Schiff碱金属配合物在细菌代谢过程中的表征

采用微量热法测定了产气杆菌在四种Schiff碱金属配合物作用下的代谢热谱, 以其对数生长期的生长速率常数k表征了Schiff碱金属配合物对其细菌生长的抑制。不同的配合物其抑制情况不同。Co(II)-NG(NG : D-氨基葡萄糖-β-萘酚醛Schiff碱)对产气杆菌的抑制作用最大, 随着浓度c的增加抑制作用增大, 在350μg.mL^-^1时可完全抑制其生长, 但k-c并不呈线性关系; Fe(II)-NG对产气杆菌的抑制较小, 且在50-300μg.mL^-^1浓度范围内k与浓度无关, 在350μg.mL^-^1时才略表现有一定的抑制作用; Cu(II)-NG和Zn(II)-NG对产气杆菌的抑制作用也较小, 且k随着浓度的变化不规则, 同时发现热谱上最大热输出功率Pmax与生长速率常数存在正比关系, 进而推出在实验条件相同的情况下可用Pmax代替k。     

几种含吡啶双酰胺基双Schiff碱对大肠杆菌的抑菌活性研究

使用LKB 2277热活性监测器测定了大肠杆菌在几种含吡啶双酰胺基双Schiff碱作用下的生热曲线,得到了不同Schiff碱在不同浓度下大肠杆菌生长代谢的生热速率常数k、传代时间、半抑制量浓度。结果发现,含有2,4-二羟基苯甲醛双Schiff碱(Ⅱa和Ⅱg)对大肠杆菌生长代谢的抑制活性要明显大于含其他Schiff碱,而杂环Schiff碱对大肠杆菌抑菌活性顺序为吡啶噻吩呋喃。     

Schiff碱药物对产气杆菌代谢抑制的热力学研究

用微量热法测定产气杆菌在不同温度条件下受到Schiff碱药物抑制的热谱曲线, 根据其指数生长期的热谱信息, 确定它在不同温度条件下的生长速率常数和反应活化能, 找出了该细菌的最佳生长温度。同时借用化学反应中的过渡态理论, 得到一系列热力学参数, 对细菌在受到抑制时的生长代谢进行了热力学分析。     

Schiff碱药物与细菌作用的半抑制量比较研究

用微量热法测定了金黄色葡萄球菌和产气杆菌分别与十一种Ｓｃｈｉｆｆ碱药物作用的热谱曲线根据热谱曲线计算了细菌生长的速率常数Ｋ，建立了Ｋ～Ｃ关系式，进行在获得的Ｓｃｈｉｆｆ碱药物对细菌作用的半抑制量Ｃ１／２的基础上，通过对半抑制量大小的比较，分别对配体相同金属离不同，金属离子相同配体不同的Ｓｃｈｉｆｆ碱药物与细菌的作用以及对同一药物与不同细菌作用的情况做了较深入的讨论，发现，同一药物对不同的菌种其药效     

微量热法研究Schiff碱药物的抗菌作用

微量热法研究Ｓｃｈｉｆｆ碱药物的抗菌作用冯英，刘义，谢昌礼，屈松生，乐芝凤，冯长建，沈昊宇，张香才（武汉大学化学系武汉４３００７２）（华中师范大学化学系武汉）关键词Ｓｃｈｉｆｆ碱药物，微量热法，产气杆菌Ｓｃｈｉｆｆ碱及其金属配合物具有抗病毒抗菌等生物...     

微量热研究几种新型吡啶酰胺希夫碱对大肠杆菌的抑制作用

用微量热研究一系列新型吡啶酰胺希夫碱对大肠杆菌的抑制作用, 不同的吡啶酰胺希夫碱衍生物对大肠杆菌生长的抑制作用不同. 通过热动力学模型计算得到生长速率常数(k)和抑制率(I), 我们获得了吡啶酰胺希夫碱衍生物的抗菌作用效果. 通过药物作用于细菌处于生长对数期的实验发现, 有两种化合物(F和G)对大肠杆菌生长有非常好的抑制作用, 他们的半抑制浓度(IC50)分别是0. 106 和0. 113 g/L, 但是药物对大肠杆菌的无氧发酵过程抑制作用比较差. 通过进一步分析药物结构与药物半抑制浓度, 我们发现: 希夫碱衍生物的亲水性对其抗菌活性有很大的影响, 这主要是由细菌的细胞膜结构不同所致. 对希夫碱及其碱衍物的结构与抗菌活性关系进行了初步探讨, 它们对大肠杆菌的抗菌活性顺序为: F＞G＞C＞D＞E＞B＞A.     

Schiff碱钴配合物的固相合成及其氧合性能

以苯甲醛缩多胺Schiff碱为配体与不同阴离子钴盐通过固相反应合成了6个Schiff碱钴配合物.采用UV,IR,元素分析,摩尔电导率,热分析等方法研究了配合物在室温下与O2的作用,初步探讨了钴盐阴离子对配合物氧合性能的影响.     

Schiff碱非铂抗癌络合物初步筛选的荧光法研究

依据药物与DNA发生相互作用能抑制DNA的复制、合成和增殖且这种作用在体内与在体外的一致性,用荧光探剂溴化乙锭(EB,EthBr)示踪药物/DNA作用而提出了荧光筛选新方法。该法具有可靠性强、灵敏度高、操作简便、耗费很小、周期较短等特点,适合于抗癌药物的初步筛选。以所合成的Schiff碱非铂抗癌络合物为例,考察了方法的可行性,并进一步确定了Schiff碱络合物与DNA的结合常数K_M,发现其大小与抗癌活性顺序相一致。这一结果为解释络合物抗癌作用的生化基础提供了初步依据,同时还说明络合有利于抗癌并以载体或整体起作用。     

邻香兰素对甲苯胺Schiff碱稀土配合物的制备和表征

前文曾报道了香兰素(3-甲氧基-4-羟基苯甲醛)与对甲基苯胺的Schiff碱稀土配合物。本文讨论邻香兰素(2-羟基-3-甲氧基苯甲醛)与对甲基苯胺的Schiff碱稀土配合物[LnL_2Cl·2H_2O]Cl_2(Ln:ce,Pr,Nd,Sm,Eu,Gd,Dy;L:Schiff碱)的制备和表征。 1 实验 1.1 配合物的制备 按文献方法,用等摩尔比的邻香兰素与对甲基苯胺在无水乙醇中先制成Schiff碱,然后按摩尔比1:2将稀土氯化物LnCl_3·nH_2O的无水乙醇溶液滴加到     

邻香兰素氨基酸Schiff碱化合物的合成及构象研究

Schiff碱是指含有亚甲氨基－PC＝N－的化合物,这类化合物因Schiff于1864年首先发现而得名。一些Schiff碱及其过渡金属配合物对肿瘤和病菌有一定的抑制作用^[1-3]。1970年,Hodnett^[4,5]制得几种Schiff碱,实验发现它们对老鼠肌肉内的Walker206瘤有抑制生长的作用,它们和某些金属形成的螯合物效果更好。Schiff碱配体可以作为螯合剂、生物活性剂、分析试剂和催化剂等,在科学研究和化工生产中有着广泛应用^[6,7]。本文报道一类新型的Schiff碱－邻香兰素氨基酸化合物的合成和构象研究,采用分子动力学模拟退火搜索方法对4人邻香兰素Schiff碱化合物的不同构型分子进行了构象研究,在搜索出的系列低能构象中分别找出全局最低能量构象,以此为初始构象进行了PM3量子化学计算。4个化合物的分子骨架结构如图1所示。     

Polymer-anchoring Schiff base ligands and their metal complexes: Investigation of their electrochemical,photoluminescence, thermal and catalytic properties

In this study, we prepared three polymer-anchored Schiff base ligands and their Cu(II), Co(II) and Ni(II) transition metal complexes. For this purpose, we synthesized three Schiff base ligands from the reaction of 2,4-dihydroxybenzaldehyde with diamines in the ethanol solution and characterized by the analytical and spectroscopic methods. We investigated the electrochemical and photophysical properties of the free Schiff base ligands in different solvents and concentrations. In the electrochemical studies, we found that the ligands show the reversible and irreversible redox processes. In order to obtain the polymer-anchored ligands, we used Merrifield’s peptide resin (PS) as solid support. The surface morphologies of the polymer anchored Schiff base ligands were done with the scanning electron microscopy (SEM). We did alkene epoxidation and alkane oxidation reactions of the metal complexes and used the cyclohexene, styrene, cyclohexane and cyclooctane as the substrate and they show the low catalytic activity. The metal complexes have no selectivity in the oxidation reactions. The polymer anchored Schiff base ligands and their metal complexes have high thermal stability at the higher temperatures.     

Polymer supported catalysts for oxidation of phenol and cyclohexene using hydrogen peroxide as oxidant

Polymer supported transition metal complexes of N,N′-bis (o-hydroxy acetophenone) hydrazine (HPHZ) Schiff base were prepared by anchoring its amino derivative Schiff base (AHPHZ) on cross-linked (6 wt%) polymer beads and then loading iron(III), copper(II) and zinc(II) ions in methanol. The loading of HPHZ Schiff base on polymer beads was 3.436 mmol g⁻¹ and efficiency of complexation of polymer anchored HPHZ Schiff base for iron(III), copper(II) and zinc(II) ions was 83.21, 83.40 and 83.17%, respectively. The efficiency of complexation of unsupported HPHZ Schiff base for these metal ions was lower than polymer supported HPHZ Schiff base. The structural information obtained by spectral, magnetic and elemental analysis has suggested octahedral and square planar geometry for iron(III) and copper(II) ions complexes, respectively, with paramagnetic behavior, but zinc(II) ions complexes were tetrahedral in shape with diamagnetic behavior. The complexation with metal ions has increased thermal stability of polymer anchored HPHZ Schiff base. The catalytic activity of unsupported and polymer supported HPHZ Schiff base complexes of metal ions was evaluated by studying the oxidation of phenol (Ph) and epoxidation of cyclohexene (CH). The polymer supported metal complexes showed better catalytic activity than unsupported metal complexes. The catalytic activity of metal complexes was optimum at a molar ratio of 1:1:1 of substrate to oxidant and catalyst. The selectivity for catechol (CTL) and epoxy cyclohexane (ECH) in oxidation of phenol and epoxidation of cyclohexene was better with polymer supported metal complexes in comparison to unsupported metal complexes. The energy of activation for oxidation of phenol (22.8 kJ mol⁻¹) and epoxidation of cyclohexene (8.9 kJ mol⁻¹) was lowest with polymer supported complexes of iron(III) ions than polymer supported Schiff base complexes of copper(II) and zinc(II) ions.     

Polymer Supported Schiff Base Complexes of Iron(III), Cobalt(II) and Nickel(II) Ions and their Catalytic Activity in Oxidation of Phenol and Cyclohexene

The polymer supported transition metal complexes of N,N′‐bis (o‐hydroxy acetophenone) hydrazine (HPHZ) Schiff base were prepared by immobilization of N,N′‐bis(4‐amino‐o‐hydroxyacetophenone)hydrazine (AHPHZ) Schiff base on chloromethylated polystyrene beads of a constant degree of crosslinking and then loading iron(III), cobalt(II) and nickel(II) ions in methanol. The complexation of polymer anchored HPHZ Schiff base with iron(III), cobalt(II) and nickel(II) ions was 83.30%, 84.20% and 87.80%, respectively, whereas with unsupported HPHZ Schiff base, the complexation of these metal ions was 80.3%, 79.90% and 85.63%. The unsupported and polymer supported metal complexes were characterized for their structures using I.R, UV and elemental analysis. The iron(III) complexes of HPHZ Schiff base were octahedral in geometry, whereas cobalt(II) and nickel(II) complexes showed square planar structures as supported by UV and magnetic measurements. The thermogravimetric analysis (TGA) of HPHZ Schiff base and its metal complexes was used to analyze the variation in thermal stability of HPHZ Schiff base on complexation with metal ions. The HPHZ Schiff base showed a weight loss of 58% at 500°C, but its iron(III), cobalt(II) and nickel(II) ions complexes have shown a weight loss of 30%, 52% and 45% at same temperature. The catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in presence of hydrogen peroxide as an oxidant. The supported HPHZ Schiff base complexes of iron(III) ions showed 64.0% conversion for phenol and 81.3% conversion for cyclohexene at a molar ratio of 1∶1∶1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 55.5% conversion for phenol and 66.4% conversion for cyclohexene at 1∶1∶1 molar ratio of substrate to catalyst and hydrogen peroxide. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 90.5% and 96.5% with supported HPHZ Schiff base complexes of iron(III) ions, but was found to be low with cobalt(II) and nickel(II) ions complexes of Schiff base. The selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was different with studied metal ions and varied with molar ratio of metal ions in the reaction mixture. The selectivity was constant on varying the molar ratio of hydrogen peroxide and substrate. The energy of activation for epoxidation of cyclohexene and phenol conversion in presence of polymer supported HPHZ Schiff base complexes of iron(III) ions was 8.9 kJ mol^?1 and 22.8 kJ mol^?1, respectively, but was high with Schiff base complexes of cobalt(II) and nickel(II) ions and with unsupported Schiff base complexes.     

Catalytic activities of polymer‐supported metal complexes in oxidation of phenol and epoxidation of cyclohexene

The metal complexes of N, N′‐bis (o‐hydroxy acetophenone) propylene diamine (HPPn) Schiff base were supported on cross‐linked polystyrene beads. The complexation of iron(III), copper(II), and zinc(II) ions on polymer‐anchored HPPn Schiff base was 83.4, 85.7, and 84.5 wt%, respectively, whereas the complexation of these metal ions on unsupported HPPn Schiff base was 82.3, 84.5, and 83.9 wt%. The iron(III) complexes of HPPn Schiff base were octahedral in geometry, whereas copper(II) and zinc(II) ions complexes were square planar and tetrahedral. Complexation of metal ions increased the thermal stability of HPPn Schiff base. Catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in the presence of hydrogen peroxide. The polymer‐supported HPPn Schiff base complexes of iron(III) ions showed 73.0 wt% conversion of phenol and 90.6 wt% conversion of cyclohexene at a molar ratio of 1:1:1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 63.8 wt% conversion for phenol and 83.2 wt% conversion for cyclohexene. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 93.1 and 98.3 wt%, respectively with supported HPPn Schiff base complexes of iron(III) ions but was lower with HPPn Schiff base complexes of copper(II) and zinc(II) ions. Activation energy for the epoxidation of cyclohexene and phenol conversion with unsupported HPPn Schiff base complexes of iron(III) ions was 16.6 kJ mol^?1 and 21.2 kJ mol^?1, respectively, but was lower with supported complexes of iron(III) ions. Copyright © 2007 John Wiley & Sons, Ltd.     

New metal(II) complexes with ceftazidime Schiff base

Complexes of Co(II), Ni(II) and Cu(II) with the Schiff base (LH) derived from ceftazidime and salicylaldehyde were synthesized. The proposed structures of the new metal complexes based on the results of elemental analyses, molar conductivity, IR, DRUV and ¹H NMR spectra, effective magnetic moment and thermal analysis were discussed. The surface morphology of Schiff base and metal complexes was studied by SEM. The composition of the metal complexes was ML₂, where L is the deprotonated Schiff base ligand and M = Co(II), Ni(II) and Cu(II). IR spectral data indicated the Schiff base ligand being bidentately coordinated to the metallic ions with N and O atoms from azomethine and phenolic groups. All the complexes have square-planar geometry and are nonelectrolytes. The thermal analysis recorded that TG, DTG, DTA and DSC experiments confirmed the assigned composition and gave information about the thermal stability of complexes in dynamic air atmosphere. Theoretical investigation of the molecular structure of Schiff base ligand and its complexes was studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. The newly synthesized complexes were tested for in vitro antibacterial activity against selected Gram-negative and Gram-positive bacterial strains, and they exhibited an antibacterial activity superior to that of the Schiff base ligand.     

席夫碱及其金属配合物的合成及生物活性研究进展

席夫碱及其金属配合物具有独特的抗菌、抗肿瘤和抗氧化等生物活性.为筛选高效低毒的药物,人们合成了大量不同类型的席夫碱及其金属配合物并对其生物活性进行了研究.本文综述了近年来席夫碱及其金属配合物的合成,以及在抗菌、抗氧化、抗肿瘤等方面生物活性的研究进展,并为进一步研究其在医药领域的应用提供了信息支持.     

Synthesis,spectroscopic, DNA cleavage and antibacterial activity of binuclear schiff base complexes

The binuclear Schiff base complexes are formed newly using different transition metals at their stable oxidation state as Cu(II), Ni(II), and VO(II). 3,3′,4,4′-tetraminobiphenyl and 2-aminobenzaldehyde were condensed to form a new Schiff base ligand having an two N₄ group responsible for better chelating to the metal centers. The ligand and their complexes have been established by analytical, spectral and electrochemical data. The interaction studies of the complexes with CT-DNA were carried out using cyclic voltammetry, viscosity measurements and fluorescence spectroscopy. The free ligand and their metal complexes were screened for their antimicrobial activities against the following species: Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus. A comparative study of minimum inhibitory concentration (MIC) values of the Schiff base and its complexes indicate that the metal complexes exhibit higher antibacterial activity than the free ligand.     

Chromone-based Schiff base metal complexes as catalysts for catechol oxidation: Synthesis,kinetics and electrochemical studies

Two new Schiff base ligands with chromone moiety and their transition metal complexes were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conductance and TGA analyses, FT IR, UV-Vis, NMR and mass spectroscopy. All the complexes synthesized have been investigated as functional models for catechol oxidase (catecholase) activity by employing 3,5-di-tert-butylcatechol as a model substrate. The two mononuclear copper(II) and two mononuclear iron(II) complexes show catecholase activity with turnover (k_cat) numbers lying in the range 27.2–1328.4 h^?1. According to the kinetic measurement results, the rate of catechol oxidation follows first order kinetics and iron(II) complexes were found to have higher catalytic activity than those of copper(II) complexes. Electron-donating substituent on Schiff base ligand enhanced the catalytic activity of metal complexes while the electron-withdrawing substituent led to a decrease in activity. The electrochemical properties of two Schiff bases and their metal complexes were also investigated by Cyclic Voltammetry (CV) using glassy carbon electrode (GCE) at various scan rates. Electrochemical processes of all the compounds were observed as irreversible.     

新型Schiff碱双核配合物的合成及光谱特征

首次报道了新型Schiff碱双核配合物-双[N,N"-亚烃基-2,2'(苯亚甲基)二(3,4-二甲基吡咯-5醛缩亚胺)]合双锰及双铁配合物的合成方法及光谱特征。