Cobalt(II) Salen Complex with Two Aza-crown Pendants and Its Analogues as Synthetic Oxygen Carriers

Introduction Synthetic oxygen carriers1 are of great interest as models to mimic oxygen carrying metalloenzymes2 for oxygen storage and transport. The cobalt(II) complexes of Schiff bases, such as Salen and its analogues, have been the first and the most extensively investigated due to their structural similarity to those found in biological systems.3,4 However, these complexes are easy to dimerize and lose activities after oxygen molecule ab-sorption.5 Avdeef and coworkers6 demonstrated tha…     

Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt（Ⅱ） Complexes Containing Benzoaza-15-crown-5

Three novel Schiff base cobalt（Ⅱ） complexes containing benzoaza-15-crown-5, CoL^1, CoL^2 and CoL^3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester （PNPP, p-nitrophenyl picolinate） as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt（Ⅱ） complexes. The CoL^3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS^-. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ·mol^-1, respectively.     

氮杂冠醚取代的单Schiff碱的合成及其钴(Ⅱ)配合物的氧加合性能

由苯并 10 氮杂 15 冠 5出发 ,经 2～ 4步反应合成了氮杂冠醚取代的单Schiff碱HL1,HL2及其异构体HL3 ,HL4.并以元素分析 ,IR ,1 HNMR和MS进行了表征 .在不同温度下 ,测定了它们的钴 (Ⅱ )配合物的氧合反应平衡常数及热力学参数ΔH°和ΔS° ,并与合成的非冠醚类似物CoL2 5 ,CoL2 6和CoL2 7比较 ,考察了配体芳环上取代的氮杂冠醚环及其取代位置对氧加合性能的影响     

Synthesis, Crystal Structure, Properties and Thermoanalysis of Complexes of Cu（Ⅱ） and Ni（Ⅱ） with Taurine-5-chlorosalicylaldelyde Schiff Base

The reactions of transition metal salts with taurine 5‐chlorosalicylaldelyde Schiff base gave two complexes [Ni(TCSSB)(H₂O)₃].H₂O (1) and [Cu(TCSSB)(H₂O)₂]₂[Cu(TCSSB)₂].6H₂O (2) (TCSSB=taurine‐5‐chlorosalicylaldelyde Schiff base), which were characterized by elemental analysis and X‐ray diffraction analysis. The complex 1 crystallized in monoclinic system with space group P2 ₁/c, and a=1.4816(2) nm, b=1.3953(2) nm, c= 0.7466(1) nm, β= 100.499(3)°, V=1.5176(4) nm³, Z=4, and an infinite 3‐D network structure was formed by hydrogen bonds among sulfo group, crystal water and coordinated water. Complex 2 crystallized in triclinic system with space group P1 , with the cell parameters: a = 0.6413(2) nm, b= 1.4596(3) nm, c= 1.6188(4) nm, a= 102.473(5)°, β= 98.979(4)°, γ=101.739°, V=1.4165(6) nm³, Z=1. The coordination environment between Cu(1) and Cu(2) is different. Cu(1) is slightly distorted square pyramidal while Cu(2) is distorted square‐plane. The complex 1 is mononuclear while the complex 2 is made up of two coordinated subunits, namely [Cu(TCSSB)₂] and [CU(TCSSB)(H₂O)₂]₂. Besides that the TG‐DTG of the complex 1 was analyzed, the thermal decomposition reaction of the complex was studied under a non‐isothermal condition by TG‐DTG. The TG and DTG curves indicate that the complex was decomposed in three stages: .     

Synthesis and Structure of a New Bicadmium （Ⅱ） Complex with Macrocyclic Hexaaza Bearing Hydroxyethyl Pendants

1 INTRODUCTION The cadmium(??) complexes have been exten-sively studied because of their potentially usefulproperties, such as toxicity research[1], catalysis[2],magnetism[3] and nonlinear optics[4]. A lot of studieson binuclear cadmium(??) pendant-ar…     

氮杂冠醚取代基对schiff碱锰(Ⅲ) 配合物催化苯乙烯环氧化反应的影响

合成并表征了苯并-10-氮杂-15-冠-5或吗啉基取代的单和双Schiff碱锰（Ⅲ）配合物MnL2^1Cl,MnL2^2Cl,Mnl^3Cl和MnL^4Cl．研究了它们作为仿P450模型化合物催化苯乙烯环氧化反应的性能,并考察了催化反应的动力学．结果表明,氮杂冠醚取代的Schifft碱锰（Ⅲ）配合物优于相应的吗啉基取代的Schiff碱锰（Ⅲ）配合物,且反应遵从Michaelis—Menten规律．这是由于具有特殊功能和空间构型的氮杂冠醚大环的引入。改善了催化中心周围的微环境,从而显著地提高了Schiff碱锰（Ⅲ）配合物的催化活性．     

Dioxygen Affinities and Catalytic Oxidation Performance of Cobalt （Ⅱ）Complexes with N—Aryl Hydroxamic Acid

The oxygenation of cobalt(Ⅱ) hydroxamates(CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined.The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.     

Syntheses and Crystal Structures of Ternary Complexes of Zinc（Ⅱ） and Cadmium（Ⅱ） with 3-Aminobenzoic Acid and 1,10-Phenanthroline

1 INTRODUCTION Benzoic acids with substituent of amino are a class of rigid ligands possessing several functional groups. When they coordinate to metal ions, versa- tile coordination modes will be presented with pre- sence of not only coordinate-covalent bonds but also hydrogen bonds. Besides, diverse coordination modes of carboxyl and rigid frame of benzene ring gua- rantee the stability of multi-dimensional structures of the synthesized metal complexes. Thus ligands of this class are o…     

Microwave Synthesis, Characterization and DNA-binding Properties of a New Cobalt（ Ⅱ ） Complex with 2,6-Bis（benzimidazol-2-yl）pyridine

A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol-2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis,electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra.     

p‐Nitrophenyl Picolinate Cleavage by Unsymmetrical Bis‐Schiff Base Manganese(III) and Cobalt(II) Complexes with Aza‐Crown Ether or Morpholino Pendants

The unsymmetrical bis‐Schiff base manganese(III) and cobalt(II) complexes with either benzo‐10‐aza‐crown ether pendants (MnL¹Cl, MnL²Cl) or morpholino pendant (MnL³Cl, CoL³) have been employed as models for hydrolase by studying the kinetics of their hydrolysis reactions with p‐nitrophenyl picolinate (PNPP). A kinetic model of PNPP cleavage catalyzed by these complexes is proposed. The effects of complex structures and reaction temperature on the rate of PNPP hydrolysis have been examined. All four complexes exhibit high catalytic activity and the rate increases with pH under 25°C. The complexes of ligands containing a crown ether group exhibit higher catalytic activities than the non‐crown analogues. The catalytic activity of the complexes follows the order Mn(III)>Co(II) under the same ligands.     

Synthesis of N—（4—Salicylideneiminoaryl）monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt（Ⅱ）Complexes

The Schiff base‐containing pendant monoaza crown ether HL¹, HL², HL³ and HL⁴ have been synthesized by condensation of salicylaldehyde with N‐(4‐aminoaryl) monoaza crown ethers, which were prepared conveniently from 4‐nitro‐N, N‐di(hydroxyethyl) aniline or 4‐nitrobenzyl chloride via cyclization or condensation and reduction. The structures of HL¹—HL⁴ were verified by ¹H NMR, IR spectra, MS and elemental analysis. Moreover, the oxygenation constants (KO2) and thermodynamic parameters (δH⁰ and δS⁰) of their cobalt(II) complexes were determined in the range of ?5 °C to 25 °C, and the effect of crown ring bonded to a Schiff base on the dioxygen affinities of cobalt(II) complexes was also observed as compared to the uncrowned analogue (CoL).     

氮杂冠醚或吗啉基取代的单Schiff碱配合物催化α-吡啶甲酸对硝基苯酯水解

两种含5-取代苯并-10-氮杂-15-冠-5的Schiff碱锰(III)、钴(II)配合物( , )及其吗啉基取代的类似物( , ) 用于催化α-吡啶甲酸对硝基苯酯(PNPP)水解。探讨了氮杂冠醚Schiff 碱配合物催化PNPP水解的动力学和机理;提出了配合物催化PNPP水解的动力学模型;考察了配合物结构、反应温度、缓冲溶液pH值等对PNPP水解反应的影响。结果表明,在25℃条件下随着缓冲溶液pH值的增大,催化PNPP水解速率提高;含取代苯并-10-氮杂-15-冠-5的Schiff碱配合物表现出更高的催化活性。根据阿累尼乌斯公式和不同温度下的表观一级常数求出水解反应的表观活化能。     

Synthesis of N-(4-Salicylideneiminoaryl)monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt(II) Complexes

IntroductionSchiffbasesandtheirmetalcomplexeshavebeenap pliedwidelyinthefieldofcatalyticchemistry ,liquidcrystalsandphotochromism .1 3ManySchiffbaseligandscontainingcrownetherpossessdifferentrecognitionsitesforbothalkaliandtransitionmetalguestcations,4 forexample ,theNa(I)orK(I) /Co(II)hetero nuclearcomplexesofcrownedSchiffbasecanbindoxygenmolecule (O2 )toformstablesoliddioxygenadducts .5 7Gebbinkandco workershavereportedaK(I) /Cu(II)sandwichcomplexwhichcanacceleratethefor mationofdioxyg…     

Antibacterial activity of transition metal complexes containing a tridentate NNO phenoxymethylpenicillin‐based Schiff base. An anti‐MRSA iron (II) complex

Transition metal complexes containing a phenoxymethylpenicillin‐derived Schiff base (HL) 3 obtained from the condensation of phenoxymethylpenicillin (PMP) 1 , with 1,2‐diaminobenzene 2 , were prepared. Spectroscopic and physicochemical techniques, namely, UV–Vis, FT‐IR, ¹H‐NMR, EPR, mass spectrometry, magnetic susceptibility, molar conductance, DFT studies, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on the characterization studies, the general formulae [ML (OAc)(H₂O)₂] where M = Fe 4 , Co 5 , Ni 6 , Cu 7 , and Zn 8 , were proposed for the complexes. The Schiff base ligand 3 behaved as a monoanionic tridentate NNO chelating agent. On the basis of magnetic and spectral data an octahedral geometry for all the complexes was suggested. Schiff base ligand 3 , and the metal complexes 4 – 8 were tested against G(+) or bactericidal activity by agar disc diffusion method and minimal inhibitory concentration (MIC). The results were compared with the activity of the standard drug PMP 1 . In vitro bacterial viability revealed that 3  had similar activity than 1 and exhibited modification in its bactericidal activity when formed metal complexes. It was found that the complexes 4 , 6 and 7 exhibited much better bactericidal activity than 1 against methicillin‐resistant Staphilococcus Aureus (MRSA) being complex 4 the most promising compound showing a MIC value of 0.042 μmol/ml.     

9‐Benzylidene‐9H‐fluorene Derivatives Linked to Monoaza‐15‐crown‐5: Synthesis and Metal Ion Sensing

Two kinds of novel styryl chemosensory 2‐FMNC and 3‐FMNC, were designed and synthesized by an apporiate introduction of 9‐benzylidene‐9H‐fluorene group as fluorophore with the aim at avoiding photoisomerisation. These 9‐benzylidene‐9H‐fluorene derivatives showed the similar selectivity and sensitivity upon addition of metal ions. The sensitivity of FMNC to alkaline earth metal ions was Ba²⁺>Sr²⁺>Ca²⁺≈Mg²⁺.     

Bulk solvent‐free melt ring‐opening polymerization of L‐lactide catalyzed by Cu(II) and Cu(II)–Nd(III) complexes of the Salen‐type Schiff‐base ligand

A monometallic (Cu²⁺, 1) and a bimetallic (Cu²⁺ Nd³⁺, 2) Salen‐type Schiff‐base complexes with different reactive species, could efficiently catalyze the bulk solvent‐free melt ring‐opening polymerization (ROP) of L ‐lactide. Especially for the bimetallic complex 2, the involvement of rare earth ion was important and influential to the catalytic behaviors. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Characterization of New Macrocyclic Cu（Ⅱ） Complexes from Various Diamines, Copper（Ⅱ） Nitrate and 1,4-Bis（2-formylphenoxy）butane

Six new macrocyclic complexes were synthesized by a template reaction of 1,4-bis（2-formylphenoxy）butane with diamines and Cu（NO3）2·3H2O and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The metal to ligand molar ratios of the Cu（Ⅱ） complexes were found to be 1 ： 1. The Cu（Ⅱ） complexes are 1 ： 2 electrolytes as shown by their molar conductivities （∧m） in DMF at 10^-3 mol·L^-1. Due to the existence of free ions the Cu（Ⅱ） complexes are electrically conductive. Their configurations were proposed to be probably distorted octahedral.     

Design,Synthesis and Antitumor Activity of Asymmetric Bis(s‐triazole Schiff‐base)s Bearing Functionalized Side‐Chain

1‐Amino‐2‐pyrid‐3‐yl‐5‐(2‐benzoylethylthio)‐s‐triazole ( 1 ) was condensed with 1‐amino‐3‐mercapto‐5‐ [(un)substituted phenyl]‐s‐triazoles and subsequently substituted with chloroacetic acid to afford bis‐s‐triazole sulfanylacetic acid mono‐Schiff bases ( 3a – 3e ), which were condensed with 9‐formylanthracene to produce asymmetric bis(s‐triazole Schiff base) sulfanylacetic acids ( 4a – 4e ). The structures of new synthesized compounds were characterized by elemental analysis and spectral data, and their in vitro antitumor activity against L1210, CHO and HL60 cell lines was evaluted via the respective IC₅₀ values by methylthiazole trazolium (MTT) assay.