PREPARATION AND EVALUATION OF HPLC BONDED PHASE WITH L-PROLINE LIGAND

This paper describes a simple method for the preparation of L-proline stationary phase bonded to silica gel and characterization of the bonded phase by IR spectrometry, elemental analysis and nitrogen adsorption method at low temperature.The enantiomeric resolutions of 3-(2-pyridyl)-3-aminopropionic acid and 2,3-diaminobutanoic acid on the bonded phase were carried out.

A Modified Method for the Synthesis of Tetradentate Ligand Involving Peptide Bond

In view of the importance of picolinic acid (Pa) in preventing cell growth and arresting cell cycle, attempts were made to design, synthesize and characterize two new Pa based tetradentate ligands (DPPTR and DPPTY) with a modified procedure. The procedure reported here avoids by-products and provides better yield and purity.

Mechanochemistry of catch bonds between integrins and ligands

Integrins are a large family of adhesion molecules broadly expressed on the surface of a wide variety of cells as heterodimers.Binding of integrins to ligands provides anchorage and signals for the cell,making them prime candidates for mechanosensing molecules.To elucidate how force regulates integrin/ligand dissociation,we used molecular mechanics experiments

Synthesis, Characterization and Crystal Structure of a New Schiff Base Ligand from a Bis(Thiazoline) Template and Hydrolytic Cleavage of the Imine Bond Induced by a Co(II) Cation

The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H2L (1). Characterization of the ligand was performed by FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO3)2·6H2O and CuCl2·2H2O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.

不同V型辅助配体构筑的两个镉配位聚合物的合成、结构和荧光性质

在溶剂热条件下,合成了2个基于V型辅助配体(bipmo、bppmo)的镉配位聚合物{[Cd(bipmo)(NDC)]·1.75H_(2)O}_n (1)和{[Cd(bppmo)(NDC)(H_(2)O)]·H_(2)O}_(n) (2),其中H_(2)NDC=2,6-萘二羧酸,bipmo=双(4-(1H-咪唑-1-基)苯基)甲酮,bppmo=双(4-(吡啶-4-基)苯基)甲酮。利用单晶X射线衍射、键价和分析、红外光谱和元素分析对其结构进行了表征。研究发现,配合物1具有二重互穿的{6~3}拓扑结构。配合物2同样是3-连接的{6~3}拓扑,却存在三重穿插结构。分析表明,V型配体对最终结构的形成有很大影响。此外,对配合物1和2的发光性质也进行了详细研究。

Phytochemicals of Aloe barbadensis miller as Potential Inhibitors of Uropathogenic Escherichia coli for Urinary Tract Infection Therapy: An in Silico Approach

Urinary tract infections (UTIs) are common infections caused by normal skin or rectum bacteria that get into the urethra and infect the urinary tract. Although the infection can affect various parts of the tract, bladder infections are the most prevalent kind. Uropathogenic Escherichia Coli (UPEC) is the most common pathogen associated with UTI development. Therefore, inhibiting the UPEC protein target (PDB ID: 8BVD) appears to be a promising therapeutic strategy. Therefore, in this study, molecular docking and dynamics were conducted to examine the antibacterial activity of Aloe barbadensis miller against UPEC bacteria. The Aloe barbadensis miller natural compounds licochalcone A, palmidin B and palmidin C were downloaded from PubChem with amoxicillin, which was used as a control drug and studied against the target molecule. The potential parameters examined were the docking scores, absorption, distribution, metabolism, excretion, toxicity (ADMET), bioavailability, root mean square deviation (RMSD), root mean square fluctuation (RMSF), hydrogen bonding, radius of gyration, and potential energy of the system. Docking scores showed that all ligands demonstrated an admirable candidature as an inhibitor to 8BVD molecule, and the score hierarchy is licochalcone A (-6.4 kcal/mol), palmidin C (-6.1 kcal/mol), palmidin B (-6.0 kcal/mol), and amoxicillin (-5.9 kcal/mol). All ligands appeared to have good drug-like properties and oral bioavailability. Molecular dynamic studies showed that all ligands exhibited an excellent nominee as inhibitors in their vicinity at 20 ns. However, there is a relatively high fluctuation of palmidin B compared with other compounds, which seems to be more stable. This work suggests that the selected phytoconstituents could be used as inhibitors of the 8BVD protein in the fight against UTIs. However, further investigation on the clinical and experimental validation of UTI treatment’s specific mechanisms and effects is still welcomed.

Bonding Characteristics and Magnetic Coupling Interactions in One-dimensional α′-NaV_2O_5

The spin-polarized generalized gradient approximation（GGA）＋U approach was employed to study the bonding characteristics and magnetic coupling interactions in room-temperature phase α＇-NaV2O5. The calculated resuits indicate that the Vdry orbital is split off from other 3d orbitals in the VO5 pyramidal ligand field. The Vdry orbitals are hybridized strongly with the Opx/py orbitals, forming a V--O--V π bond in the ab plane. The ligand field effect together with the intra-atomic exchange splitting results in the insulating behavior. With the aid of Noodleman＇s bro- ken symmetry methods, the magnetic exchange constant was derived from mapping the relative energies onto the Heisenberg model. The antiferromagnetic（AFM） exchange energy, d, along the chain was calculated to be -593 K in good agreement with the experimental data.

Synthesis and Crystal Structure of a New Mixed-ligand Cluster[Mo_3O_4(C_2O_4)_2bipy(H_2O)_3]·EtOH·2H_2O(bipy = 2,2'-Bipyridine)

The novel mixed-ligand neutral compound [Mo3O4（C2O4）2bipy-（H2O）3]·EtOH·2H2O（bipy = 2,2′-bipyridine） has been prepared by the reaction of oxalic acid elution of Mo（IV） and bipy, and characterized by single-crystal X-ray diffraction analysis and IR. The crystal is of triclinic, space groups P1^- with a = 9.5520（2）, b = 10.3730（1）, c = 13.5722（2）A, a = 74.940（12）,β = 80.772（14）,γ= 69.898（11）°, V = 1215.73（11）A^3, Z = 2, C16H24Mo3N2O18, Mr = 820.19, Dc = 2.241 g/cm^3,μ = 1.616 mm^-1, F（000） = 808, T = 293（2） K, the final R = 0.0424 and wR = 0.0939 for 4119 observed reflections with I 〉 2σ（I）. The trinuclear unit is coordinated by mixed ligands of oxalate and bipy. The intermolecular hydrogen bonding interactions among adjacent [Mo3O4（C2O4）2·bipy（H2O）3] extend the compound into a three-dimensional supramolecular framework. The uncoordinated water molecules and ethal molecules act as space-fillers and consolidate the whole architecture through hydrogen bonding interactions.

Organic Carboxylate Ligand Tuned Topological Variations in Three Zn(Ⅱ)Coordination Polymers:Syntheses,Crystal Structures and Photoluminescent Properties

Three new Zn（Ⅱ） coordination polymers, namely [Zn2（suc）2（bib）2]n·nH2 O（1）, [Zn（glu）（bib）]n·4 nH2 O（2）, and [Zn（adp）（bib）]n（3）（bib = 1,4-bis（N-imidazolyl）butane, H2 suc = succinic acid, H2 glu = glutaric acid, H2 adp = adipic acid） have been hydrothermally synthesized and structurally characterized. Compound 1 features a 3D framework with 4-connected hxg-d topological network, compound 2 is comprised of 2D 44-sql-type sheets, and the adjacent 2D sheets are further packed into a 3D supramolecular architecture via intermolecular hydrogenbonding interactions, and compound 3 is a 3D framework with 4-fold interpenetrating dia topology. The structural comparison of these three compounds demonstrates that the topological variations can be well controlled by employing aliphatic dicarboxylate ligands with different spacer lengths. Moreover, the thermal stabilities and photoluminescent properties of them were also studied in detail.

Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

The title complex, [ [ Cd（Him） （OH-BDC） （H2O）2 ]· 3H2O]n （ 1 ） （Him is imidazole, OH-H2BDC is 5-hydroxyisophthalic acid）, was synthesized by liquid/liquid diffusion method at room temperature. The complex crystallizes in orthorhombic, space group P212121, with a = 0.671 6 （7）, b = 1.380 6 （2）, c = 1.7421（2） nm, V = 1.615 2（3） nm3, C11H18CdN2O10, Mr = 450.67, Dc = 1.853 g/cm3, μ = 1.407 mm^-1, F（000） = 904, Z = 4, the final R1 = 0.020 9 and wR2 = 0.045 3 for 3 211 observed reflections （Ⅰ 〉 2σ （Ⅰ））. In the structure of 1, the OH-BDC ligands exhibiting bis-bidentate coordination mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain. It is notable that a series of complicated hydrogen bonds （e. g., N-H… O, O-H… O） exist in the structure, which link neighboring helices into a three-dimensional supramolecular architeeture. An observed intense blue luminescence with an emission band peaking at 390 nm for 1 may be resulted from ligand-to-metal charge transfer （LMCT）.

Synthesis,Crystal Structure and Properties of a Novel Decavanadate Complex with One-dimensional Chain Involving Sodium and 'Bis-tris' Ligand

By using a flexible multidentate ligand,bis（2-hydroxyethyl）iminotris（hydroxyhydroxylmethy）methane（＇bis-tris＇：H5L）,the title complex {[Na（H6L）2]2}n·nV10O28（1） has been successfully synthesized under self-assembly condition and characterized by IR spectroscopy,elemental analysis,PXRD and single-crystal X-ray diffraction.The crystal structure belongs to an orthorhombic system,space group Cmca with a = 23.752（2）,b = 13.5360（8）,c = 18.5377（11） ,V = 5960.1（7）,Z = 8,Dc = 2.055 g/cm3,F（000） = 3744,μ = 1.630 mm-1,the final R = 0.0283 and wR = 0.0759 for 3353 observed reflections with I 〉 2σ（I）.This complex consists of decavanadate [V10O28]6-motifs as counter anions intercalated with one-dimensiond chains of the composition [Na（H6L）2]n3n＋.And significant intermolecular O-H…O hydrogen-bonding interactions lead to a three-dimensional supramolecular framework.

Synthesis and Characterization of a Metal-Organic Framework Bridged by Long Flexible Ligand

3D supramolecular network with considerable volume pores was created via hydrogen bond & C-H--π. By tightening of The metal-organic frameworks (MOF) namely [Ni(μ-pmb)2(H2O)2]n (pmb = 3,5-bis(4-pyridylmethylenoxyl) benzoate, that have been synthesized by hydrothermal method. Complex 1 crystallizes in triclinic P-1 space group and consists of 1D semi zigzag chain.

Molecular Structure of Co₂(<i>μ</i>-Alkyne) Complex Containing Ph₂PC₅F₆PPh₂Ligand

Oxidative-decarbonylation of Co2(CO) 6(μ-PhC≡CH) with Me3NO in the presence of an electron deficient ligand, Ph2PC5F6PPh2 (F6FOS), produces Co2 (CO) 4 (μ-PhC≡CH)(F6FOS), (1). The metrical values of 1 have been compared to those of the closely related cobalt carbonyl alkyne compound A containing (Z)-Ph2PCH=CHPPh2 (Z-dppe) ligand. Strikingly anomalous is an alkyne C≡C bond (1.34(1) ? in 1, which is somewhat elongated compared to A (1.31(1) ?). When taking a strong electron-withdrawing power of fluoride atom into account, F6FOS ligand appeared to reduce the π-back-donation ability of cobalt atom, making this bond shortened in comparison to the same bond in A. Bond lengthening in the alkyne C≡C bond in 1 is attributed to the enhanced electron donor ability of F6FOS compared to Z-dppe and can be understood by examining resonance structures of F6FOS ligand.

多巴仿生润滑剂在水基钻井液中的应用及机理研究

利用多巴强大的水下黏附性能,合成了一种适用于水基钻井液的多巴仿生润滑剂L_(2,3)。这种新型润滑剂解决了长期以来酯类润滑剂在水中因黏附性较差无法在钻具表面形成有效润滑膜而导致的润滑性能变差的问题。此外,合成了酚羟基位置不同的润滑剂L_(2,5),并通过FT-IR光谱和1H NMR对其进行表征。通过极压润滑仪、泥饼黏附系数测试仪、四球摩擦仪和扫描电子显微镜(SEM)评估润滑性能和耐磨性。在钠基膨润土基浆(Na-BT)中,L_(2,3)具有最好的润滑性能,1%加量下摩擦系数(COF)低至0.07,COF降低率达到87.7%,磨痕直径(WSD)为0.587 mm,在210℃以内,均能保持良好的润滑性能且不起泡。相比之下,L_(2,5)在清水中润滑性较好,摩擦系数为0.1,但在Na-BT中无法抵御黏土颗粒的剪切,润滑膜脱落,摩擦系数为0.57,接近未添加润滑剂的空白Na-BT。通过X射线光电子能谱(XPS)分析了表面润滑膜的成分和厚度,发现酚羟基结构提高了润滑剂在金属表面的黏附能力,进而提高了其润滑和抗磨性能,具体还与酚羟基类型有关。含有邻苯二酚结构的L_(2,3)通过双齿金属配位键在金属表面形成了一层致密的厚度超过80 nm的有机膜;而含有对位羟基结构的L_(2,5)只能在表面形成一层厚度低于20 nm的润滑膜。由于L_(2,3)在金属表面形成的双齿金属配位键更加稳定,所以其润滑和抗磨性能远高于L_(2,5)。

Two Cobalt(II) Complexes Derived from the Hydrolysis Product of Di-Schiff Base Ligand N,N'-Bis-(1-benzimidazo-2-yl-ethylidene)-ethane-1,2-diamine:Preparation,Characterization and Crystal Structure of the 6-Coordinate Species [CoL_2]X·H_2O (X = ClO_4^-, N

The reactions of Co（C1O4）2·6H2O and Co（NO3）2.6H2O with the di-Schiff base ligand N,N＇-bis-（1-benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine （LA） in ethanol have been investigated. The reactions of LA with excess amount of cobalt salts yield the six-coordinate complexes [CoL2]（ClO4）E·H2O 1 and [CoL2]（NO3）E·H2O 2 as isolatable products （L= N-（1- benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine）, where L is a tri-dentate mono-Schiff base ligand, resulting from the hydrolysis of the precursor di-Schiff base LA. Both complexes were characterized by X-ray crystallography. Crystal data for complex 1： monoclinic, space group P21/c, a = 11.9214（10）, b = 23.5828（17）, c = 14.0387（12）A, β = 135.219（4）°, C22H30Cl2CoN8O9, Mr = 680.37, V = 2780.1（4） A^3 ,Z = 4, Dc = 1.625 g/cm^3,μ（MoKa） = 0.876 mm^-1, F（000） = 1404, the final R = 0.0725 and wR = 0.1530 for 5726 observed reflections （I 〉 2σ（I））. Crystal data for complex 2： monoclinic, space group P21/c, a = 18.2162（16）, b = 10.0610（6）, c = 18.593（2）A, β = 130.099（3）°, C22H30CoN10O7, Mr = 605.49, V = 2606.5（4） A3 Z = 4, Dc = 1.543 g/cm^3,μ（MoKa） = 0.722 mm^-1, F（000） = 1260, the final R = 0.0619 and wR = 0.1429 for 5194 observed reflections （I 〉 2σ（I））. X-ray diffraction analysis reveals that each cobalt atom in the two complexes is chelated by six nitrogen atoms from two tridentate iigands L, exhibiting a slightly distorted octahedral coordination sphere. In both complexes, the strong hydrogen-bonding interactions between the lattice waters and N-H groups of the ligands result in 1D chains which are further connected by ClO4^- （or NO3^-） groups to form a 3D framework. In complex 2, the strong π-π interactions increase the stability of the structure.

三个二羧酸配体配位聚合物的合成、结构表征和荧光性质

以羧酸配体2,2′-(1,4-亚苯基双(亚甲基))双(硫二基)二苯甲酸(H_(2)L^(1))和2,2′-(2,3,5,6-四甲基-1,4-亚苯基)双(亚甲基)双(硫二基)二苯甲酸(H_(2)L^(2))分别与金属盐反应,通过溶剂热方法合成了3个配位聚合物:{[Ni(L^(1))(H_(2)O)_(4)]·2H_(2)O}_(n)(1)、[Zn(L^(1))(DMA)_(2)]_(n)(2)和[Co(L^(2))(DMF)_(2)]_(n)(3),其中DMA=N,N-二甲基乙酰胺,DMF=N,N-二甲基甲酰胺。对配合物1~3进行了单晶X射线衍射、元素分析、红外光谱、热重分析、粉末X射线衍射和固体紫外可见光谱测试和表征。单晶X射线衍射表明:3个配合物均为一维锯齿形链状结构,并通过氢键作用形成三维骨架,且配体均表现为反式构象。此外,对配合物2固态荧光性质进行了研究。

铀酰大环配体化合物的理论研究进展

锕酰离子与配体的相互作用本质在锕系元素组分离的应用中具有重要意义,因此本课题组近几年一直致力于这方面的研究.本文对铀酰与大环配体形成的配合物的配位结构、稳定性和成键性质进行了综述和规律性总结.首先,研究发现锕酰大环配合物的配位结构取决于大环配体的腔体大小;其次,侧配位时,铀酰倾向于形成1∶2稳定结构,而嵌入式结构时,铀酰倾向于形成1∶1稳定结构;再次,通过对一系列配体的研究,发现环尺寸为18的配体,在与铀酰结合时表现了优异的配位能力,其中[CHP]^(4-)具有最强的结合能力;最后,这种稳定主要是由于U-N共价性大于U-O及U-S.这些结构规律和成键特征,为实验上筛选合理且高效分离锕系元素的配体提供了重要理论指导.

半刚性吡啶鎓类两性离子型Zn(Ⅱ)配合物的合成及结构研究

选择一种半刚性吡啶鎓两性离子型羧酸配体1,1’-(1,3-亚苯基双(亚甲基))双(4-羧基吡啶-1-鎓)氯化物(H2LCl2),在水热条件下与Zn(Ⅱ)离子成功构筑出一例两性离子型配合物,即[ZnL2(ClO4)2(H2O)4]·3H2O。X-单晶衍射结果表明,此配合物属于单斜晶系P21/n空间群。在配合物中,Zn(Ⅱ)中心以六配位的模式形成一个稍微扭曲的八面体[ZnO6]单元结构。除此之外,有机配体中的—CH2—基团旋转使得配体展现出类似于“凹”字型的结构,这使得配体间的π-π堆积和氢键作用将配合物从零维向三维延展,形成一个三维超分子结构。

Suzuki偶联反应的最新研究进展

Suzuki偶联反应是合成联芳烃化合物的最有效方法之一 ,近几年来一直是催化化学和有机化学的研究热点 .综述了最近几年来Suzuki偶联反应及其在有机合成中的应用研究进展 .

二氧化钛表面键合配位体固相萃取填料的制备及其吸附性能研究

有机配位体/无机纳米复合材料作为固相萃取填料用于重金属离子分离富集是当前分析化学研究的热点课题。本文将含有N、S配位原子的氨基硫脲通过缩合反应接枝于纳米二氧化钛表面,制备了一种新型纳米Ti O2/TSC复合固相萃取填料。通过红外光谱、X射线衍射、X射线光电子能谱和扫描电镜表征,此填料与共混法制备的聚合物包覆纳米二氧化钛复合填料相比,二氧化钛粒子(尺寸200~300 nm)分布更均匀,结构更稳定。用该填料制备的固相萃取小柱静态吸附Sb3+、Cd2+和Ba2+在30℃时饱和吸附量分别为13.9mg/g、12.9 mg/g和11.2 mg/g,在优化的实验条件下三种金属离子的吸附回收率分别达到97.94%、95.65%和94.04%,实验数据重现性高(RSD<5.5%),吸附性能优于聚苯乙烯-甲基丙烯醛-氨基硫脲包覆纳米二氧化钛和纳米二氧化钛两种填料。本填料结合ICP-MS测定水样中以上三种离子的检出限分别为0.061μg/L、0.013μg/L和0.075μg/L。