Silica Sulfuric Acid‐Catalyzed Five‐component Efficient Synthesis of Five‐Substituted Tetrahydropyridines

A highly atom‐economic one‐pot synthesis of five‐substituted tetrahydropyridines via a five‐component condensation of two equivalents of aromatic aldehyde, two equivalents of aromatic aniline, and one equivalent of β‐keto ester catalyzed by silica sulfuric acid is reported. In this reaction, up to five new bonds and one new ring were formed in one pot with water as the only one by‐product.     

Transition Metal Acetate Promoted Syntheses of Some New N‐Heterocycles by Multicomponent Reactions

The intermolecular cyclization reactions of N‐tosyl‐ethylenediamine with glyoxal promoted by transition metal acetate at different ratios gave three N‐heterocyclic compounds. The ligand in compound 1 contains one N‐heterocycle, which is formed by a one‐pot three‐component reaction. In compound 2 , two imidazolidine rings and one piperazine ring are fused together to form a tricyclic skeleton by a one‐pot five‐component reaction. Two 1,3,6‐triazabicyclo[3.3.0]octanes are connected by one C–C bond to form the skeleton of 3 , which is constructed from a one‐pot nine‐component reaction. It revealed that the key factor for the preparation of these compounds is the ratio of starting materials, as well as the presence of corresponding transition metal acetates.     

A Click-Chemistry Linked 2′3′-cGAMP Analogue

2′3′-cGAMP is an uncanonical cyclic dinucleotide where one A and one G base are connected via a 3′-5′ and a unique 2′-5′ linkage. The molecule is produced by the cyclase cGAS in response to cytosolic DNA binding. cGAMP activates STING and hence one of the most powerful pathways of innate immunity. cGAMP analogues with uncharged linkages that feature better cellular penetrability are currently highly desired. Here, the synthesis of a cGAMP analogue with one amide and one triazole linkage is reported. The molecule is best prepared via a first Cu^I-catalyzed click reaction, which establishes the triazole, while the cyclization is achieved by macrolactamization.     

Synthesis and nitration of calix[4] (aza)crowns

Calix[4] (aza) crowns containing amide groups 3a-d were synthesized by the reactions of calix[4]arene (1a) or p-tert-butylcalix[4]arene (1b) with N, N'-ethylenebis(2-chloroac-etamide) (2a) or N, N'-1,2-phenylenebis(2-chloroacetamide) (2b) by one step procedure in yields of 85-90% . Calix[4]-(aza) crowns 4a-b could be obtained by the reduction of 3a-b with LiAlH4 in yields of 51 and 67% , respectively. The nitration of 3a or 3c afforded new chromogenic calix[4]arenes 5a bearing two nitrophenol moieties and 5c bearing one nitro-phenol and one quinone moiety, respectively. The ipso-nitrations of 3b and 3d were also studied. Both gave the products containing one nitrophenol and one quinone moiety. Moreover, a very interesting calix[4]arene derivative 5d containing one cyclohexadienone moiety was also separated as the main product when 3d was ipso -nitrated.     

A review on microfluidics in the detection of food pesticide residues

This paper briefly explains the food safety problems related to pesticide residues and introduces microfluidics technology as a pesticide residue detection method. Three mainstream microfluidic detection devices are detailed: one driven by liquid surface tension, one by motor siphon drive, and one by centrifugal force. The advantages and disadvantages of each are considered in an analysis of future trends in microfluidic technology for pesticide detection.     

化学修饰法表征Bacillus smithii T7产耐热菊粉酶催化活性中心的必需氨基酸残基

采用化学修饰法研究了史氏芽胞杆菌Bacillus smithiiT7产耐热菊粉酶活性中心氨基酸残基,发现该酶活性中心存在一个组氨酸残基和一个谷氨酸(或天冬氨酸)残基.修饰前后的酶动力学参数变化表明组氨酸残基参与了底物的结合和催化过程,而谷氨酸(或天冬氨酸)的羧基亲核攻击促使底物分解.邹氏作图法证明酶活性中心存在两个必需的色氨酸残基,荧光和圆二色光谱研究表明色氨酸残基在酶的催化和酶的耐热性方面起重要作用.     

Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability

Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a “natural” gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self‐assembly, that is, the independent but simultaneous formation of two coexisting self‐assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man‐made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self‐assembly.     

The use of moment theory to interpret diffusion and sieving measurements in terms of the pore size distribution in heteroporous membranes

Moment theory has been applied to model porous membranes to show that one can place reasonable bounds on the cumulative pore size distribution, the hindered diffusivity or the reflection coefficient of large solutes in a heteroporous membrane by measuring the diffusive permeability to a small solute, the hydraulic permeability and one or two additional transport characteristics. These additional measurements involve either the flux of a small solute at Pe1, the hindered diffusivity of a large solute or the reflection coefficient of a large solute at Peå1. Membrane heteroporosity is incroporated in the predicted bounds without requiring one to make any a priori assumptions about the nature of the pore size distribution. In this paper, the results from calculations performed with different model membranes containing log-normal pore size distributions are reported. A comparison of the results obtained with three different membranes shows that one can distinguish between membranes with the same average pore size but different pore size distributions by measuring either the hindered diffusion coefficient or the reflection coefficient of two different sized solutes. A comparison of the bounds on D and the bounds on σ predicted from different types of transport measurements shows that, under certain conditions, one can place tighter bounds on one transport characteristic by measuring a different one.     

An Efficient One‐Pot Four‐Segment Condensation Method for Protein Chemical Synthesis

Successive peptide ligation using a one‐pot method can improve the efficiency of protein chemical synthesis. Although one‐pot three‐segment ligation has enjoyed widespread application, a robust method for one‐pot four‐segment ligation had to date remained undeveloped. Herein we report a new one‐pot multisegment peptide ligation method that can be used to condense up to four segments with operational simplicity and high efficiency. Its practicality is demonstrated by the one‐pot four‐segment synthesis of a plant protein, crambin, and a human chemokine, hCCL21.     

A Robust Solution-Based Approach to Monodisperse Hybrid Janus Nanofibers

Monodisperse hybrid Janus nanofibers with the structure that one Au nanoparticle (AuNP) is connected to one end of a polymeric nanofiber were prepared by the self‐assembly between polymeric micelles and the tadpole‐like conjugates resulting from one‐to‐one complexation of long DNA chains with AuNPs.     

界面缩聚Ⅷ 合成聚碳酸酯的光气化——界面缩聚“一步法”基础研究

本方案的特点是,在预加有催化剂的前提下,使全量光气的有机溶液,同步地与双酚A的碱性水溶液进行光气化——界面缩聚厦应,合成聚磺酸酯。笔者等对有关的近10个影响园素,都逐个地进行了系统的实验考察。求得对其反应规律全面、系统的了解和理解。从而初步建立起光气化——界面缩聚“一步法”基础理论体系。理论和实践一致表明,正确地实施“一步法”可兼收优质．高产、低耗的综合功效,且易于实现合成工艺的连续化。     

Asymmetric Bipyridine‐Terpyridine‐Copper(II) Complexes: An Approach for New Supramolecular Architectures

On the way towards novel supramolecular assemblies and polymers, several copper(II) complexes consisting of one terpyridine as well as one bipyridine ligand were synthesized in a one‐step reaction. The compounds were characterized by UV/VIS spectroscopy and MALDI‐TOF mass spectrometry. Single crystals were obtained and their structures were determined by X‐ray analyses.     

Preparation of macrocyclic di- and tetraamides containing unsubstituted macroring nitrogen atoms,tertiary amine sidearms and/or piperazine subcyclic units

Seven new macrocyclic di- and tetramides have been prepared by the cyclization reaction of various polyamines or, in one case, a dimercaptan with a bis(α-chloroamide) or diethyl malonate. Three of the resulting macrocyclic diamides were reduced with borane to form the corresponding polyaza-crown analogs. Macrocycles prepared include two tetraaza-12-crown-4, two tetraaza-13-crown-4, two tetraaza-14-crown-4, one dithiadiaza-14-crown-4, one tetraaza-15-crown-4 with a piperazine subcyclic group, one dibenzotetraaza-24-crown-8 and one octaaza-30-crown-8 with two piperazine subcyclic groups.     

Preparation and partial characterization of a soluble site-to-site directed enzyme complex composed of alcohol dehydrogenase and lactate dehydrogenase

A soluble, bifunctional enzyme complex has been prepared by crosslinking lactate dehydrogenase and alcohol dehydrogenase with glutaraldehyde. The crosslinking was performed on a solid phase while the active sites of alcohol dehydrogenase and lactate dehydrogenase were held adjacent to one another with the aid of a bis-NAD analog. Subsequently, the enzyme complex was released from the solid phase. The soluble enzyme complex was then purified by using NAD-Sepharose as an affinity adsorbent. Based on gel filtration experiments, the complex was estimated to consist of one of each dehydrogenase. By using a third enzyme, lipoamide dehydrogenase, which competes with lactate dehydrogenase for NADH produced by alcohol dehydrogenase, the effect of site-to-site orientation was studied. It was found that about 83% of the NADH produced by alcohol dehydrogenase was oxidized by site-to-site oriented lactate dehydrogenase compared to a figure of only about 61% obtained in an identical system of separate enzymes. This indicates that given two alternative routes, the preference for the one to lactate dehydrogenase over the one to lipoamide dehydrogenase is enhanced when lactate dehydrogenase and alcohol dehydrogenase are site-to-site oriented.     

Hydrothermal Synthesis and Crystal Structure of Complex Mn2(phen)2(p-MBA)4(H2O)

A novel Mn(Ⅱ)complex Mn2(phen)2(p-MBA)4(H2O)has been hydrothermally synthesized by the reaction of P-methyl benzoic acid(p-MBA)with 1,10-phenanthroline(phen).Crystal data for this complex:monoclinic,space group C2/c,a=2.3328(3),b=1.5549(2),c=1.5557(2)nm,β=121.726(2)°,V=4.7997(11)nm3,Mr=1028.85,Dc=1.424 g/cm3,Z=4,F(000)=2128,μ(MoKa)=0.590mm-1,GOOF=1.060,R=0.0333 and wR=0.0767.In the crystal,each Mn(Ⅱ)ion is coordinated by two nitrogen atoms from one o-phenanthroline molecule.three oxygen atoms from three P-methyl benzoic acids and one oxygen atom from one water molecule,giving a six-coordinate distorted octahedral coordination geometry.Two neighboring Mn(Ⅱ)ions are bridged by two P-methyl benzoic acid groups and one water molecule,and their end positions are respectively coordinated by one 1,10-phenanthroline and one p-methyl benzoic acid molecule,giving a binuclear cage structure,of which the Mn(Ⅱ)…Mn(Ⅱ)distance is 0.3502 nm.     

Hydrothermal Synthesis and Crystal Structure of Complex Mn2（phen）2（p-MBA）4（H2O）

A novel Mn（Ⅱ） complex Mn2（phen）2（p-MBA）4（H2O） has been hydrothermally synthesized by the reaction of p-methyl benzoic acid （p-MBA） with 1,10-phenanthroline （phen）. Crystal data for this complex： monoclinic, space group C2/c, a= 2.3328（3）, b =1.5549（2）, c = 1.5557（2） nm, β = 121.726（2）°, V= 4.7997（11） nm^3, Mr = 1028.85, Dc = 1.424 g/cm^3, Z = 4, F（000） = 2128, μ（MoKa） = 0.590mm^-1, GOOF = 1.060, R = 0.0333 and wR = 0.0767. In the crystal, each Mn（Ⅱ） ion is coordinated by two nitrogen atoms from one o-phenanthroline molecule, three oxygen atoms from three p-methyl benzoic acids and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. Two neighboring Mn（Ⅱ） ions are bridged by two p-methyl benzoic acid groups and one water molecule, and their end positions are respectively coordinated by one 1,10-phenanthroline and one p-methyl benzoic acid molecule, giving a binuclear cage structure, of which the Mn（Ⅱ）…Mn（Ⅱ） distance is 0.3502 nm.     

煤基重质产物对滨州90#沥青的改性作用

对照优质道路沥青改性剂TLA,考察了六种煤基重质产物对滨州90#沥青的改性作用及作用原理。实验结果表明,六种改性剂对滨州90#沥青均表现出一定的改性作用。依据美国ASTM D5710-95以及英国BSI BS3690对TLA改性沥青的标准,六种改性沥青中,四种符合标准要求,其余两种不符合延度指标要求。FT-IR谱图分析表明,煤液化或煤油共处理重质产物的添加,没有生成新官能团,但使官能团的分布发生了变化,从而改善了基质沥青的路用性能,添加TLA,可增加C=O和S=O极性官能团,可增加沥青与石料的作用;煤焦油沥青过高的芳香结构,妨碍了其与基质沥青的混合作用。结合四组分分析结果,基于沥青胶体化学理论分析,发现不符合要求的改性沥青具有较高的饱和分含量,导致了较小的CI值(胶体指数),不利于沥青胶体结构的稳定。按线性加和法计算得到的改性沥青CI值与实测值的差距表明,改性过程包含有一定程度的化学反应。     

Syntheses,Crystal Structures,and Antibacterial Activities of Four Schiff Base Copper(II), Zinc(II), and Cadmium(II) Complexes Derived from 2‐[(2‐Dimethylaminoethylimino)methyl]phenol

Four Schiff base complexes, [Zn₂L₂(NCS)₂] ( 1 ), [Cd₂L₂(NCS)₂]_n ( 2 ), [Zn₄L₂(N₃)₂Cl₄(OH₂)(CH₃OH)] ( 3 ), and [Cu₄L₂(N₃)₂Cl₄(OH₂)(CH₃OH)] ( 4 ) (where L = 2‐[(2‐dimethylaminoethylimino)methyl]phenol), were synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X‐ray determinations. Both 1 and 2 are structurally similar polynuclear complexes. In 1 , each Zn atom has a slightly distorted square‐pyramidal coordination configuration. In the basal plane, the Zn atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The apical position is occupied by one terminal N atom of a coordinated thiocyanate anion. The Zn···Zn separation is 3.179(3) Å. While in 2 , the Cd1 atom is six‐coordinated in an octahedral coordination. In the equatorial plane, the Cd1 atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The axial positions are occupied by the terminal N and S atoms from two bridging thiocyanate anions. The coordination of Cd2 atom in 2 is similar to those of the zinc atoms in 1 . The Cd···Cd separation is 3.425(2) Å. Both 3 and 4 are novel tetra‐nuclear complexes. Each metal atom in the complexes has a slightly distorted square‐pyramidal coordination. The arrangements of the terminal metal atoms are similar, involving one O and two N atoms of one L ligand and one bridging Cl atom defining the basal plane, and one O atom of a coordinated water molecule or MeOH molecule occupying the apical position. The coordinations of the central metal atoms are also similar. The basal plane of each metal atom involves one O atom of one L ligand, one terminal Cl atom, and two terminal N atoms from two bridging azide groups. The apical position is occupied by a bridging Cl atom which also acts as a basal donor atom of the terminal metal atom. The Schiff base ligand and the four complexes showed high selectivity and antibacterial activities against most of the bacteria.     

Computational insight into the Rh-mediated activation of white phosphorus

Density functional calculations on the reaction of white phosphorus with the ligand bis(diphenylphosphino)methyl (dppm) at a rhodium center are presented. The cationic transition metal fragment can react as a nucleophilic as well as an electrophilic species, driven by a simple twisting of the four-membered rings. As a consequence of the conformational controlled philicity, the insertion reaction into white phosphorus occurs with a small energy barrier. The white phosphorus tetrahedron can be chelated by two cationic transition metal fragments into an opened bicyclobutane moiety, strongly stabilized by π-stacking interactions of the phenyl groups at the two transition metal fragments. It causes a 2:1 coordination; in the first stage of the reaction two molecules of the fragment add to one molecule of white phosphorus. The resulting dicationic complex easily undergoes dissociation into a cationic monoaddition product plus one cationic transition metal fragment. The ring expansion reaction of one ligand is explained by a j-step mechanism in one intermediary product. One ligand of the transition metal fragment dissociates and facilitates, by a cascade of low-energy processes, the rearrangement of the P(4)-moiety. Under bipyramid formation a PP-bond is broken, and the free ligand finally attaches to one phosphorus atom. Overall the reaction can be divided in low-energy processes, which pass through different unstable intermediates and more high-energy processes, requiring ligand dissociation.     

Direct conversion of macrocyclic furans into macrocyclic isothiazoles

The first calixhetarenes with more than one heteroatom in the constituent rings are prepared in one step by treatment of calix[4]furan 1a and calix[6]furan 1b with ethyl carbamate, thionyl chloride and pyridine to give 2, 3, 4 and 5, 6, 7 respectively; these products have been characterised by X-ray crystallography which reveals that in 2 all eight heteroatoms lie on one face of the macrocyle.