Preparation and Evaluation of a Ferrocenediamide Bridge bis(β-Cyclodextrin)-Bonded Chiral Stationary Phase for HPLC

Ferrocene is a stable metallocene complex with aromatic high-electron π-conjugated system and sandwich structures. We first prepared and characterized a novel ferrocenediamide bridged bis(β-cyclodextrin) chiral stationary phase (FeCDP) to explore its chiral separation function. Its HPLC performance was systematically evaluated by basic, acidic, amphoteric and neutral chiral probes, including triazoles, profens, flavanones, amino acids and β-blocker drugs in reversed-phase and polar organic modes, respectively. The results showed that FeCDP successfully resolved 44 kinds of tested analytes (Rs?=?0.66–4.38), of which 36 were completely separated (Rs?≥?1.5). The best resolutions of different types, such as hexaconazole, ketoprofen, 3'-hydroxyflavanone, phenylalanine and arotinolol on FeCDP were reached at 3.06, 1.90, 4.38, 1.89 and 2.12 in a short time, respectively. Especially, FeCDP could completely resolve imazalil (Rs?=?1.97), ketoprofen (Rs?=?1.90), dansylated arginine (Dns-Arg, Rs?=?1.50), pindolol (Rs?=?1.42), bevantolol (Rs?=?1.41), which were very difficult to be resolved on the conventional CDCSPs. However, under optimal condition, the ordinary CDCSP could only separate 19 analytes with low resolutions (Rs?=?0.29–1.27). Compared with the reported similar stationary phases, the HPLC performance of FeCDP was also further improved. Based on the above comparison results, the satisfactory enantioselectivity of FeCDP may be mainly due to the fact that the “pseudo-cavity” composed of two CDs and a ferrocene diamide, could provide cooperative inclusion for analytes. Meanwhile, the large π-conjugated ferrocenediamide bridging group could also provide hydrogen bonding, π–π stacking, dipole–dipole and hydrophobic interactions, which may promote the chiral recognition effect of FeCDP. Bridge CD-CSP was a versatile chiral separation material in drugs analysis.

Graphical Abstract

     

基于氧化石墨烯气凝胶固相萃取柱检测有机磷农药北大核心CSCD

以氧化石墨烯气凝胶三维纳米材料作为固相萃取的吸附剂,结合高效液相色谱,对食品中的有机磷农药(辛硫磷、双硫磷、倍硫磷、杀螟硫磷)进行检测分析。首先,利用冷冻干燥的方式制备得到氧化石墨烯气凝胶,通过扫描电镜、红外光谱、比表面积吸附等一系列的实验手段对其形貌及物理特性进行了表征,证明其成功合成。从扫描电镜中可见石墨烯的层状褶皱结构,其表面积为740.51 m^(2)/g。然后,将氧化石墨烯气凝胶直接填充于固相萃取柱中,在未借助任何硅胶等基体的条件下进行萃取研究;通过单因素实验,系统研究了萃取和洗脱条件对有机磷农药萃取回收率的影响。结果显示,在上样体积15 mL、样品溶液pH值4、上样速率1.0 mL/min、洗脱剂1.0 mL乙腈的条件下萃取回收率最高。与商用的萃取材料进行比较,包括碳十八硅胶柱(C18)、阴离子交换柱(SAX)、氨基柱(-NH_(2))和硅酸镁柱(Florisil),氧化石墨烯气凝胶填充的固相萃取柱的萃取回收率有明显提高。实验考察了氧化石墨烯气凝胶直接填充的萃取柱的寿命,结果显示该萃取柱可以重复使用15次,可见解决了分散无基体支撑的石墨烯纳米片容易破碎、堵塞筛板的问题。与液相色谱联用建立分析方法,4种有机磷农药的线性范围较宽,辛硫磷、双硫磷和倍硫磷的线性范围为1~200μg/L,杀螟硫磷的线性范围为2~200μg/L,线性拟合良好(线性相关系数r^(2)≥0.9949),检出限为0.2~0.5μg/L,满足于我国和其他国家限定标准的检测。将该方法应用于实际样品,在苹果皮中未检测到有机磷农药,对其进行加标,回收率为70.5%~93.6%,相对标准偏差≤10.4%。     

Synthesis, crystal structure, and properties of the adduct of bis(O,O′-diisopropyl dithiophosphato)nickel(II) with pyridine [Ni(i-Pr2dtp)2(py)2]

A new adduct bis(pyridine)-bis(O,O-diisopropyl dithiophosphato-S,S)nickel(II), [Ni(i-Pr₂dtp)₂(py)₂] (dtp = dithiophosphate, py = pyridine) has been obtained by re-crystallization from CH₃COCH₃. The crystal and molecular structure of the title complex has been determined by X-ray crystallography. It crystallizes in the monoclinic system, space group P2₁/c, with lattice parameters a = 6.4890(13) Å, b = 16.386(3) Å, c = 14.830(3) Å, = 99.74(3)°, V = 1554.1(5) ų, and Z = 2. The crystal structure consists of discrete molecules of [Ni(i-Pr₂dtp)₂(py)₂], which displays a slightly distorted octahedral geometry for the NiS₄N₂ chromophore. Two O,O-diisopropyl dithiophosphate ions act as bidentate ligands with their S atoms coordinated to Ni atom. Each forms a four-membered chelate ring in the equatorial plane. The N atoms from two pyridine ligands are axially coordinated to the Ni atom. The Ni S bond distances are 2.4492(8) Å and 2.5711(9) Å, and the Ni bond distances are 2.127(3) Å. Thermal analyses show that the thermal decomposition of this adduct is so unstable that loss of two pyridine ligands begins at about 65°C. Electronic and IR spectra data is in agreement with the structural data.     

带旁通的管道中的声能流及传声损失Ⅱ：实验研究

实验证实了具有不同的旁通管长度及旁通面积的管道中传声损失及声能流的理论分析结果;对于单频噪声,三分之一倍频噪声及白噪声均有较好的降噪量,且降噪频带较宽。本文提出的\     

流动管道内利用旁通管反声降噪非线性问题的数值模拟

具有流动的管道内的降噪工作是很有用的工程实际问题,当噪声源很强时就成为非线性问题。本文提出了一种非线性方法,可用来数值计算有流动时分通管对强噪声源的降噪影响。难点是建立并求解了连接点处的流动关系。数值算例表明,这种方法对线性和非线性情况下有流动的管道内利用旁通管的反声降噪问题都可适用。     

Graphene oxide doped polyaniline for supercapacitors

A novel high-performance electrode material based on fibrillar polyaniline (PANI) doped with graphene oxide sheets was synthesized via in situ polymerization of monomer in the presence of graphene oxide, with a high conductivity of 10 S cm^?1 at 22 °C for the obtained nanocomposite with a mass ratio of aniline/graphite oxide, 100:1. Its high specific capacitance of 531 F/g was obtained in the potential range from 0 to 0.45 V at 200 mA/g by charge–discharge analysis compared to 216 F/g of individual PANI. The doping and the ratio of graphene oxide have a pronounced effect on the electrochemical capacitance performance of the nanocomposites.     

Synthesis and Structure of a CdI<Subscript>2</Subscript> Coordination Polymer with 1,1′-(1,4-Butanediyl)bis-1<Emphasis Type="Italic">H</Emphasis>-benzotriazole(bbbt)

Abstract  

In this article, solution reaction of cadmium iodide with organic multifunctional ligand 1,1′-(1,4-butanediyl)bis-1H-benzotriazole(bbbt) generated a 1D polymer [CdI₂ (bbbt) (CH₃OH)]_n 1, and the crystal structure has been determined (C₁₇ H₂₀ Cd I₂ N₆ O), Mr = 690.59 a = 10.032(2), b = 13.503(3), c = 16.706(3) ?, space group C2/c, Z = 4, and V = 2223.1(8) ?³. In 1 the tetrahedral coordination of Cd(II) and the conformation of bbbt ligand make it a wave-shaped structure.     

Preparation and Crystal Structural Study of a Novel Coordinated Polymer [HgI<Subscript>2</Subscript>(4-bped)<Subscript>2</Subscript>] (bped = bis(4-pyridyl)ethylene diamine)

Abstract  

A novel coordinated polymer [HgI₂(4-bped)₂] was synthesized through the reaction of bis(4-pyridyl)ethylene diamine and HgI₂ in mixed MeOH–THF (5:2). The crystal structural analysis indicated that the complex crystallized in a monoclinic space group P2₁/c, a = 10.8392(12), b = 19.841(2), c = 8.8279(10), β = 95.452(2), V = 1889.9(4) ?³, Z = 4. The complex possessed a novel three-dimensional supramolecular framework formed by hydrogen bonds among repeating [HgI₂(4-bped)]₂ dimeric units.     

Optimization of a microwave-coupled enzymatic digestion process to prepare peanut peptides

The best enzyme to prepare peanut peptides, papain, coupled with microwave irradiation was selected from five common proteases according to the results of the yield of peanut peptides [nitrogen solution index (NSI) in trichloroacetic acid (TCA), TCA-NSI] and the degree of hydrolysis (DH). The main factors that influenced the microwave-coupled enzymatic digestion method were optimized by response surface analysis. The optimal conditions obtained were as follows: microwave extraction time, 9.5 min; power, 600 W; substrate concentration, 4%; enzymatic reaction temperature, 50 °C; enzyme quantity, 6,500 U/g; pH, 7.1 (phosphate buffer, 0.05 mol/L). Under these conditions, TCA-NSI was 62.00% and DH was 25.89%, which is higher than that obtained with either protease hydrolysis or microwave hydrolysis alone.     

Conducting polymer composites with graphene for use in chemical sensors and biosensors

This review (with 79 references) summarizes the recent work on the development of chemical sensors and biosensors based on the use of composites made from conducting polymers (CPs) and graphene. Owing to the unique electrical, mechanical, optical, chemical and structural properties of CP and graphene, these kinds of composites have generated increasing interest in senor field. In this review, we first discuss methods for preparation of CP/GE composites by chemical, electrochemical, or physical methods including electrostatic interactions. We then cover aspects of the fabrication of modified electrodes and the performance of respective sensors with electrochemical, electronic or optical signal transduction. We then discuss sensors for the determination of inorganic and organic species, gases and vapors. We also review the state of the art in respective biosensors for hydrogen peroxide and glucose, for oligomers (DNA, RNA, and aptamers), for biogenic amines, NAD^+/NADH, cytochromes and the like, and in immunosensors. Finally, the perspective and current challenges of CP/GE composites for use in (bio)sensors are outlooked.