锆掺杂TiO_2光催化降解2-CEES和DMMP的原位红外与固体核磁研究

在国内率先将金属离子掺杂型纳米TiO_2用于化学毒剂(CWAs)洗消领域,制备了系列浓度的锆掺杂纳米TiO_2(Zr-TiO_2).为了从分子水平上认识Zr-TiO_2对CWAs的消毒机制,结合原位红外(in-situ FTIR)与固体核磁共振(SSNMR)技术,研究了掺杂前后样品表面2-CEES和DMMP的反应机理和动力学变化.结果显示:制备样品中无尿素残留,且掺杂浓度为10.05%的Zr-TiO_2光催化活性最佳;与掺杂前相比,该样品对2-CEES和DMMP的光催化降解速率加快,但反应机制不变:对DMMP的降解主要通过同时发生P-OCH3氧化和P-CH3分解,对2-CEES则依次通过C—Cl键断裂、C—S键断裂和S原子氧化完成降解,两种模拟剂在反应过程中均未生成有毒中间产物.通过研究,建立了适用于化学毒剂洗消领域的原位在线分析方法,掌握了模拟剂的光催化消毒反应机理、产物与动力学规律,为今后实毒样品的测试打下了基础.     

Analyses of trace amounts of dyes with a new enhanced sensitivity FTIR spectroscopic technique: MU-ATR (metal underlayer ATR spectroscopy)

The identification of organic dyes is a challenging task in all the fields such as the forensic and conservation sciences, especially in cases where the amount of sample is extremely small. In this paper we propose a new enhanced FTIR method (MU-ATR metal underlayer ATR spectroscopy), which we believe is the first of its kind, for the analysis of a few ng of dyes. With this method, dyed fiber micro-extracts can be analyzed using a commercial FTIR microscope with a fixed incident angle, obtaining the same separation between the different classes of dyes investigated as we obtained analyzing pure dyes in transmission mode.     

Investigation of structural,rheological and thermal properties of PMMA/ONi-Al LDH nanocomposites synthesized <Emphasis Type="Italic">via</Emphasis> solvent blending method: Effect of LDH loading

This article addresses the synthesis of organically tailored Ni-Al layered double hydroxide (ONi-Al LDH) and its use in the fabrication of exfoliated poly(methyl methacrylate) (PMMA) nanocomposites. The pristine Ni-Al LDH was initially synthesized by co-precipitation method and subsequently modified using sodium dodecyl sulfate to obtain ONi-Al LDH. Nanocomposites of PMMA containing various amounts of modified Ni-Al LDH (3 wt%-7 wt%) were synthesized via solvent blending method to investigate the influence of LDH content on the properties of PMMA matrix. Several characterization methods such as X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), rheological analysis, differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA), were employed to examine the structural, viscoelastic and thermal properties of PMMA/OLDH nanocomposites. The results of XRD and TEM examination confirm the formation of partially exfoliated PMMA/OLDH nanocomposites. The FTIR results elucidate that the characteristic bands for both pure PMMA and modified LDH are present in the spectra of PMMA/OLDH nanocomposites. Rheological analyses were carried out to examine the adhesion between polymer matrix and fillers present in the nanocomposite sample. The TGA data indicate that the PMMA nanocomposites exhibit higher thermal stability when compared to pure PMMA. The thermal decomposition temperature of PMMA/OLDH nanocomposites increases by 28 K compared to that of pure PMMA at 15% weight loss as a point of reference. In comparison with pure PMMA, the PMMA nanocomposite containing 7 wt% LDH demonstrates improved glass transition temperature (T _g) of around 3 K. The activation energy (E _a), reaction orders (n) and reaction mechanism of thermal degradation of PMMA/OLDH nanocomposites were evaluated using different kinetic models. Water uptake capacity of the PMMA/OLDH nanocomposites is less than that of the pure PMMA.     

New metal complexes with diclofenac containing 2-pyridineethanol or 2-pyridinepropanol: synthesis,structural, spectroscopic,thermal properties,catechol oxidase and carbonic anhydrase activities

Four new neutral diclofenac-based complexes, [Co(dicl)2(2-pyet)2] 1, [Ni(dicl)2(2-pyet)2] 2, [Cu2(dicl)2(2-pyet)2] 3, and [Cu2(dicl)2(2-pypr)2] 4 have been synthesized and characterized by elemental analysis, FT-IR, thermal analysis. Complexes 1, 3, and 4 have also been characterized by X-ray single-crystal structural analysis. The compounds of Co(II) and Ni(II) have octahedral geometry with two diclofenac and two 2-pyridineethanol ligands in the coordination sphere. The compounds of Cu(II) have square-pyramidal geometry and Cu(II) ions are linked via oxygens to the bridging 2-pyridineethanol or 2-pyridinepropanol ligands. The Δν values acquired by FT-IR are in agreement with the single XRD data. Studies on the thermal properties are reported and the complexes are stable to 196, 216, 215, and 201 °C in air, respectively. Two dinuclear Cu(II) complexes have demonstrated catalytic activity on oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone showing saturation kinetics at high substrate concentrations. The diclofenac complexes are investigated as inhibitors of the human cytosolic isoforms hCA I and II. The complexes are good as hCA I inhibitors (Kis of 1.52–55.06 μM) but only moderately efficient as hCA II inhibitors (Kis of 0.23–5.61 μM).     

Synthesis,characterization, and crystal structure analysis of 2-(2-hydroxy-3-methoxyphenyl)-1-(4-chlorophenyl)-4,5-diphenyl-1h-imidazole

The substituted imidazole C₂₈H₂₁ClN₂O₂, was prepared via multicomponent reactions and the product crystallized using dimethylformamide. The structure of the compound was established by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-visible, proton nuclear magnetic resonance spectroscopy, and single-crystal X-ray diffraction. The molecule is crystallized in the tetragonal crystal system with the space group P4₃2₁2 and with unit cell parameters a = 12.246(4) Å, b = 12.246(4) Å, c = 31.781(2) Å, and Z = 8. The molecular and crystal structures of the title molecule are stabilized by the intramolecular interactions, O-H···N and C-H···N, and intermolecular interaction, C-H···O.     

Effect of the Pretreatment of Lipase with Organic Solvents on its Conformation and Activity in Reverse Micelles

The activity and conformation of Chromobacterium viscosum lipase-pretreated with various organic solvents were investigated. The pretreatment of lipase led to a substantial increase of enzyme activity in AOT (sodium bis [2-ethyl -1-hexyl] sulfosuccinate)/isooctane/water reverse micelles. Among the organic solvents used, n-hexane was found to be most effective. It was observed that higher hexane content with shorter agitation time and vice versa had almost the same effect on the initial activity of lipase. The kinetic study showed that the Michaelis constant (K _m) and the substrate adsorption equilibrium constant (K _ad) were reduced by the pretreatment of lipase with hexane, whereas the change in the maximum reaction rate (V _max) was insignificant. The two spectroscopic techniques (Fluorescence spectra of lipase encapsulated in RMs and Fourier transform infrared [FTIR] spectra of lipase powders) were performed to detect possible conformational changes in the enzyme caused by the pretreatment. A correlation between the maximum fluorescence intensity and the activity of treated lipase was found as a function of agitation time. The FTIR spectrum of lipase showed a new shape peak corresponding to 1,500 cm⁻¹ as a result of pretreatment with organic solvents.     

H NMR and IR study of temperature-induced phase transition of negatively charged poly(N-isopropylmethacrylamide-co-sodium methacrylate) copolymers in aqueous solutions

¹H NMR and IR spectroscopies were used to investigate the temperature-induced phase transition behaviour of poly(N-isopropylmethacrylamide-co-sodium methacrylate) [P(IPMAAm/MNa)] copolymers, containing in aqueous solutions negatively charged MNa units (i = 1-10 mol%), and the obtained results were compared with those obtained for poly(N-isopropylmethacrylamide) (PIPMAAm) homopolymer. For PIPMAAm/H₂O solution, IR spectra indicate that the transition temperatures for the hydrophilic CO groups are slightly higher (by ∼ 2 K) in comparison with hydrophobic CH₃ groups. The decreasing values of phase-separated fraction p_max and the decrescent hysteresis during gradual heating and cooling, both with increasing content of MNa units i in the copolymer, show that for copolymers with i ? 5 mol% the globular-like structures formed at temperatures above the respective LCST are rather porous and disordered with relatively low degree of polymer-polymer hydrogen bonding. While for P(IPMAAm/MNa) copolymers with i ? 5 mol% most water molecules are expelled from globular structures, for i < 5 mol% a certain portion of water (HDO) molecules is rather tightly bound in globular structures; at the same time no releasing process was detected for the bound water even for 90 h.     

Structural and electrical properties of polyvinyl alcohol (PVA):Methyl cellulose (MC) based solid polymer blend electrolytes inserted with sodium iodide (NaI) salt

This paper studies the structural and electrical properties of solid polymer blend electrolytes based on polyvinyl alcohol (PVA) and methylcellulose (MC) incorporated with sodium iodide (NaI). The polymer electrolyte films were assembled through a solution casting technique. The host matrix, which is doped with different NaI salt concentrations between 10 and 50 wt%, utilizes the most amorphous blend compositions (60 wt% Polyvinyl alcohol and 40 wt% methylcellulose). The structural behaviour of the electrolyte films was examined utilizing X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) techniques. The semi crystalline nature of PVA:MC with inserted NaI was derived from the X-ray diffraction studies, while the XRD analysis suggests that the highest ion conductive sample displays the minimum crystalline nature. The interaction between polymer blends and inserted salt was conceived from the FTIR investigation. Shifting of peaks and variation in the intensity of FTIR bands was detected. To investigate the structural properties and calculate the degree of crystallinity of the films, the (XRD) technique was employed, while electrical impedance spectroscopy (EIS) was utilized for studying the conductivity of the samples. In order to comprehend all of the electrical properties of the ion-conducting systems, the EIS outcome of each electrolyte was matched with Equivalent Electrical Circuits (EEC) s. Ion transport parameters including mobility, carrier density and diffusion are well assessed for the samples and the dielectric properties were compared with the conductivity measurement. At lower frequencies, the dielectric constant was elevated and dielectric loss was detected. Loss tangent and electric modulus plots were used to study the relaxation nature of the samples. The highest ambient temperature conductivity of PVA loaded 50 wt% of NaI was determined to be 1.53 × 10⁻⁵ S/cm. The loss tangent relaxation peak shifts towards high-frequency side which indicates the decrease of relaxation time and faster ion dynamics.     

Design of plasticized proton conducting Chitosan:Dextran based biopolymer blend electrolytes for EDLC application: Structural,impedance and electrochemical studies

In this work, for the use of an electrical double-layer capacitor (EDLC) device applications, the fabrication and characterization of solid polymer electrolytes (SPEs) based on chitosan-dextran (CS-DN) blended polymer doped and plasticized with ammonium thiocyanate (NH₄SCN) and glycerol are studied, respectively. The Fourier transform infrared (FTIR) spectroscopy method has been used to investigate the structural behavior of electrolytes. It was observed that the FTIR bands are shifted and decreased in their intensities with the increased glycerol plasticizer content and it results in the complex formation. According to the electrical impedance spectra (EIS), the electrolyte incorporated with high contents of plasticizer (42 wt%) revealed the highest ionic conductivity of (3.08 × 10⁻⁴ S/cm). The electrical equivalent circuits (EEC) were used to investigate the circuit elements of the electrolytes further. Increasing glycerol plasticizers verified an improvement in ions density number (n), mobility (μ), and diffusion coefficient (D). The transference number measurements (TNM) indicated that the predominant charge carriers in the conduction process are ions where the (t_ion) is 0.95. According to the linear sweep voltammetry (LSV) study, the uppermost conducting sample was found to have sufficient anode stability with a breakdown voltage of 1.9 V that can be used in electrochemical devices. The absence of peaks in the cyclic voltammetry (CV) demonstrated that the charge storage mechanism within the constructed EDLC is fully capacitive. Based on this finding, the starting specific capacitance (C_s), energy density (E_d), and power density (P_d) have been identified to be 118F/g, 13.2 Wh/kg, and 1560 W/kg, respectively. Throughout its 100 cycles, the equivalence series resistance ESR value was between 53 and 117 Ω.     

Vibrational Spectroscopic Analyses and Imaging of the Early Middle Ages Hemp Bast Fibres Recovered from Lake Sediments

Fourier Transform Infrared (FT-IR) spectroscopy and imaging combined with hierarchical cluster analysis (HCA) was applied to analyse biochemical properties of Early Middle Ages hemp (Cannabis sativa L.) bast fibres collected from lake bottom sediment of lake Słone. The examined plant macrofossil material constitutes residues of the hemp retting process that took place in the 7th–8th century. By comparison of three samples: untreated isolated bast fibres, and fibres incubated overnight at 4 and 37 °C, we were able to mimic the retting conditions. Using FT-IR qualitative and semi-quantitative assessment of the primary polysaccharides content, total protein content, and their spatial distribution was performed within the hemp fibres. The concentration of cellulose remained vastly unchanged, while the concentration of lignin and pectin was the highest in the untreated sample. The spatial distributions of compounds were heterogeneous in the untreated and 4 °C-incubated samples, and homogenous in the specimen processed at 37 °C. Interestingly, a higher amide content was detected in the latter sample indicating the highest degree of enzymatic degradation. In this study, we show that the spectroscopic methods allow for a non-destructive evaluation of biochemical composition of plant fibres without preparation, which can be an appropriate approach for studying ancient plant remains.