2,4-Dioxo(dimercapto)-1,5-benzodiazepino-13-couronne-2, Nouveau Macrocycle Complexant de L'ion Ag +

We describe herein the synthesis of new macrocycles 5 et 6 derived from 1,5-benzodiazepine-2,4-dione in a heterogenous media using phase transfer catalysis conditions. A crystallographic study by x-ray of 5 was carried out to confirm the structure suggested; moreover the macrocycle 6 presents chelating properties with respect to the ion Ag + easily observed by IR and UV spectroscopies.     

MECHANISM OF THE REACTION OF DIPHENYL N-BROMOSULFILIMINE WITH SULFIDES,PHOSPHINES AND TERTIARY AMINES

Abstract

The mechanism of the reactions of diphenyl N-bromosulfilimine (I) with such nucleophiles as sulfides, phosphines and tertiary amines was investigated. In the presence of water, (I) reacts with sulfides or phosphines to afford the corresponding sulfoxides or the phosphine oxides in moderate yields; however, the reaction with tertiary amine gave only the N-t-aminosulfilimine derivative. The effect of ring size in the reaction with cyclic sulfides suggests that the reaction proceeds via initial bromine transfer from the nitrogen atom to the sulfur atom of the cyclic sulfides followed by S_N2 type substitution of bromide on the sulfur atom of the cyclic sulfide with the sulfilimino group. The phosphine oxide obtained in the reaction of (I) with optically active methyl n-propyl phenyl phosphine was racemized but retained a small portion of the optical activity. In the case of tertiary amines, even 1,4-diazabicyclo-(2,2,2)-octane (DABCO), in which the back side of the nitrogen atom is blocked, reacted smoothly to afford the corresponding ammonium salts, suggesting the reaction to be of S_N2 type on the nitrogen atom of the sulfilimine.     

一种新的褪色光度法测定Cr^3＋的方法研究

提出了一种褪色光度法测定Cr~(3+)的新方法。新的叠氮试剂3-(苯偶氮苯)-1-三氮烯苯甲酸钠(PTBAS)在NaOH-Na_2B_4O_7缓冲液中,在表面活性剂OP的存在下,与Cd~(2+)反应后形成一种橙红色的络合物。测定Cd~(2+)时,当有微量Cr~(3+)共存时,络合物吸光度值明显降低,利用这种现象可以间接测定Cr~(3+)。测得Cr~(3+)的表观摩尔吸光系数ε=1.12×10~5,线性范围为0～0.4μg·ml~(-1)。方法选择性很高,很多常见离子不干扰测定,可直接用于水样中Cr~(3+)的测定。     

Optimization of Electrochemical Total Creatine Kinase Biosensors Based on Three‐Au‐Electrode

For point‐of‐care examination, total CK (creatine kinase: adenosine‐5‐triphosphate‐creatine phosphotransferase, EC 2.7.3.2) biosensors were developed and optimized. The biosensors were fabricated with three‐Au‐electrode system modified with polyvinylpyridine‐osmium‐wired horseradish peroxidase (PVP‐Os‐HRP) redox polymer film. The reagents were separately immobilized on the single layer biosensor and double layer biosensor which contained lens paper layer and the surface layer of the working electrode. The mediator, the working potential, the structure of working electrode and the stabilizer agent were studied. The biosensor with double reagent layer showed good stability at room temperature (≥2 months) and the biosensor with single reagent layer had excellent response signal (a sensitivity of 11 nA L U^?1 cm^?2).     

N,O-Benzylidene Acetal Dipeptides (NBDs) Enable the Synthesis of Difficult Peptides via a Kinked Backbone Strategy

Proteins with highly hydrophobic regions or aggregation-prone sequences are typically difficult targets for chemical synthesis at the current stage, as obtaining such type of peptides via solid-phase peptide synthesis requires sophisticated operations. Herein, we report N,O-benzylidene acetal dipeptides (NBDs) as robust and effective building blocks to allow the direct synthesis of difficult peptides and proteins via a kinked backbone strategy. The effectiveness and easy accessibility of NBDs have been well demonstrated in our chemical syntheses of various challenging peptides and proteins, including chemokine, therapeutic hormones, histone, and glycosylated erythropoietin.     

基础化学教学实验室试剂和仪器的科学细化管理

介绍了厦门大学化学国家级实验教学示范中心基础化学实验(一)实验室在试剂和仪器科学细化管理方面的一些具体做法,如试剂的排序存放、计划补充、优化使用及仪器的"五防"和"三位一体"管理模式。通过对试剂、仪器一系列规范、有序、科学的细化管理,节约了试剂用量,减少了废物排放量,保证了干净整洁的实验环境;培养了学生良好的实验习惯,保证了仪器的正常运行及获得准确的实验数据,并提高了仪器的使用寿命,为实验教学的顺利开展提供了有力的保障。希望能为国内高校化学教学实验室相关方面管理提供可借鉴的经验。     

Determination of Trace Silver( Ⅰ ) in Basic Aqueous Solution by Electrochemiluminescence of a New Reagent 6-(2-Hydroxy-4-Diethylaminophenylazo)-2,3-Dihydro-1,4-Phthalazine-1,4-Dione

The electrochemiluminescence (ECL) of a new reagent 6- (2-hydroxy- 4 diethy laminophenylazo)-2,3-dihydro-1 ,4-phthalazine-1,4-dione (HDEA) in a basic aqueous so lution was studied by using the apparatus designed by ourselves. Trace amounts of silver ( Ⅰ ) shows a significant effect on the efficiency of light emission of HDEA during a positive trigonometrical wave pulse was exerted on the solution. The linear relationship between the light intensity and the concentration of silver( Ⅰ ) occurs in the range of 5. 0×10-8 to 3. 0×10-8 mol/L Ag(Ⅰ ) in a medium of KOH-KCl-HDEA (pH= 12. 8). The detection limit of the method is 2. 0×10-8 mol/LAg( Ⅰ ), and the r. s. d. for 1.0×10-7 mo)/L Ag ( Ⅰ ) is 5%. Of 21 metal ions concerned, only nickel( Ⅱ ), cerium( Ⅳ ) and cobalt( Ⅱ ) interfere the silver detection seriously; Ⅰ and Br also have some interference.     

Design of a Bilateral Disulfurating Reagent for Unsymmetrical Polysulfidation

In this study, we designed a bilateral disulfurating reagent via S−S motif “snip and stitch” processes, allowing diverse functional groups to be bridged via S−S bonds. The reagent is readily synthesized in high yield using a one-step reaction from easily available starting materials and is air-stable. With this reagent, diverse electrophiles including inactivated alkyl Cl/Br/I/OMs and benzyl chloride were sequentially installed on either side of the S−S motif. Natural products, agrochemicals, and pharmaceuticals can be successively cross-linked with S−S bonds. Notably, the disulfurating reagent can be used in cyclic disulfide synthesis. At last, some desired products of this work showed good antibacterial activities, which could be employed as novel candidates to control plant pathogenic bacteria.     

Tetrazole Diversification of Amino Acids and Peptides via Silver-Catalyzed Intermolecular Cycloaddition with Aryldiazonium Salts

Selective structural modification of amino acids and peptides is a central strategy in organic chemistry, chemical biology but also in pharmacology and material science. In this context, the formation of tetrazole rings, known to possess significant therapeutic properties, would expand the chemical space of unnatural amino acids but has received less attention. In this study, we demonstrated that the classic unimolecular Wolff rearrangement of α-amino acid-derived diazoketones could be replaced by a faster intermolecular cycloaddition reaction with aryldiazonium salts under identical practical conditions. This strategy provides an efficient synthetic platform that could transform proteinogenic α-amino acids into a plethora of unprecedented tetrazole-decorated amino acid derivatives with preservation of the stereocenters. Density functional theory studies shed some light on the reaction mechanism and provided information regarding the origins of the chemo- and regioselectivity. Furthermore, this diazo-cycloaddition protocol was applied to construct tetrazole-modified peptidomimetics and drug-like amino acid derivatives.