Catalytic Effect of Transition Metal Complexes of Triaminoguanidine on the Thermolysis of Energetic NC/DEGDN Composite

The transition metal complexes of triaminoguanidine(TAG-M,where M=Cobalt(Co)or Iron(Fe))have been prepared.The catalytic effect of these complexes on the thermolysis of energetic composite based on nitrocellulose and diethylene glycol dinitrate,has been investigated.Extensive characterization of the resulting energetic composites was carried out using scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and differential scanning calorimetry(DSC).Isoconversional kinetic analysis was performed to determine the Arrhenius parameters associated with the thermolysis of the elaborated energetic formulations.It is found that TAG-M complexes have strong catalytic effect on the thermo-kinetic decomposition of NC/DEGDN by decreasing the apparent activation energy and significantly increased the total heat release.The models that govern the decomposition processes are also studied,and it is revealed that different reaction processes are accomplished by introduction metal complexes of triaminoguanidine.Overall,this study serves as a valuable reference for future research focused on the investigation of catalytic combustion features of solid propellants.

Synthesis and Physico-Chemical Characterizations of Novel Hydrazone Ligands and Their Metal Complexes against Hormone-Dependent and Independent Cancers

This work deals with the synthesis and physicochemical characterizations of a new group of novel retinoidal ligands and their metal complexes. Their in vitro anti-proliferative activities have shown that ligand L1 is effective against human breast cancer BT-20 and MCF-7 cell lines. At the same time, compound L2 exerts its effect on human prostate cancer PC-3 and human breast cancer MDA-MB-231 and MCF-7 cell lines respectively. The retinoid ligands exert their pleiotropic action toward retinoic acid receptors (RARs) than their metal complexes but all compounds exhibit concentration-dependent.

Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin （BSA）, which afforded BSA binding Schiff-base metal complexes （BSA-SalGluM, M=Cu, Co, Ni, Zn）. The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

Preparation and antioxidant activity of albumin binding Salen Schiff-base metal complexes

A kind of novel biopolymer antioxidant (BSA/HOSalenM, M=Co, Mn, Zn) is prepared with conjugation, which increases the antioxidant activity of the bovine serum albumin (BSA). The conjugations have been characterized by IR spectra, UV-Vis spectra, Fluorescence spectra, Circular dichroism (CD) spectra and Native-PAGE. The BSA is used as a biopolymer scaffold, and the insoluble Salen Schiff-base metal complexes HOSalenM make axial coordination with the amino acid residues of the BSA. The structure of the BSA is unchanged when the binding rate of HOSalenCo is less than 10. The HOSalenCo conjugations show an excellent hydroxyl radical (·OH) scavenging activity, and the activity (EC50 ) of BSA/HOSalenCo(10) (BSA : HOSalenCo=1 : 10) is improved by two orders of magnitude compared with the BSA, while the activity of the BSA/HOSalenMn is weak and the BSA/HOSalenZn shows no scavenging activity.

Preparation and Catalysis of Aminomethylated Polystyrene Supported Unsymmetrical Schiff-Base Metal Complexes for the Oxidation of Cyclohexene

1 Results The dominant position of molecular oxygen as the oxidant for bulk chemical oxyfunctionalizations is due to the fact that it is the only economically and environmentally friendly feasible oxidant for large scale processing.But molecular oxygen is not better oxidant than others,such as PhIO,NaOCl,H2O2,alkyl hydroperoxides,percarboxylic acids,magnesium monoperoxyphthalate.So we have to select high reactivity and general utility catalyst.The oxidation of hydrocarbons catalyzed by transition metal ...

A Theoretical Study of Tris-(o-benzoquinonediimine)-First-Row Divalent Transition Metal Complexes

The ligand o-phenylenediamine (opda) and its oxidized form, o-benzoquinonediimine (bqdi), act as a fascinating candidate coordinating toward transition metal ions leading to the photochemical hydrogen production in absence of photosensitizers. Herein, we report the systematic study of the interaction between the oxidized form bqdi ligand, tris-(o-benzoquinonediimine) with divalent first-row transition metal series using DFT calculations. The lowest energy structures, bond length, binding energies, frontier molecular orbital analysis, natural bond orbitals, and global reactivity descriptor were calculated using B3LYP/6-311G(d,P) level of theory. The time dependent-DFT at the CAM-B3LYP/6-311+G(d,p) level of theory was applied to determine the electronic structures and the optical spectra. The theoretical binding trend of the divalent first-row transition metal series is decreasing as follows: Cu >Ti > V > Co > Ni > Fe > Cr > Zn >Mn. Among them, the binding potency of iron (II) by the bqdi ligand was not predominantly sturdy as compared to other first-row divalent transition metal ions. The origin of strong coordination with Fe(II) is attributed to its extra capability to induce covalent coordination of bqdi ligands. The complex exhibited two strong peaks at 370 nm and 452 nm, due to the HOMO-3 to LUMO+1 and HOMO-1 to LUMO transitions, respectively. Natural bond orbital analysis showed that the major interaction happens between the N lone pair electrons of the ligand with an anti-bonding orbital of metal ions, in which Ti showed the highest interaction energy than other metal ions. The present systemic DFT study of bqdi ligands with the first-row transition metals strongly encourages the future establishment of photochemical hydrogen production in absence of photosensitizers.

Probing electronic structures of transition metal complexes using electron paramagnetic resonance spectroscopy

Electron paramagnetic resonance(EPR)or electron spin resonance(ESR)has been widely employed to characterize transition metal complexes.However,because of the high degree of complexity of transition metal EPR spectra,how to extract the underlying electronicstructure information inevitably poses a major challenge to beginners,in particular for systems with S>1/2.In fact,the physical principles of transition metal EPR have long been well-established and since 1970s a series of dedicated voluminous monographs have been published already.Not surprisingly,they are not appropriate stating points for novices to grasp a panorama of the profound theory prior to scrutinizing in-depth references.The present review aims to fill this gap to provide a perspective of transition metal EPR and unveil some peculiar subtleties thereof on the basis of our recent work.

SVNTHESES AND CHARACTERIZATION OF TWO HIGH VALENCE VANADIUM COMPLEXES (?) SCHIFF-BASE LIGAND WITH RICH PHENOLATE OXVGEN AND THEIR CONVERSION

Two vanadium complexes of schiff base vith rich phenolate oxygen,o-(?)-salicylideneamino- methylphenol,had been synthesized and characterized.One is a V(Ⅳ)complex with an interaction via vanadyl oxygen and the other is a novel dinuclear V(V,V)complex with an oxo bridge.The conversion between the two complexes had been discussed.

Inhibition of cysteine protease papain by metal ions and polysulfide complexes,especially mercuric ion

Aim Cysteine proteases are closely associated with many human and non-human pathological processes and are potential targets for metal ions especially Hg^2＋ and the related species. In the present work, on the basis of to the general study on the effects of some metal ions on the activity of papain, a well-known representative of cysteine protease family, the inhibitory effects of Hg^2＋ and polysulfide complexes were studied. Results All the metal ions tested （Hg^2＋, Cu^2＋, Ag^＋, Au^3＋, Zn^2＋, Cd^2＋, Fe^3＋, Mn^2＋, Pb^2＋, Yb^3＋） inhibit the activity of papain anda good correlation between the inhibitory potency and softness-and-hardness was observed. Among the metals, Hg^2＋ was shown to be a potent inhibitor of papain with a Kiof 2 × 10^-7 mol·L^-1 among. Excessive amounts of glutathione and cysteine could reactivate the enzyme activity of papain deactivated by Hg^2＋. These evidences supported that Hg^2＋ might bind to the catalytic site of papain. Interestingly, Hg （Ⅱ） polysulfide complexes were for the first time found to inhibit papain with a Ki of 7 × 10^-6 mol·L^-1, whose potency is close to a well known mercury compound, thimerosal （Ki=2.7 × 10^-6）. In addition, Hg （Ⅱ） polysulfide complexes exhibit good permeability （ 1.9 × 10-5 cm· s^-1） to caco-2 monolayer. Conclusion These results suggested that mercury polysulfide complexes might be potential bioactive species in the interaction with cysteine proteases and other- SH-content proteins, providing a new clue to understand the mechanism of the toxicological and pharmacological actions of cinnabar and other insoluble mercury compounds.

Liquid Metal-Based Self-Healable and Elastic Conductive Fiber in Complex Operating Conditions

Flexible conductive fibers are essential for wearable electronics and smart electronic textiles.However,in complex operating conditions,conductive fibers will inevitably fracture or damage.Herein,we have developed an elastic conductive self-healable fiber(C-SHF),of which the electrical and mechanical properties can efficiently heal in a wide operating range,including room temperature,underwater,and low temperature.This advantage can be owed to the combination of reversible covalent imine bond and disulfide bond,as well as the instantaneous self-healing ability of liquid metal.The C-SHF,with stretchability,conductivity stability,and universal self-healing properties,can be used as an electrical signal transmission line at high strain and under different operating conditions.Besides,C-SHF was assembled into a double-layer capacitor structure to construct a self-healable sensor,which can effectively respond to pressure as a wearable motion detector.

Density Functional Theory Study on La Complex with Schiff-base as Building Block

Quantum density functional theory （DFT） results are reported for the building block [LaL^1（NO3）] of La complex [LaL^1（NO3）]NO3·5H2O （L^1 = （CH3）2CHCH2CH（NCHC4H3O）COO^-）. The structure was optimized and the calculation results show that the lanthanum ion is coordinated by one nitrogen atom and three oxygen atoms of L^1 and two oxygen atoms of nitrate ion. The bond length of La-N is 0.2637 nm and the average length of La-O is 0.2526 nm, which are consistent with the literatures. In addition, the stabilities, electronic structural characteristics and IR spectra of the complex have been analyzed, which describe the coordination of lanthanum ion with other atoms in detail.

Highly active double metal cyanide complexes: Effect of central metal and ligand on reaction of epoxide/CO2

Various novel double metal cyanide （DMC） catalysts were successfully prepared by modifying the central metal （M） and one of cyanide ion （CN-） in Zna[M（CN）b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni（Ⅱ） DMC is a potential catalyst for alternating copolymerization of PO/CO2,and DMC catalysts based on Zn3[Co（CN）5X]2 （X = Br^- and N3^-） exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.

Metal 2-Hydroxy-1-Naphthaldehyde Thiosemicarbazone (Me-HNT) Complexes-A New Kind of Biomimic Enzyme Catalyst

Metal (Me=Fe(III), Mo(VI), Mn(II), Co(II), Ni(II), Zn(II) and Cu(II)) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes (MeHNT) were synthesized and used as mimic-enzyme catalysts to mimic the active group of horseradish peroxidase (HRP). The results showed that Fe-HNT, Mo-HNT are effective catalysts, which have similar catalytic activity as HRP. The sequence of catalytic activities of tested biomimic peroxidas is Mo-HNT > Fe-HNT > Zn-HNT > Ni-HNT > Mn-HNT. Among them, Fe-HNT is used as a mimic-enzyme catalyst in determination of ascorbic acid and glucose by coupling the catalytic reaction of glucose oxidase.

Synthesis of Schiff bases of naphtha[1,2-d]thiazol-2-amine and metal complexes of 2-(2'-hydroxy)benzylideneaminonaphthothiazole as potential antimicrobial agents

Objective： A series of 2-benzylideneaminonaphthothiazoles were designed and synthesized incorporating the lipophilic naphthalene ring to render them more capable of penetrating various biomembranes. Methods： Schiff bases were synthesized by the reaction of naphtha[1,2-d]thiazol-2-amine with various substituted aromatic aldehydes. 2-（2＇-Hydroxy）ben- zylideneaminonaphthothiazole was converted to its Co（Ⅱ）, Ni（Ⅱ） and Cu（Ⅱ） metal complexes upon treatment with metal salts in ethanol. All the compounds were evaluated for their antibacterial activities by paper disc diffusion method with Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bacteria. The minimum inhibitory concentrations of all the Schiff bases and metal complexes were determined by agar streak dilution method. Results： All the compounds moderately inhibited the growth of Cram positive and Gram negative bacteria. In the present study among all Schiff bases 2-（2＇-hydroxy）benzylideneaminonaphthothiazole showed maximum inhibitory activity and among metal complexes Cu（Ⅱ） metal complex was found to be most potent. Conclusion： The results obtained validate the hypothesis that Schiff bases having substitution with halogens, hydroxyl group and nitro group at phenyl ring are required for the antibacterial activity while methoxy group at different positions in the aromatic ring has minimal role in the inhibitory activity. The results also indicated that the metal complexes are better antibacterial agents as compared to the Schiff bases.

Synthesis and Liquid Crystal Properties of Transition Metal Complexes of Meso-tetra(4-n-myristyloxyphenyl)porphyrin

Transition metal complexes of meso-tetra(4-myristyloxyphenyl)porphyrin TMPPM [M =Mn, Fe, Co, Ni, Cu, Zn; TMPP=mesotetra(4-myristyloxyphenyl)porphyrin] have been synthesized and characterized by means of elemental analyses, UV-Vis spectra, infrared photoacoustic spectra, 1H NMR spectra, molar conductance and differential scanning calorimetry(DSC). The ligand and the Zn complex show liquid crystalline behavior. According to the DSC thermogram of the Zn complex, it exhibits a lower phase transition temperature -7.453 ℃ and a wide mesophase temperature span, 77 ℃.

Simultaneous Removal of Surfactant Template from MCM-41 and Implantation of Transition Metal Complexes into Mesopores with Supercritical Fluid

The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.

Ultra-deep Removal of Metal Ions from Coal Tar by Complexation:Experimental Studies and Density Functional Theory Simulations

As one of the important aspects of upgrading coal tar,the ultra-deep removal of metal ions via the complexation method was investigated by screening four complexing agents and performing density functional theory(DFT)simulations.Analysis of the compositions and contents of the metallic compounds in the coal tar revealed that the main components were iron and calcium naphthenates.Direct filtration reduced the mechanical impurity content from 0.24%to 0.0752%,indicating that most of the large particles could be easily removed.Among the four complexing agents,namely,acetic acid,oxalic acid,citric acid,and ethylenediaminetetraacetic acid,oxalic acid exhibited the best demetallization performance.The DFT simulations suggested that the high performance of oxalic acid originated from its 1:1 coordination mode,rigid dicarboxyl structure,and greater binding energy.

Synthesis and characterization of a novel schiff base metal complexes and their application in determination of iron in different types of natural water

A novel, simple approach to the synthesis of macrocyclic Schiff base ligand resulted from the condensation of bisaldehyde and ethylenediamine was prepared (7, 8, 15, 16, 17, 18-hexahydrodibenzo (a, g) (14) annulene) (L) and its complexes were synthesized and characterized using different physicochemical studies as elemental analysis, FT-IR, 1H NMR, conductivity, magnetic properties, thermal analysis, and their biological activities. The spectroscopic data of the complexes suggest their 1:1 complexe structures which are investigated by elemental analysis, FT-IR, 1H NMR, conductivity, magnetic properties, thermal analysis, and their biological activities. The spectroscopic studies suggested the octahedral structure for the all complexes. The spectroscopic data of the complexes suggest their structure in which (N2O2) group act as a tetradentate ligand and two chlorides as monodentate ligands. Also electronic spectra and magnetic susceptibility measurements indicate octahedral structure of these complexes. The synthesized Schiff base and its metal complexes also were screened for their antibacterial and antifungal activity. Here we report the effect of a neutral chelating ligand on the complexation with iron to determine it in different types of natural water using recovery test. The activity data show that the metal complexes to be more potent/ antibacterial than the parent Schiff base ligand against one or more bacterial species.

Synthesis and Crystal Structure of the Novel Chiral o-Hydroxyphenyloxazoline Metal Complexes

The chiral o-hydroxyphenyloxazoline ligands were synthesized and their metal complexes with Cu, Ni and Ti were prepared. The crystal structure of complex 2a formed by ligand 1a with Cu (molar ratio 2:1) was determined by single-crystal X-ray diffraction analysis, and it belongs to monoclinic, space group P21 with a = 11.679(2), b = 17.681(4), c = 12.838(3) ? b = 106.50(3), C26H32N2O4Cu, Mr = 500.08, V = 2541.8(9) 3, Z = 4, F(000) = 1052, Dc = 1.307 g/cm3, m = 0.892 mm-1, the final R = 0.0448 and wR = 0.0930 (I > 2s(I)). In the asymmetric unit of complex 2a, there exist two types of molecules which are self-associated by intermolecular O…Cu interactions, and 揹imeric complex?is thus formed. The distances of the Cu and O atoms of a pair of intermolecular coordinated molecules are 2.828 ?for Cu(1)…O(21) and 2.776 ?for Cu(2)…O(13), respectively. The coordination N and O atoms and the central Cu are slightly deviated from coplanarity.

Microwave Preparation and Spectroscopic Investigation of Binuclear Schiff Base Metal Complexes Derived from 2,6-Diaminopyridine with Salicylaldehyde

The binuclear Schiff base complexes prepared by condensation 2,6-diamino-pyridine and salicylaldehyde (LH) by using microwave and adding metal salts to ligand by same ratio. The Schiff base ligand was checked by infrared, electronic spectra and 1HNMR spectroscopy and prepared complexes characterized by molar conductivity, infrared, electronic spectra and susceptibility measurements. The values of molar conductivities reveal that the complexes are non-electrolytes, from obtained data of electronic spectra and magnetic moment, an octahedral geometry was suggested, coordinated to the metal ions in a manner with N donor sites of imine groups, and oxygen of phenolic OH group.