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.

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.

Recent advances on decomplexation mechanisms of heavy metal complexes in persulfate-based advanced oxidation processes

In some industrial wastewater,heavy metals combine with organic complexing agents to form heavy metal complexes(HMCs).These HMCs can be difficult to decompose and remove through conventional techniques due to their higher stability than free heavy metal ions.In recent years,persulfate based advanced oxidation processes(PS-based AOPs)have been recognized as a viable technique for HMCs degradation.Nevertheless,a comprehensive and in-depth understanding of the relevant HMCs decomplexation mechanisms in PS-based AOPs is still lacking.This review delineates the current progress of HMCs decomplexation in PS-based AOPs.We discuss the distinctions between the two widely used oxidant types in PS-based AOPs techniques.Moreover,we summarize and highlight the decomplexation mechanisms based on electron and energy transfer,and degradation pathways of HMCs.We also emphasize the effects of environmental water constituents,namely p H,inorganic ions,and natural organic matter(NOM),on HMCs decomplexation.Ultimately,we identify the existing challenges and perspectives that will steer the direction of advancing PS-based AOPs to remove HMCs.

Analysis of Equilibrium and Kinetics of Chromium-Fluoride Complexation from Spectroscopic Data via Chemometrics Methods

The complexation of Cr^3＋ with F^- undergoes a muhistep reversible process. An approach to research the involved equilibria and kinetics using suitable chemometrics methods to the online measured UV-Vis spectra is proposed. By investigating the equilibrium spectra of the complexes at different molar ratios of M to L（ metal to ligand） and 50 ℃, the result of Principal Component Analysis（PCA） shows that three complexes, ML, ML2 and ML3, can be formed under the research conditions. The spectrum of each complex was then analyzed and the accumulated equilibrium constants were calculated by applying Target Testing Factor Analysis（TITA）. Meanwhile, a reactive intermediate was observed before the formation of MLx during the specific kinetic study at 15℃. The equilibrium constant and spectrum of the intermediate as well as the rate constants were all resolved by using TTFA.

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.

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.

Metal-organic Coordination Architectures of Triazole-ligands: Syntheses, Structures and Luminescent Properties

Five new transitional metal complexes with 4,4′-bis（1,2,4-triazol-1-ylmethyl）- biphenyl （L1）, 1,4-bis（1,2,4-triazol-1-ylmethyl）naphthalene （L2） and 1-（1H-1,2,4-triazol-l-yl）- 3-phenyl-2-one （L3） were synthesized and characterized by elemental analysis, IR and X-ray diffraction. Complexes 1-3 have one-dimensional （1-D） chain structures, and L1 adopts a gauche-gauche conformation with the shortest N...N distance between the two N donors in complexes 1-3; however, L2 adopts a trans-gauche conformation in complex 4. Complex 5 is a mononuclear structure, and L3 adopts a monodentate coordination mode. The fluorescence properties of ligands L1 and complexe 1 have been investigated.

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 ℃.

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.

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.

Synthesis, Characterization and Biological Activity of Transition Metals with Schiff Base Derived from Adamantaneamineand o-Vanillin

Five new solid complexes were synthesized about transition metals with Schiff base（ L, C18H23NO2 ） derived from adamantaneamine and o-vanillin, and characterized by elemental analysis, molar conductance, infrared spectra, UV-vis spectra, thermal analysis. Their chemical formula are [ML2]（ClO4）2 （ M= Mn, Co, Ni, Cu, Zn）, and the coordination numbers are four, The antibacterial activity of Schiff base ligand and its complexes was studied.

Preparation and Aqueous Recognition of Metal Complex Imprinted Polymer Using N-vinyl-2-pyrrolidone as Functional Monomer

Using nickel（II） acetate.-2,2＇-dipyridyl complex as template and N-vinyl-2-pyrrolidone （NVP） as coordinate functional monomer,.a new kind of metal-compiexing template molecularly impnnted polymer （MIP） was prepared..The results of equilibri.um binding experiments in. aqueous solution showed that the MIP had higher＇binding capacity for nickel（ II ）-2,2＇-dipyridyl than the non-imprinted polymer with the same chemical composition. Theinfluences of metal ions and pHof solution on the recognition performance of MIP were investigated. The bindingcharacteristics of MIP were evaluated by the Scatchard analysis with one-site and two-site binding equations, respectively. The results on substrate selectivity of imprinted polymer revealed that MIP had better binding affinityfor template among thetested compounds.

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.

Study on Property of Salicylaldehyde Schiff Base Metal Complexes for Catalytic Oxidation of Model Sulfides

Seven kinds of Schiff base metal complexes(C1-C7)were synthesized by the reaction of substituted salicylaldehyde Schiff base with cobalt nitrate,nickel nitrate,and copper nitrate,respectively.The oxygen carrying performance,and the catalytic property of complexes for the oxidation of model sulfides 1-hexanethiol,dibutyl sulfide,and 2-methylthiophene along with their influencing factors were explored,while the oxidized products of the model sulfides were also analyzed and characterized.The results show that the catalytic oxidation property of the complexes is determined by their oxygen carrying performance and solubility in n-octane.The oxygen carrying performance of the complexes is mainly affected by the central ion species,the electronic effects,and the spatial effects of the substituents as well as the degree of conjugation.More specifically,the oxygen carrying performance can be improved by enhancing the oxygenation capacity of the central metal ions,increasing the electron donating ability of the ligand substituent,and diminishing the steric hindrance as well as extending the conjugated chain.Complexes C7 were found to be with high oxygen carrying capacity and high solubility in n-octane,which shows the best catalytic oxidation property,and the oxidation conversion rates for 1-hexylthiol,dibutyl sulfide,and 2-methylthiophene are 74.2%,65.1%,and 22.7%,respectively.Upon using the oxidation catalyst of Schiff base metal complexes,three sulfides can be oxidized by oxygen to form sulfones and sulfoxides.1-Hexanethiol and dibutyl sulfide will continue to be oxidized to form sulfates and sulfites.

RANDOM COPOLYMER OF PROPYLENE OXIDE AND ETHYLENE OXIDE PREPARED BY DOUBLE METAL CYANIDE COMPLEX CATALYST

Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H-1-NMR analysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecular weight copolymers with various EO content were obtained and their values of molecular weight distribution (MWD) fell in the range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used, The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.

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.

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 and Spectroscopic Characteriration of Transition MetalComplexes of Maleionitriledithiolene and 1,10-Phenanthroline

The title complex M (mnt) (phen), M=Fe11, Co11. Ni11, Cu11. Zn11. was respectivelysynthesized by reaction of disodium maleionitriledithiolate (Na2 (mnt) ) with corresponding metalcomplex M (phen) Cl2. Charge transfer transitions in the absorption and emission spectra have beenstuded.

Infrared Spectra,Structures and Bonding of Binuclear Transition Metal Carbonyl Cluster Ions

Binuclear transition metal carbonyl clusters serve as the simplest models in understand- ing metal-metal and ligand bonding that are important organometallic chemistry catalysis. Binuclear first row transition metal carbonyl ions are produced via a pulsed laser vaporiza- tion/supersonic expansion cluster ion source in the gas phase. These ions are studied by mass-selected infrared photodissociation spectroscopy in the carbonyl stretching frequency region. Density functional theory calculations have been performed on the geometric struc- tures and vibrational spectra of the carbonyl ions. Their geometric and electronic structures are determined by comparison of the experimental IR spectra with the simulated spectra. The structure and the metM-metal and metal-CO bonding of both saturated and unsaturated homonuclear as well as heteronuclear carbonyl cluster cations and anions are discussed.