Synthesis, crystal structure and equilibrium studies on the bidentate amine adducts of bis(S-methyl-β-N-(4-methyloxyphenyl) methylendithiocarbazide)nickel(II) complex

The crystal structure of the 1,10-phenanthroline bis(S-methyl-β-N-(4-methyloxyphenyl)methylendithiocarbazide)nickel(II) adduct, (Ni(SN)₂phen) [SN = S-methyl-β-N-(4-methyloxyphenyl)methylendithiocarbazide, PHEN = phenanthroline], has been determined by single crystal X-ray diffraction. The nickel atom is in an octahedral environment, surrounded by two chelating SN ligands and one chelating phen molecule. The nitrogen atoms from phen are in the cis configuration. The other chelating diamines adducts of the parent complex (Ni(SN)₂) were also studied, where the chelating diamnies are 5-nitro-1,10-phenanthroline(NO₂phen), 2,2′-bipyridine (bipy), 4,4′-methyl-2,2′-bipyridine (Mebipy). The equilibria were determined by UV-vis spectrometry in dichloromethane. The coordination ability of the added ligands were influenced by substitute groupings and steric factors. From the structure and addition equilibrium studies, the possible addition mechanisms are also discussed.     

HCl-NaCl-C3H8O3-H2O体系溶液热力学性质

在恒定丙三醇质量分数x=0．1的条件下，测定了无液接电池（A）和电池（B）的电动势根据电池（A）电动势确定了丙三醇和水混合溶剂中的Ag－AgCl电极的标准电极电势，讨论了HCl的迁移性质；由电池（B）测得的电动势计算了HCl在该体系中的活度系数γA，计算的结果表明，对于所讨论的体系，在溶液中总离子强度保持恒定，HCl的活度系数服从Harned规则．在溶液组成恒定时，IgγA是温度倒数1／T的线性函数，讨论了混合物中HCl的相对偏摩尔焓及介质效应．     

Determination of Tiopronin in Human Plasma by SPE then Reversed-Phase HPLC–UV

An accurate, simple and sensitive method based on reversed-phase high-performance liquid chromatography with UV detection has been developed for determination of tiopronin (TP) in human plasma. TP in plasma was reacted with p-bromophenacyl bromide (p-BPB) to give the TP-p-BPB adduct and this derivative was then extracted from the plasma on a silica gel cartridge. Potential interfering compounds were removed by washing with water, and the TP-p-BPB adduct was then eluted with acetonitrile. The organic phase obtained was evaporated to complete dryness under a stream of nitrogen. The residue was dissolved in acetonitrile and this solution was injected on to a reversed-phase ODS HPLC column. The mobile phase was usually the ternary mixture acetonitrile–water–trifluoroacetic acid, 40:59.88:0.12 (v/v). The retention times of TP-p-BPB and the internal standard adduct were 14.4 and 17.9 min, respectively. No interfering peaks were encountered in several blank plasma samples examined. The limit of detection for TP was 12 ng mL^?1. Extraction recovery exceeded 70%. The calibration plot for the TP derivative was linear in the range 40?4000 ng mL^?1, regression coefficient 0.9989, and the coefficient of the variation of the points of the calibration plot was below 10%. The method was validated appropriately and successfully applied to the determination of TP in human plasma.     

Amperometric glucose biosensor based on electrodeposition of platinum nanoparticles onto covalently immobilized carbon nanotube electrode

A new amperometric biosensor for glucose was developed based on adsorption of glucose oxidase (GOx) at the gold and platinum nanoparticles-modified carbon nanotube (CNT) electrode. CNTs were covalently immobilized on gold electrode via carbodiimide chemistry by forming amide linkages between carboxylic acid groups on the CNTs and amine residues of cysteamine self-assembled monolayer (SAM). The fabricated GOx/Au_nano/Pt_nano/CNT electrode was covered with a thin layer of Nafion to avoid the loss of GOx in determination and to improve the anti-interferent ability. The immobilization of CNTs on the gold electrode was characterized by quartz crystal microbalance technique. The morphologies of the CNT/gold and Pt_nano/CNT/gold electrodes have been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the gold, CNT/gold, Pt_nano/gold and Pt_nano/CNT/gold electrodes has also been studied by amperometric method. In addition, effects of electrodeposition time of Pt nanoparticles, pH value, applied potential and electroactive interferents on the amperometric response of the sensor were discussed.

The enzyme electrode exhibited excellent electrocatalytic activity and rapid response for glucose in the absence of a mediator. The linear range was from 0.5 to 17.5 mM with correction coefficient of 0.996. The biosensor had good reproducibility and stability for the determination of glucose.     

固定化酶反应器及其在蛋白质组研究中的应用

综述了近年来国内外酶固定化载体的研究进展,侧重于无机材料和有机聚合物材料上的固定化酶方法;此外,也介绍了固定化胰蛋白酶反应器与分离系统联用在蛋白质样品分析中的应用,并展望了固定化酶反应器的研究方向及其在蛋白质组中的应用前景。     

Effects of Calcination Temperature on the Acidity and Catalytic Performances of HZSM-5 Zeolite Catalysts for the Catalytic Cracking of n-Butane

The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature.The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.     

Sunlight-activated AlFeO3/TiO2 photocatalyst

A nanocomposite photocatalyst composed of AlFeO₃ and TiO₂ is prepared, and characterized through X-ray diffraction. Application of the nanocomposite for the photodegradations of eosin dye and methyl orange gives an improved photoactivity compared with TiO₂-only nanomaterials. The optimal concentration of AlFeO₃ in the composite is about 1.0 wt% under UV excitation, and 9.0 wt% under sunlight excitation for the improved photoactivity. Furthermore, this nanocomposite is more active for eosin photodegradation if natural sunlight rather than UV is used. This may be due to the reason that adding AlFeO₃ nanoparticles into TiO₂ matrix can promote the separation of photogener-ated charge carriers, and extend the photoresponse of TiO₂ toward visible region, which results in an increase in the solar energy utilization efficiency.     

Synthesis,structure and the e.s.r. spectrum of the mixed-valence molybdovandate Na2(NH4)4[(VIVVV8Mo)O28] · 10H2O

The mixed-valence molybdovanadate compound Na₂(NH₄)₄[V^IVV^V ₈Mo)O₂₈] · 10H₂O [Vanadata(6-)tetradeca--oxotetra-₃-oxodi-₆-oxoheptaoxo(oxomolybdate) nonatetrammonium disodium, decahydrate] has been synthesized from sodium molybdate(VI) dihydrate and sodium metavanadate dihydrate in aqueous solution by adding NH₂OH · HCl. The molecular structure has been determined by X-ray diffraction and is based on the isopolydecavanadate structure. The molybdate atom is crystallographically disordered over 6MO₆ octahedral sites. The e.s.r. spectrum clearly indicates that one vanadium atom has the oxidation number +4.     

High resolution spectral analysis of 13CH3OH in the excited torsional states

In this work, we have extended our previous analysis of the Hamiltonian of 13C substituted methanol to include a large number of spectral lines involving the second excited torsional state using an improved model. The data set consisted of 2529 Fourier transform and microwave transitions with the rotational angular momentum J < or = 10, K < or = 6 and n < or = 2 (with 336 MW lines). The data set was fitted with the new Hamiltonian model to derive the molecular parameters. The results indicate that the model developed for the other methanol species (CH3OH, CH3(18)OH and CH3OD) is also valid for the C-13 substituted species. The results will allow the energy levels of the molecule to be calculated for higher torsional levels above the internal rotational barrier with improved precision and allow the analysis to be carried out for more excited torsional states.     

Intercalating lithium into the lattice of silver nanoparticles boosts catalytic hydrogenation of carbon–oxygen bonds

Coinage metal nanoparticles with high dispersion can serve as highly efficient heterogeneous catalysts. However, owing to their low melting point, poor thermal stability remains a major obstacle towards their application under reaction conditions. It is a common practice to use porous inorganic templates such as mesoporous silica SBA-15 to disperse Ag nanoparticles (NPs) against aggregation but their stability is far from satisfactory. Here, we show that the catalytic activity for hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) over Ag NPs dispersed on SBA-15 silica can be further promoted by incorporation of alkali metal ions at small loading, which follows the inverse order of their cationic size: Li⁺ > Na⁺ > K⁺ > Rb⁺. Among these, 5Ag₁–Li_0.05/SBA-15 can double the MG yield compared to pristine 5Ag/SBA-15 under identical conditions with superior thermal stability. Akin to the effect of an ionic surfactant on stabilization of a micro-emulsion, the cationic charge of an alkali metal ion can maintain dispersion and modulate the surface valence of Ag NPs. Interstitial Li in the octahedral holes of the face center packed Ag lattice is for the first time confirmed by X-ray pair distribution function and electron ptychography. It is believed that this interstitial-stabilization of coinage metal nanoparticles could be broadly applicable to multi-metallic nanomaterials for a broad range of C–O bond activating catalytic reactions of esters.

Coinage metal nanoparticles with high dispersion can serve as highly efficient heterogeneous catalysts.