Determination of the Inclusion Constants for the Inclusion Complexes between meso-Tetrakis (4-sulfonatophenyl) Porphyrin and Cyclodextrins by Three Methods

In this paper, the interactions of meso-Tetrakis (4-sulfonatophenyl) porphyrin (TPPS 4 ) and six cyclodextrins have been studied, respectively, by fluorescence spectroscopy, polarography and thin-layer chromatography. The inclusion constants of different methods are determined and the comparison of inclusion capacity of various cyclodextrins indicates that for the ionic cyclodextrins the charge interaction plays an important role in the inclusion procedure. The thermodynamic parameters of interaction imply that the inclusion process shows the enthalpy-entropy compensation effect. Cyclodextrin, being regarded as an artificial analogue of proteinoid of heme, provides a protective sheath for porphyrin. However, the TPPS 4 , encapsulated within this saccharid-coated barrier, its solubility is enhanced prominently, which exhibits that this interaction may modify the biological properties of TPPS 4 that owned the similar properties as hematoporphyrin.     

Study on the Supramolecular System of TAPP and Cyclodextrins by Spectroscopy

The ability of β-cyclodextrin (β-CD), γ-CD, hydroxypropyl-β-CD (HP-β-CD), trimethyl-β-CD (TM-β-CD), sulfurbutylether-β-CD (SBE-β-CD) and carboxymethyl-β-cyclodextrin (CM-β-CD) to break the aggregate of the meso-tetrakis(4-N-trimethylaminobenzyl)porphyrin (TAPP) and to form 2:1 inclusion complexes has been studied by absorption and fluorescence spectroscopy. The formation constants are calculated, respectively, by fluorimetry, from which the inclusion capacity of different CDs is compared and the inclusion mechanism of charged-β-CD (SBE-β-CD and CM-β-CD) is quite different from that of the parent β-CD. At lower pH, the complexation between TM-β-CD and H²TAPP²⁺ (the form of the diprotonated TAPP) hampers the continuous protonation of the pyrrole nitrogen of TAPP and the hydrophobic cavity may prefer to bind an apolar neutral porphyrin molecule. ¹HNMR data support the inclusion conformation of the porphyrin–cyclodextrin supramolecular system, indicating the interaction of the meso-phenyl groups of TAPP with the cavity of CDs. For this host–guest inclusion model, cyclodextrin being regarded as the protein component, which acts as a carrier enveloping the active site of heme prosthetic group within its hydrophobic environment, provides a protective sheath for the porphyrin, creating artificial analogues of heme-containing proteins. However, for TAPP, encapsulated within this saccharide-coated barrier, its photophysical and photochemical properties changed strongly.     

甲基苯丙胺标准物质的定值与不确定度分析

为了建立法庭科学毒品检测量值溯源体系,研制了甲基苯丙胺纯度标准物质。通过红外光谱、质谱法对甲基苯丙胺样品进行定性分析,优化并建立了高效液相色谱(HPLC)、差示扫描量热法(DSC)两种定值分析方法。采用热重分析法和电感耦合等离子体质谱法测定水分和无机离子的含量。通过均匀性与稳定性检验结果表明,甲基苯丙胺标准物质的均匀性良好,稳定性至少1年,同时对其进行了不确定度评定。研制的甲基苯丙胺标准物质的纯度为99.8%,扩展不确定度为0.2%(k=2)。     

A review of sample preparation methods for the pesticide residue analysis in foods

The pesticide residues in foods have received increasing attention as one of the most important food safety issues. Therefore, more strict regulations on the maximum residue limits (MRLs) for pesticides in foods have been established in many countries and health organizations, based on the sensitive and reliable analysis methods of pesticide residues. However, the analysis of pesticide residues is a continuing challenge mainly because of the small quantities of analytes as well as the large amounts of interfering substances which can be co-extracted with them, often leading to experimental errors and damage to the analytical instruments. Thus, extensive sample preparation is often required for the pesticide residue analysis for the effective extraction of the analytes and removal of the interferences. This paper focuses on reviewing the recent development in the sample preparation methods for the pesticide residue analysis in foods since 2006. The methods include: liquid-liquid extraction (LLE), supercritical-fluid extraction (SFE), pressurized-liquid extraction (PLE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), gel permeation chromatography (GPC), solid-phase extraction (SPE), molecularly imprinted polymers (MIPs), matrix solid-phase dispersion (MSPD), solid-phase micro-extraction (SPME), QuEChERS, cloud point extraction (CPE) and liquid phase micro-extraction (LPME), etc. Particularly their advantages, disadvantages and future perspectives will be discussed.     

三苄基氯化锡及其衍生物的合成

三苄基氯化锡最初用格氏法制得。Keiti等曾报道由锡和苄基氯直接制备,这时溶剂对反应的影响很大:用水作溶剂时得到三苄基锡;用甲苯作溶剂时得到二苄基二氯化锡;用正丁醇作溶剂时三苄基氯化锡的产率只有61％。在反应体系中加入KI、KBr或H_3PO_4等催化剂,三苄基氯化锡的产率也只有60％。本文用DMF作溶剂,AlCl_3-I_2作催化剂,并首次在反应体系中加入镁、锌、铝和钠等使副产物氯化亚锡还原成活性很高的金属锡,后者再与等基氯反应,可使三苄基氯化锡的产率提高到91.3％。文中还报导三种尚     

固态电解质中锂离子传输机理研究进展

Inorganic crystalline solid electrolytes exhibit excep tional room-temperature ionic conductivities, giving them the potential to enable all-solid-state lithium (Li) - ion batteries. Developing new high-performance electrolytes is one of the most critical challenges to realize solid-state batteries, which requires understanding how chemistry facilitates fast ionic conduction and what the Li-ion migration mechanism is in in organic solid electrolytes. In this review, we aim to summarize recent fundamental research progress in Li-ion transport, including crystal structure, behavior of ion migration (i.e., single-ion jump and multi-ions cooperative migration), and the relationship between ion migration and microstructure. Generally, ion transport in crystalline structure can be categorized into vacancy and non-vacancy mechanism. For Li-ion conduction, the migration can be achieved through single-ion hopping and collective diffusion mechanism. For single-ion hopping mechanism, the diffusivity is determined by the depth of potential well (activation energy) and lattice dynamics;whereas in the later mechanism Li-ion moving from high potential to low potential could partially offset the energy required for Li-ion moving from low potential to high potential. By studying the collective diffusion from the perspective of local structures, it is believed that collective diffusion in fast ion conductor originates from the local 野dual Li-S/O冶 structure units, which can be characterized by the 野nearest Li-Li distance冶. Next, the paradigm of ion transport in solids is summarized. It is pointed out that most ion conductors follow Meyer-Neldel rule, where the activation energy and pre-exponential factor are mutual compensating. As a result, a balance should be adapted between these two values to achieve high Li-ion conductivity. However, for some fast ion conductors, the relationship does not follow the Meyer-Neldel rule (i.e., anti-Meyer-Neldel rule). Therefore, the physical significance of anti-Meyer-Neldel rule should be understood to develop next-generation lithium ion conductors. In the end, future perspectives and open questions are proposed to design and develop high-performance inorganic solid electrolytes. © 2021 Chinese Chemical Society. All rights reserved.     

Cobalt and nitrogen atoms co-doped porous carbon for advanced electrical double-layer capacitors

Electrical double-laye r capacitors are widely concerned fo r their high power density,long cycling life and high cycling efficiency.However,their wide application is limited by their low energy density.In this study,we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon(CoAT-NC) material.Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix,which is benefit for improving electrical conductivity and density of states of the carbon material.Therefore,an enhanced perfo rmance is expected when CoAT-NC is served as electrode in a supercapacitor device.CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte.Furthermore,a good energy density of30 Wh/kg can be obtained in the organic electrolyte.