Simultaneous speciation analysis of inorganic nitrogen with the use of ion chromatography in highly salinated environmental samples

We present the development of a method for the simultaneous determination of inorganic nitrogen species in oxidized (NO₂^–, NO₃^–) and reduced (NH₄⁺) forms using ion chromatography with diode‐array detection (205, 208, and 425 nm, respectively). The oxidized forms were determined directly after the separation in the anion exchanger, while the reduced form was determined in the column hold‐up time after derivatization with the Nessler reagent. The use of an appropriate modifier (Seignette reagent) and mobile phase (NaCl) enabled the determination of inorganic nitrogen species in highly salinated environmental samples (water, sediments). Moreover, low detection limits were obtained of 0.04 mg/L for NH₄⁺ and 0.006 and 0.005 mg/L for NO₂^– and NO₃^–, respectively. The analysis of environmental samples indicated NH₄⁺ contents of up to 1161 ± 47 mg/kg and NO₃^– of up to 148 ± 6 mg/kg for sediment samples, as well as the NH₄⁺ concentrations of up to 0.98 ± 0.10 mg/L, NO₂^– of up to 24 ± 1 mg/L and NO₃^– of up to 20 ± 1 mg/L for water samples.     

Preparation and characterization of diethylnicotinamidium perchlorate

The title compound is the first example of N,N′-diethylnicotinamidium, [denaH]⁺, salt which has been characterized by X-ray analysis and IR spectra. [denaH]ClO₄ was obtained from the reaction mixture prepared from N,N′-diethylnicotinamide (dena) and Fe(ClO₄)₃ in ethanol without any addition of HClO₄. The proton required for protonation of dena is produced by hydrolysis of aquairon(III) cations. In the crystal structure, cations and anions are held together by ionic interactions. The cations are linked to each other by pyridinium-carbonyl N-H⋯O=C hydrogen bonds and an infinite linear chain along axis a is formed. Dedicated to Professor Milan Melník on the occasion of his 70th birthday     

Effect of temperature on the performance of proton batteries based on chitosan–NH4NO3–EC membrane

Membranes of chitosan-based proton conductor polymer electrolyte were prepared by dissolving chitosan powder, ammonium nitrate (NH₄NO₃) salt and ethylene carbonate (EC) plasticizer in acetic acid solution. The temperature dependence of the chitosan-based membrane system was found to obey the Arrhenius relationship. The sample with the highest conductance, 18 wt.% CA + 12 wt.% NH₄NO₃ + 70 wt.% EC (CA40N70E), also possesses the lowest activation energy. From linear sweep voltammetry (LSV) results, the membrane is electrochemically stable at a potential of 1.6–1.8 V and a temperature of 298–353 K. The cells were fabricated using zinc powder (Zn) + zinc sulfate heptahydrate (ZnSO₄·7H₂O) + acetylene black (AB) + polytetrafluoroethylene (PTFE)|CA40N70E|manganese (IV) oxide (MnO₂) + AB + PTFE. The open circuit voltages of the cells are decreases as temperature increases, the same trend as that obtained by LSV. The cell performance is excellent at 333 K, with discharge capacity of 42.7 mAh, internal resistance of 16.8 Ω, maximum power density of 14.6 mW cm⁻² and a short-circuit current density of 31.0 mA cm⁻². However, at temperatures above 333 K, decomposition of the membrane degraded the electrochemical properties of the cells.     

整体柱离子对色谱快速分析高氯酸盐

研究了用硅胶整体柱和直接电导检测的离子对色谱快速分析高氯酸盐的方法。实验采用Chromolith Speed ROD RP-18e色谱柱,以氢氧化四丁铵(离子对试剂) 邻苯二甲酸 乙腈(有机改进剂)为淋洗液,讨论了离子对试剂浓度、有机改进剂浓度、pH、色谱柱温度和流速对ClO4-保留时间的影响。确定最佳色谱条件为:0.25mmol/L氢氧化四丁铵 0.18mmol/L邻苯二甲酸 7%乙腈(pH5.5)作为淋洗液,柱温30℃,流速6.0mL/min。在此条件下,ClO4-的保留时间在1min之内。其它常见阴离子(Cl-、NO3-、SO42-和I-)不干扰测定。方法的检出限为1.56mg/L;工作曲线的线性范围是2.4~100mg/L;峰面积的相对标准偏差(RSD,n=5)为1.9%。将本方法应用于测定加标果汁和加标地下水中的ClO4-,加标回收率分别为98.2%和97.6%。     

Synthesis, structure and nuclease activity of copper complexes of disubstituted 2,2′-bipyridine ligands bearing ammonium groups

A series of Cu(II) complexes of disubstituted 2,2′-bipyridine bearing ammonium groups [Cu(L¹⁻⁴)₂Br]⁵⁺ (1–4, L¹ = [5,5′-(Me₂NHCH₂)₂-bpy]²⁺, L² = [5,5′-(Me₃NCH₂)₂-bpy]²⁺, L³ = [4,4′-(Me₂NHCH₂)₂-bpy]²⁺, L⁴ = [4,4′-(Me₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridyl) were synthesized, of which complexes 1 and 4 were structurally characterized. Both coordination configurations of Cu(II) ions can be described as distorted trigonal bipyramid. The interaction between all complexes and CT-DNA was evaluated by thermal-denaturation experiments and CD spectroscopy. Results show that the complexes interact with CT-DNA via outside electrostatic interactions and their binding ability follows the order: 1 > 2 > 3 > 4. In the absence of any reducing agents, the cleavage of plasmid pBR322 DNA by these complexes was investigated and the hydrolysis kinetics of DNA was studied in Tris buffer (pH 7.5) at 37 °C. Obtained pseudo-Michaelis–Menten kinetic parameters: 15.0, 13.6, 2.01 and 1.69 h⁻¹ for 1, 2, 3 and 4, respectively, indicate that complexes 1 and 2 exhibit very high DNA cleavage activities. According to their crystal data, the high nuclease activity may be attributed to the strong interaction of the metal moiety and two ammonium groups with phosphate groups of DNA.     

原位分解法制备免预硫化CoMoS／γ-Al2O3催化剂的表征及加氢性能研究

以钼酸铵、硫代乙酰胺为原料合成四硫代钼酸铵溶液,γ-Al2O3为载体,首先浸渍Co盐,再负载四硫代钼酸铵,制备负载钴钼盐的前体.通过考察不同状态助剂钴对催化剂活性的影响,确定金属态存在的助剂钴可以显著提高催化剂的活性.对此前体采用原位分解法制备硫化态CoMoS/γ-Al2O3加氢精制催化剂,并进行XRD、XPS和HRTEM等表征.以FCC柴油为原料,考察了催化剂的活性及稳定性.结果表明,该催化剂的活性组分与载体γ-Al2O3的相互作用较弱,MoS2的分散度较好,堆积层数较高,大部分的MoS2以II型的CoMoS相存在,与传统方法制备的催化剂相比,硫化态的CoMoS/γ-Al2O3加氢精制催化剂具有更高的脱硫性能,1100 h稳定性试验结果表明该催化剂的稳定性较好.     

Ferric Perchlorate Catalyzed One‐pot Synthesis of 1,2,3,4‐Tetrahydro‐2‐pyrimidinones and ‐thiones: an Expedient Protocol for the Biginelli Reaction

An efficient synthesis of 1,2,3,4-tetrahydro-2-pyrimidinones and -thiones using ferric perchlorate as the catalyst from an aldehyde, ethyl acetoacetate, and urea or thiourea in acetonitrile was described. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of full catalysis, good yields and short reaction time.     

Optical Urea Biosensor Based On Ammonium Ion Selective Membrane

ABSTRACT

An optical urea biosensor was developed by immobilizing an urease enzyme layer on a thin ammonium-selective polymer membrane. The ammonium optical membrane utilized dichlorofluorescein octadecyl ester (DCFOE) as anionic chromophore and nonactin as neutral ionophore. The urease layer was coated on the top of the ammonium layer by gelatin entrapment combined with glutaradehyde cross-linking. Hydrolysis of urea catalyzed by urease produced ammonium ion, which was extracted into the-polymer film to form complexes with nonactin. A proton was released which resulted in a color change of the optical membrane due to charge neutrality principle. The biosensor     

Ferric perchlorate-mediated radical reactions of [60]fullerene

Transition-metal-salt-mediated radical reactions of fullerenes have attracted extensive attention as a new and important method for fullerene functionalization. The application of relatively cheap and easily available ferric perchlorate (Fe(ClO 4 ) 3 ) to the synthesis of [60]fullerene (C 60 ) has demonstrated remarkable advantages and afforded a series of novel fullerene derivatives. In this review we present our recent progress in this area and summarize the reactions of C 60 with malonate esters, β-keto esters, nitriles, aldehydes/ketones, and arylboronic acids in the presence of Fe(ClO 4 ) 3 to afford the C 60-fused disubstituted lactones, C 60-fused hemiketal, C 60-fused dihydrofuran, C 60-fused oxazoles, C 60-fused 1,3-dioxolanes, and fullerenyl boronic esters. The possible reaction mechanisms for the above-mentioned reactions are also described in detail.