Novel Mannich Bases of Benzimidazole Derivatives: An Antibacterial Study of Environmental Bacterial Strains

A previous study was conducted on the synthesis and antibacterial evaluation of Mannich bases of 2-(thioalkyl)-1H-methylbenzimidazole derivatives. The results of this study showed that certain 2-(thioalkyl)-1H-methylbenzimidazole and 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl)benzimidazole derivatives possess antibacterial activities against clinical strains, such as Escherichia coli, Klebsiella pneumonia (Gram-negative bacteria), Staphylococcus aureus and Pseudomonas aeruginosa (Gram-positive bacteria). Following these favorable results, we extended the antibacterial evaluation of this series of molecules to environmental strains. The aim of this study was to assess the impact of the methyl-piperidine group fixed at position-1 of this new series of benzimidazoles on the antibacterial activity of environmental strains. In addition, we first evaluated the antibacterial activity of four 2-(thioalkyl)methylbenzimidazole derivatives and then that of five 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl) benzimidazole derivatives. This study allowed us to show that compounds 1d and 1e could inhibit bacterial growth in vitro of the Enterobacteria P1 strain with inhibition diameters of 17.3 ± 0.6 mm and 10 ± 0.0 mm, respectively. However, addition of methyl-piperidinyl in this series showed that five (5) of 2-(thioalkyl)-methyl-1-(piperidin-1-ylmethyl) benzimidazole derivatives had an inhibitory effect on the in vitro growth of bacterial strains used except on Enterobacteria P2 with inhibition diameters between 10.0 ± 0.8 mm and 27.9 ± 1.4 mm. The introduction of the methyl-piperidinyl group at the 1-position of 2-(thioalkyl)-1H-methylbenzimidazole derivatives greatly improved the antibacterial activity against environmental bacteria such as Escherichia coli A1, A2, A3, and A4 and two Enterobacteria P1.

Carbon-based derivatives from metal-organic frameworks as cathode hosts for Li–S batteries

Lithium-sulfur batteries(Li–S batteries) are promising candidates for the next generation high-energy rechargeable Li batteries due to their high theoretical specific capacity(1672 m Ahg-1) and energy density(2500 Wh kg-1). The commercialization of Li–S batteries is impeded by several key challenges at cathode side, e.g. the insulating nature of sulfur and discharged products(Li2S 2 and Li2S), the solubility of long-chain polysulfides and volume variation of sulfur cathode upon cycling. Recently, the carbonbased derivatives from metal-organic frameworks(MOFs) has emerged talent in their utilization as cathode hosts for Li–S batteries. They are not only highly conductive and porous to enable the acceleration of Li +/e-transfer and accommodation of volumetric expansion of sulfur cathode during cycling, but also enriched by controllable chemical active sites to enable the adsorption of polysulfides and promotion of their conversion reaction kinetics. In this review, based on the types of MOFs(e.g. ZIF-8, ZIF-67, Prussian blue, Al-MOF, MOF-5, Cu-MOF, Ni-MOF), the synthetic methods, formation process and morphology, structural superiority of MOFs-derived carbon frameworks along with their electrochemical performance as cathode host in Li–S batteries are summarized and discussed.

A New Schiff Base Derivatives Designed to Bind Metal Ion (Cu, Co): Thermodynamics and Biological Activity Studies

Schiff base synthesis is usually acid catalyzed and it usually requires refluxing the mixture of aldehydes and amine in ethanolic solution. Synthesis and characterization of Schiff base ligands derived from substituted amine and salicylaldehyde and their complexes (Cu2+, Co2+) are reported. The ligands and ligand-complexes were characterized by melting point, FTIR, CHN-elemental analysis and UV-Visible analysis. The UV-Visible and elemental analysis of complexes established (1:2) mole ratio (M:L). The stability constant and thermodynamic parameters (K, ΔG, ΔH, ΔS) were determined at different temperature (30 - 40)°C which established that the metal-complexes were very stable. The review describes the promising biological activities of Schiff base and their metal complexes.

STUDIES ON THE PROPERTIES OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS.II ^(199)Hg NMR SPECTRA OF MERCURATED DERIVATIVES OF SUBSTITUTED BENZYLIDENEANILINES

^(199)Hg NHR spectra of 18 Schiff base type arylmercury compounds have been studied.It was further confirmed that in the molecule of XC_6H_4CH=NC_6H_3-2-HgC1-4-CH_3 there exists an intramolecular N→Hg coordination via a four-membered ring.For the series of XC_6H_4CH=NC_6H_3-2-HgCl-4-CH_3(X is a para-or mera-substituent),there is a good linear correlation between δ^(199)Hg and Hammett's o constants.The influence of substituents of C-pheny1 ring on the δ ^(199)Hg can be explained in terms of the intramolecular N→Hg coordination.

Synthesis and spectral studies of macrocyclic Pb(Ⅱ),Zn(Ⅱ),Cd(Ⅱ)and La(Ⅲ) complexes derived from 1,4-bis(3-aminopropoxy)butane with metal nitrate and salicylaldehyde derivatives

Eight new macrocyclic complexes were synthesized by template reaction of 1,4-bis（3-aminopropoxy）butane with metal nitrate and 1,3-bis（2-formylphenyl）propane or 1,4-bis（2-formylphenyl）butane and their structures were proposed on the basis of elemental analysis, FTIR, UV-vis, molar conductivity measurements, ^1H NMR and mass spectra. The metals to ligand molar ratios of the complexes were found to be 1： 1. The complexes are 1：2 electrolytes for Pb（II）, Zn（II） and Cd（II） complexes and 1：3 electrolytes for La（III） as shown by their molar conductivities （Am） in DMSO at 10^-3 mol L^-1. Due to the existence of free ions in these complexes, such complexes are electrically conductive. The configurations of La（III） and Pb（II） were proposed to probably octahedral and Zn（II） and Cd（II） complexes were proposed to probably tetrahedral.

Preparation and Characterization of Multiester Derivative from Plant Oil as Base Stock for Biolubricants

As an alternative to petroleum-based lubricants, which are harmful to the environment in excessive amounts, a biodegradable multiester derivative(OFANE) was obtained from plant oil through a chemical modification process with four steps as follows: hydrolysis, esterification, epoxidation, and ring-opening reaction. The physical and chemical properties of OFANE, such as viscosity, acid value, pour point, evaporation loss, and oxidation induction time were measured. Results showed that OFANE had good low-temperature fluidity, thermal-oxidative stability, and tribological properties. The tribological properties of OFANE with dimeric acid additive were evaluated. The final biodegradation experiment indicated that OFANE had excellent biodegradability. The prepared OFANE showed great potential as substitute for petroleum-based lubricating base oils.

Synthesis, Characterization and Crystal Structure of Cobalt(II) Complex of a Schiff Base Derived from Isoniazid and Pyridine-4-Carboxaldehyde

A new hydrogen bonded Cobalt(II) Schiff base complex,?N’-(pyridine-4-carboxaldehyde) isonicotinoylhydrazone Cobalt(II), has been synthesized from isoniazid and pyridine-4-carboxaldehyde and characterized by IR spectroscopy, 1H-NMR, elemental analysis, TGA and single crystal X-ray structure determination. X-ray crystal structure analysis shows an octahedral complex with a metal centre coordinated to two ligand molecules through the pyridine nitrogen atoms and four water molecules and containing two nitrate groups as counter ions. The complex crystallizes in the monoclinic crystal system and P2(1)/n space group. The unit cell dimensions are: a = 7.2108(4) Å, b = 16.6020(9) Å, c = 13.0389(6) Å,α = 90°, β = 103.972(4)°, γ = 90°. The molecule is symmetrical about the cobalt centre as observed from the 1H-NMR and 13C-NMR and confirmed by the single crystal X-ray structure of the complex. Thermogravimetric analysis shows two steps decomposition of the complex to leave a metal oxide residue. The title compound is expected to be biologically active as one of the precursors (isoniazid) is a therapeutic agent with well-established clinical applications.

Synthesis and Crystal Structure of a New 2D O-bridged Copper(Ⅱ) Coordination Polymer Constructed from Sulfonate-derived Schiff Base

A new chain-like coordination polymer, namely, [CuL]n （1, Na2L = 2-[（2-hydroxy- benzylidene）-amino]-benzenesulfonic acid sodium salt）, has been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis. Complex 1 crystallizes in monoclinic system, space group P21/c with a = 9.2296（16）, b = 10.4754（18）, c = 12.200（2） A, β = 102.392（2）°, V = 1152.0（3）A3, CI3H9CuNOaN, Mr = 338.83, Dc = 1.953 g/cm3, Z = 4, F（000） = 684, p = 2.089 mm-1, the final R = 0.0376 and wR = 0.0956. X-ray diffraction analyses indicate that 1 displays a square-pyramidal metal center with NO4 donor sets. The sulfonate-derived Schiff base serves as a common N,O,O＇-tridentate and a unique O-bridged ligand connecting the metals. Dinuclear copper complexes serve as secondary building blocks （SBUs） to construct an unusual 2D coordination network. In the crystal, the components form a stable 3D supramolecular architecture by C-H...O interactions and to-stacking

NEW SOLID BASE DERIVED FROM AIPO4-5 SUPPORTED KF

Dispersion of KF on AlPO4-5 molecular sieve created basic sites and caused 1654 cm- band of bidentate carbonate in CO2 adsorption.After pre-treated above 823K. 5%KF/AlPO4-5exhibited basic catalytic activity in the isomerization of butenes at 273K. and the activity increasedwith the pre-treatment temperature up to 923K.

COMPLEXES OF RARE EARTH NITRATE WITH SCHIFF BASE DERIVED FROM VANILLIN AND P-TOLUIDINE

In this paper,complexes of rare earth nitrate with Schiff base derived from vanillin(3-methoxy-4-hydroxy-benzaldehyde)and p-toluidine[LnL_2(NO_3)_2]NO_3(Ln=La-Eu except Pm,L=Schiff base ligand) have been prepared and characterized.

Derivative-Based Midpoint Quadrature Rule

A new family of numerical integration formula is presented, which uses the function evaluation at the midpoint of the interval and odd derivatives at the endpoints. Because the weights for the odd derivatives sum to zero, the derivative calculations cancel out for the interior points in the composite form, so that these derivatives must only be calculated at the endpoints of the overall interval of integration. When using N subintervals, the basic rule which uses the midpoint function evaluation and the first derivative at the endpoints achieves fourth order accuracy for the cost of N/2 function evaluations and 2 derivative evaluations, whereas the three point open Newton-Cotes method uses 3N/4 function evaluations to achieve the same order of accuracy. These derivative-based midpoint quadrature methods are shown to be more computationally efficient than both the open and closed Newton-Cotes quadrature rules of the same order. This family of derivative-based midpoint quadrature rules are derived using the concept of precision, along with the error term. A theorem concerning the order of accuracy of quadrature rule using the concept of precision is provided to justify its use to determine the leading order error term.

能群独立的中子输运非结构网格自适应加密

为兼顾中子输运的模拟精度和计算效率,对网格进行自适应加密和区域分解并行是有效技术途径。通常各能群的中子通量密度分布有较大差异,采用统一的网格不能最佳匹配各群通量密度的空间变化,只能全局加密网格或损失精度。本文通过对各能群中子通量密度分别进行后验误差估计,开展能群独立的局部网格加密,获得与各能群的中子通量密度分别匹配的多组非结构网格,即基于共同父网格(粗网格)的多组独立子网格(细网格),进而开发了在这种层次化父-子网格上的多群中子输运模拟耦合算法,通过连续的多轮次自适应加密,实现了不受初始网格分辨率影响的高精度、高效率求解。基于该网格方法建立了间断有限元输运程序ENTER-Ⅱ,并借助开源算法库DEAL.Ⅱ实现了区域分解并行。初步验证表明,计算结果符合良好,时间效率有明显提升。

5-取代-4-氨基-3-巯基-1,2,4-三唑衍生物的应用进展

5-取代-4-氨基-3-巯基-1,2,4-三唑是一类重要的五元杂环化合物,由于分子中含有巯基和伯胺基两个活性基团,既可以单个基团参与反应生成N-或S-取代产物,又可以同时发生反应生成稠杂环化合物。由其衍生而来的化合物具有广泛的生物活性,在抗菌、抗肿瘤、抗结核、抗炎镇痛、酶抑制剂、荧光探针等方面都表现出优异的性能。综述了近年来5-取代-4-氨基-3-巯基-1,2,4-三唑衍生物在医学、农业及材料领域的应用,为今后进一步研究、开发此类化合物提供参考。

芹菜籽中芹菜素曼尼希碱衍生物抗高尿酸血症活性研究

本文旨在探究芹菜籽中降尿酸活性成分芹菜素曼尼希碱衍生物对高尿酸血症小鼠模型的降尿酸作用及其机制。通过分子对接分析,氧嗪酸钾-酵母膏诱导高尿酸血症小鼠体内试验,探索芹菜素Mannich碱衍生物8-(4-乙基哌嗪-1-甲基)-5,7-二羟基-2-(4-苯酚)-4H-1-苯并吡喃-4-酮(APN083)的抗高尿酸血症作用。结果表明,灌胃给予高尿酸血症小鼠高、中浓度(15 mg/kg、7.5 mg/kg)APN083能明显降低血清尿酸水平(P <0.05),能显著降低血清CRE水平,具有显著的降尿酸作用,能在一定程度上抑制黄嘌呤氧化酶(XO)活性,并且促进尿酸的排泄;通过分子对接分析,该化合物通过结合到XO的活性空腔,并与周围氨基酸相互作用,从而阻碍底物分子进入活性中心,降低酶的催化活性。芹菜素曼尼希碱衍生物APN083具有较好的降尿酸作用,能从一定程度上抑制XO活性。

木质素及其衍生物在木材胶黏剂中应用研究进展

以天然可再生资源替代传统化石资源开发绿色环保、性能优异的木材胶黏剂是人造板行业研究的热点。木质素来源广泛、价格低廉,且分子结构中含有羟基、甲氧基、羧基等活性基团,易于功能化修饰,是合成木材胶黏剂的理想原料。本文重点综述了木质素及其衍生物在酚醛树脂、脲醛树脂、环氧树脂、聚氨酯等合成树脂木材胶黏剂中的应用与研究现状,介绍了化学改性、降解、溶剂分级纯化等预处理方式对木质素化学反应活性及合成树脂胶黏剂力学性能的影响,探讨了木质素基木材胶黏剂目前发展面临的困难和挑战,并展望了未来应用及研究方向,以期为木质素资源的高效、高值化综合利用及高性能生物基木材胶黏剂的开发提供理论与技术参考。

生物质炭材料活化过硫酸盐降解有机污染物的研究进展

作为经济、易得的含碳材料,生物质炭已应用于高级氧化领域。以硫酸根自由基为基础的高级氧化工艺是降解有机污染物的有效方法之一。本文综述了过硫酸盐的特点及其氧化降解有机污染物的反应原理,重点分析了生物质炭材料的非金属改性(氮掺杂、硼掺杂和硫掺杂)、金属改性、表面修饰等改性方式对其活化过硫酸盐降解有机污染物的影响,讨论了生物质炭基催化剂对典型有机污染物的降解效果与机理,并展望了生物质炭基材料在活化过硫酸盐降解有机污染物领域的技术挑战和发展前景。

基于生物基衍生有机溶剂的木质纤维素预处理研究进展

木质纤维素类生物质是地球上最丰富的可再生资源,但纤维素、半纤维素、木质素三组分之间复杂的键合结构限制了其有效的转化利用。有机溶剂预处理是消除这种顽抗性的有效方法,其能有效拆解三组分、提高纤维素酶水解性能,并回收高纯木质素组分。随着对溶剂绿色和可持续性的要求,预处理有机溶剂正逐渐向生物基衍生溶剂方向发展,近期已有多种新型的生物基衍生溶剂预处理的报道。本文系统综述了基于Hansen溶度参数理论和CHEM21绿色溶剂指南的有机溶剂预处理体系设计,分别归类为均相体系、两相体系和多元相转化体系,归纳了生物基衍生预处理有机溶剂应用的研究进展,在此基础上探论了生物基衍生溶剂预处理面临的挑战和应用前景,以期为木质纤维素类生物质的有机溶剂预处理体系的设计和选择提供参考。

γ-Mo_(2)N/C催化剂的合成及其甲酸脱氢性能研究

甲酸(FA)因其H含量较高(4.4%)、易产H_(2)、可经小平台化合物合成等优势受到广泛关注,而γ-Mo_(2)N/C对FA沿H_(2)和CO_(2)路径分解具有非常高的选择性,产生CO极少,显示出较高的应用价值。基于此,本研究采用对苯二胺和钼酸铵水溶液经前驱体制备γ-Mo_(2)N/C催化剂,并对其FA分解性能进行了原位评价,采用热重分析(TG)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、透射电镜(TEM)等表征手段对催化剂的结构和表面官能团进行了分析,利用DFT对FA在γ-Mo_(2)N (200)晶面的吸附构型进行了计算,在此基础上,对催化剂性能及FA在其表面的分解机理进行了研究。结果表明,γ-Mo_(2)N/C在较低温度下即可表现出极高的催化活性,提高γ-Mo_(2)N在C载体上的分散性能有效改善FA转化率。对苯二胺与钼酸铵的物质的量比为4∶1时,催化性能最佳,在160℃、100 h的FA分解实验中,催化剂性能稳定、H_(2)选择性高(N_(2)40 mL/min, CO<5.0×10^(-5))。而DFT计算表明,FA中O-H键的H原子与γ-Mo_(2)N/C (200)晶面上N原子结合的可能性更大,而C=O键的O原子更有可能与γ-Mo_(2)N/C (200)晶面上Mo原子结合。上述结果有助于明确FA在γ-Mo_(2)N/C作用下的分解机理,也显示出非贵金属催化剂γ-Mo_(2)N/C在FA分解制H_(2)方面潜在的应用前景。

基于组分设计的MOFs衍生碳基吸波材料的研究进展

金属有机骨架(MOFs)具有孔隙率高、比表面积大等特点,其衍生物重量轻、带宽宽、损耗能力强,具有有序规整以及易设计性的组分结构而被广泛用于电磁波吸收研究。总结了单金属、双金属及金属氧化物MOFs碳基吸波材料作为微波吸收材料的性能、优势及其在电磁波吸收方面的应用等,分析了不同组分和组分设计对电磁波吸收性能的影响。尽管还面临许多的挑战,但MOFs衍生物作为电磁波吸收材料显示出广阔的发展潜力。