLOGICAL BEHAVIOR OF VINYL ESTER RESINS PREPARED IN THE PRESENCE OF TERTIARY AMINES

Vinyl ester resins V₁, V₂ & V₃ of acid value (～6 mg KOH g^?1 solid) were synthesized using bisphenol-A epoxy and acrylic acid in the presence of triethyl-, tripropyl- and tributyl-, amines in 210, 270 and 340 minutes, respectively. The synthesized resins were characterized by FTIR spectroscopy and a new peak at 2360 cm^?1 was observed which is due to attachment of amines to resin structure by hydrogen bond. The curing behavior of synthesized resin containing 40% styrene (w/w) and 2% benzoyl peroxide was studied using DSC technique and found to be affected by presence of amines. Activation energy and frequency factor for the curing reaction increases from 14 Kcal mol^?1 to 23 Kcal mol^?1. Rheological behavior of resins containing 40% styrene was studied using a Haake Rotovisco RV20 viscometer, and viscosity was found to increase with shear rate up to 200 sec^?1. The average values of activation energy at constant shear stress (6-15 Pa) were 12.94, 13.20, 13.70 Kcal mol^?1 for V₁, V₂ and V₃, respectively. The activation energy at constant shear rate decreases with an increase in the shear rate.     

New sensing materials of molecularly-imprinted polymers for the selective recognition of Chlortetracycline

As a result of the stressful conditions in aquaculture facilities there is a high risk of bacterial infections among cultured fish. Chlortetracycline (CTC) is one of the antimicrobials used to solve this problem. It is a broad spectrum antibacterial active against a wide range of Gram-positive and Gram-negative bacteria. Numerous analytical methods for screening, identifying, and quantifying CTC in animal products have been developed over the years. An alternative and advantageous method should rely on expeditious and efficient procedures providing highly specific and sensitive measurements in food samples. Ion-selective electrodes (ISEs) could meet these criteria. The only ISE reported in literature for this purpose used traditional electro-active materials. A selectivity enhancement could however be achieved after improving the analyte recognition by molecularly imprinted polymers (MIPs).Several MIP particles were synthesized and used as electro-active materials. ISEs based in methacrylic acid monomers showed the best analytical performance according to slope (62.5 and 68.6 mV/decade) and detection limit (4.1 × 10⁻⁵ and 5.5 × 10⁻⁵ mol L⁻¹). The electrodes displayed good selectivity. The ISEs are not affected by pH changes ranging from 2.5 to 13. The sensors were successfully applied to the analysis of serum, urine and fish samples.     

IR and NMR Study of the Structure of Dextran Polyaldehyde

The structure of samples of dextran polyaldehyde synthesized at various pH was studied by IR and ¹³C NMR spectroscopy and PM3 semiempirical quantum-chemical method.     

Non-destructive compositional analysis of sol–gel synthesized lithium titanate (Li2TiO3) by particle induced gamma-ray emission and instrumental neutron activation analysis

Lithium titanate, one of the important tritium breeding materials in D–T based fusion reactor under ITER programme, was synthesized through sol–gel route. For chemical quality control of finished product, it was necessary to quantify the lithium and titanium contents. As this ceramic sample is difficult to dissolve, non-destructive analytical methods are preferred for compositional analysis. In the present work, two non-destructive nuclear analytical methods namely particle induced gamma-ray emission (PIGE) using proton beam and instrumental neutron activation analysis (INAA) using reactor neutrons were standardized for the determination of lithium and titanium concentrations, respectively and applied to eleven samples of lithium titanate. To the best of our knowledge, Li quantification in lithium titanate sample is being reported for the first time using PIGE. For quantifications of Li and Ti, 478 keV prompt gamma-ray from ⁷Li (p, p′γ) ⁷Li and 320 keV gamma-ray from ⁵⁰Ti (n,γ) ⁵¹Ti were measured, respectively, by high resolution gamma-ray spectrometry. The PIGE and INAA methods were validated using several synthetic samples containing lithium and titanium, respectively. Concentrations of lithium and titanium and Li/Ti mole ratios were evaluated and compared with the stoichiometric concentration of Li₂TiO₃.