Thermally initiated frontal polymerization of transition metal nitrate acrylamide complexes

The effect of the thermally initiated frontal polymerization of acrylamide complexes of transition metal nitrates such as those of Mn(II), Co(II), Ni(II), and Zn(II) was disclosed. The rate of the polymerization front propagation was found to be 2?9 × 10^?2cm/c, depending appreciably on sample diameter and density, as well as the presence of radical inhibitor additives. The rate was found to decrease in the series: Co(II) > Ni(II) > Mn(II) > Zn(II). Polymerization was shown to occur directly in the melting region of a complex at 80–100°C to give three-dimensional polymers. A mechanism of the polymerization being initiated with the products of the partial nitrate group decomposition was proposed. © 1994 John Wiley & Sons, Inc.     

Thermal polymerization of acrylamide during the formation of the structures of acrylamide complexes with metal nitrates

The effects of the composition of Mn^II, Co^II or Ni^II nitrate hydrate — acrylamide (AAM) mixtures and of the duration of their aging at ambient temperature on the structurization of acrylamide complexes and on the character of their thermal polymerization have been studied by scanning and isothermic differential calorimetry. Structurization is a rather prolonged step in the synthesis of acrylamide complexes. The peculiarities and rate of this step are determined by the composition of the mixture and by the nature of the complexforming compound; it yields several structural modifications of the AAM complexes. The thermal polymerization of those structural forms of acrylamide complexes that polymerize at low temperatures may be formally described as polymerization in an acrylamide-nitrate-water mixture. The effective activation energy of the polymerization of acrylamide mixed with Mn^II nitrate hydrate is 45 kJ mol^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 679–683, April, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research, Project No. 93-03-4162.     

The transition of spontaneous polymerization of acrylamide to “explosive” regime

Experimental results related to the transition of spontaneous polymerization of acrylamide complexes with metal nitrates to the “explosive” regime at room temperature are presented. It is suggested that the “explosion” has a thermal nature. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 859–861, April, 1997.     

Calorimetric study of polymerizing complexes of acrylamide with cobalt(ii) nitrate

Thermal polymerization of complexes of acrylamide with Co^II nitrate has been investigated by differential scanning calorimetry. The conditions of the synthesis of the samples and their treatment have been found to affect the thermal and polymerization properties of the complexes. The existence of several structural modifications of the complex differing noticeably in their polymerization ability has been revealed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1414–1417, August, 1993.     

Tuning luminescent properties of a metal organic framework by insertion of metal complexes

Abstract

We report the preparation and characterisation of new emissive materials based on the insertion of platinum(II) and iridium(III) complexes inside the Al(OH)(bipyridine dicarboxylate) metal organic framework (MOF-253). Guest incorporation is performed by coordination of a metal complex precursor, and provides increased robustness to the system compared to guest inclusion by its physical diffusion. Powder X-ray diffraction analysis highlights the high degree of crystallinity of the materials, with a complete change in the lattice parameters upon metal complex insertion. The photophysical properties of the resulting materials were thoroughly investigated. This synthetic approach is particularly attractive since, as we show, it is possible to tune the emission maxima of our materials over the entire visible range.     

Pyridine-type complexes of transition metal halides

Formation of nitrogen ligated complexes of types NiL₆X₂, NiL₄X₂, NiL₂X₂ and NiL₁X₂ (whereL=pyridine, 2-, 3- and 4-methyl-pyridine andX=F, Cl, Br, I) have been studied by traditional preparative methods, i.e. from solutions and by solid-gas phase chemisorption. Quaternary mixed complexes were obtained by chemisorption from heated intermediates. The complexes thus formed were further analysed by simultaneous TG-DTG-DTA. Effects of the ligands on stoichiometry and thermal properties of the complexes are discussed.     

Thermodynamic properties and solution equilibria of aqueous bivalent transition metal nitrates and magnesium nitrate

Osmotic coefficients for Mn(NO₃)₂, Co(NO₃)₂, Ni(NO₃)₂, Cu(NO₃)₂, Zn(NO₃)₂, and Mg(NO₃)₂ in aqueous solution have been determined by the isopiestic method at 25°C, and activity coefficients have been derived. The results agree with the literature data for Zn(NO₃)₂, while they are significantly different for Co(NO₃)₂, Cu(NO₃)₂, and Mg(NO₃)₂, and those for Mn(NO₃)₂ and Ni(NO₃)₂ are new. The concentration dependence of the osmotic coefficients for the bivalent metal nitrates is similar to that for the trifluoroacetates, while it differs from those for the other salts of the same series of metals. The results are discussed in terms of the inner-sphere and outer-sphere association of ions, auxiliary information being derived from the concentration effects in the visible spectra of the coloured metal nitrates.     

Synthesis and properties of a temperature-sensitive chelating hydrogel and its metal complexes

A temperature-sensitive chelating hydrogel was synthesized by the copolymerization of 1-(β-acrylamidoethyl)-3-hydroxy-2-methyl-4(1H)-pyridinone (AHMP) and N-isopropylacrylamide (NIPAA) in the presence of N,N' -ethylene-bis-acrylamide as a crosslinking agent. The AHMP-NIPAA hydrogel formed a red complex with iron(III) and a pale green complex with Cu(II), respectively. It was observed that the hydrogel and its metal complexes had a high swelling ratio below the temperature of 35°C, while above that temperature the swelling ratios were dramatically decreased. Furthermore, the swelling ratio of the metal complexes was much lower at the swelling temperature (below 35°C) than that of the hydrogel itself, which might be due to the lower flexibility of the complexes. The iron(III) chelating study showed that the hydrogel had a high chelating efficiency at its swelling temperature, while the chelating efficiency of the hydrogel was very low at its deswelling temperature (>35°C). It was found that the chelating efficiency depended on the swelling ratio of the hydrogel in water, which could be explained by the difference in contactable internal surfaces at different temperatures. The hydrogel and its metal complexes could be easily separated at their deswelling temperature. It was also convenient to regenerate the hydrogel with 1 M HCl for reuse.     

Correlation between the reactivity and the structural and thermal properties of supported metal nitrates

Montmorillonite-supported iron(III) nitrate and copper(II) nitrate reagents, and other supported metal nitrates prepared in the same way, were investigated by thermal and X-ray powder diffraction methods. The metal nitrates are present on the support in the form of crystalline hydrate and not as acetone solvate as supposed earlier. Thermal decomposition of metal nitrates that are active in model reactions proceeds in a different way from that of the practically inactive nitrates. In the former case, water release and nitrate decomposition itself are simultaneous process. These and other results contributed to determination of suitable reaction conditions for the montmorillonite-supported reagents.     

Metalloantibiotics: synthesis and antibacterial activity of cefepime metal complexes

Cefepime interacts with transition metal(II) ions to give [M(cefepime)Cl₂] complexes (M = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) which were characterized by physicochemical and spectroscopic methods. The complexes are insoluble in water and common organic solvents, and probably have polymeric structures. The spectra indicated that the ligand is a multidentate chelating agent. The complexes have been screened for antibacterial activity against several bacteria and showed activity less than that of free cefepime.     

Lanthanide nitrate complexes with 2-azacyclononanone

Thermal behavior of rare earth nitrate complexes with 2-azacyclononanone (AZA) with Ln(NO₃)₃·3(AZA) composition (where Ln=Gd, Er and Ho) was analyzed in kinetic point of view. Kinetic parameters were calculated from thermogravimetric data. All obtained results were similar. The first decomposition step was representative to the loss of ligand and the residue was essentially Ln₂O₃. Furthermore, a reaction path was proposed for the thermal decomposition of the Ln(NO₃)₃·3(AZA).     

Electronic structures of multi-decker transition metal sandwich complexes

The electronic structures of multi-decker transition metal sandwich complexes are discussed according to the structure rules for transition metal heterocarboranes. A series of skeletons of the structures Fe₂C₅(D_5h), Ni₂C₅(D_5h), V₂C₆(D_6h), Co₂C₆(D_6h), and Fe₂C₄(D_4h) are calculated using the EHMO method. The calculated results show that the number of valence bonding orbitals (VBO) can vary as the distance between the metal atoms in the metalocenes is increased. This fact can be used to explain the number of valence electrons (VE) in triple-decker sandwich complexes. The conclusions are proved and discussed through a theoretical analysis of the electronic structures of such complexes and through EHMO calculations for actual compounds containing 29–34 valence electrons.     

Model investigation of the polymerization of acrylamide complexes with metal nitrates by ESR

Modelling experiments have shown that the interaction between NO₂ and acrylamide (AA) and the AA complex with calcium nitrate leads to the formation of radical centers. Analogous paramagnetic centers are detected directly in AA complexes with calcium nitrate. The ESR spectrum differs from that of -irradiated AA and is caused by nitroxyl radicals appearing in the course of the consecutive transformations in the system. The data obtained support the earlier suggested mechanism of NO₂-initiated polymerization of acrylamide complexes with metal nitrates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 534–536, March, 1994.This work was financially supported by the Russian Foundation for Basic Research (project No. 93-03-4162).     

Interaction of vinylpyridines with 1,3-dienes catalyzed by transition metal complexes

The linear and cyclic cooligomerization of 2-vinyl-, 2-methyl-5-vinyl-, and 4-vinylpyridines with 1,3-dienes and trienes catalyzed by complexes of transition metals (Fe, Co, Ni, Mn, Cr, Pd, Ru, Rh, and Zr) was carried out to give unsaturated pyridines containing alkenyl and cycloalkenyl substituents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 916–921, May, 1993.     

Polybisaminophosphazene-silver nitrate complexes: Coordination and properties

Poly[bis(propylamino)phosphazene]-silver nitrate complexes and poly[bis-(butylamino)phosphazene]-silver nitrate complexes with various salt contents, which are new polyphosphazene-salt complexes, have been prepared. The complexes were characterized by FTIR, ³¹P-NMR, and ¹³C-NMR spectroscopies, and the thermal properties were studied by DSC, TGA, and TGA/FTIR measurements. It was found that the poly[(bisamino)phosphazene]-silver coordination may occur both at the backbone nitrogen and the side chain nitrogen and incorporation of silver nitrate into the polymer lowered the decomposition temperature. The complexes can be cast as freestanding film with good dimensional stability. Compared to their parent polymers, the highest conductivities of the films are increased three to four orders in magnitude at room temperature. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1023–1031, 1997     

Preparation and reactivity of metal containing monomers

The preparation of HTSC ceramics based on Y^III and Bi^III was studied. The polymers were obtained by two methods: by the reaction of preliminarily synthesized polyacrylic acid (PAA) or polyacrylamide (PAAm) with Y^III, Ba^II, and Cu^II nitrates or by copolymerization of metal containing monomers (metal (Y^II, Ba^II, and Cu^II) acrylates or acrylamide complexes of metal (Bi^III, Ca^II, Sr^II, Pb^II, and Cu^II) nitrates). The copolymerization was carried out in solution, in the solid phase, or using spontaneous polymerization, which has been previously discovered by the authors. The properties of the HTSC ceramics obtained are improved when the products of copolymerization of metal containing monomers are used.For part 41, seeIzv. Akad. Nauk, Ser. Khim., 1995, 885 [Russ. Chem. Bull., 1995,44, 858 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1096–1101, June, 1995.The authors wish to thank V. N. Topnikov and M. K. Makova for measuring the characteristics of HTSC ceramics and V. A. Zhorin for conducting copolymerization of metal containing monomers under high pressures combined with shear strains.The work was carried out with financial support of the International Science Foundation (Grant NJB 000).     

Electrochemical synthesis and properties of δ-fluoroacyl and δ-perfluoroalkyl transition metal complexes

The electrochemical synthesis of δ-fluoroacyl complexes [M]-δ-COR_f(M=C₅H₅(CO)₃W or (CO)₅Mn; R_f=CF₃ or C₄F₉) was performed according to two procedures: (1) the preliminary electrochemical synthesis of [M]⁻ from [M]₂ followed by reaction with a fluorine-containing compound and (2) the electrochemical synthesis of [M]⁻ in the presence of a fluorine-containing compound. Trifluoroacetic anhydride was demonstrated to be the best acylating agent in these reactions. The electrochemical properties of the resulting complexes were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 373–375, February, 2000.     

Characterization and antimicrobial properties of metal complexes of polypropylene fibers grafted with acrylic acid using gamma irradiation

Polypropylene fibers were treated against microbial effects by gamma radiation‐induced grafting of acrylic acid, followed by metal complexation with Zn²⁺ or Ag⁺ metal ions. The treated polypropylene fibers were characterized by using Fourier transform infrared spectroscopy and scanning electron microscopy. The effect of the treatment on the thermal stability was investigated by using thermogravimetric analysis, in which a slight increase in the major thermal stability was observed. The antimicrobial activity of the treated fibers was also evaluated. On the basis of the obtained results, it was found that the antimicrobial properties of the treated fibers were enhanced both qualitatively, as indicated by the distinct inhibition zone diameter towards Gram‐positive as well as Gram‐negative bacterial strains under study, and quantitatively, in which 100% inhibition of Staphylococcus aureus and Escherichia coli was achieved. Copyright © 2015 John Wiley & Sons, Ltd.     

REVIEW: metal complexes as urease inhibitors

Urease plays a significant role in the pathogenesis of several diseases and also has practical implications in other fields, such as agriculture or chemical analysis. Among the multitude of chemical species known to inhibit urease, metal complexes stand out as a special category due to their specific mechanism of action, distinct from purely organic substances. Their inhibitory activity seems to depend on the type of metal and its oxidation state as well as on the coordination environment of the central atom. Furthermore, the study of the interaction between metal ions and their complexes with urease renders valuable insights into detailed catalytic mechanisms of this enzyme. This brief survey attempts to provide an overview of the published research on urease inhibition by metal complexes.     

A calorimetric study of spontaneous polymerization in acrylamide systems containing metal nitrates

A calorimetric study of the kinetics of spontaneous polymerization of acrylamide in systems containing Cr(III) and Er(III) nitrates has been carried out. At 20–25 °C, the process is characterized by a considerable induction period (20–40 min), a fast increase of the polymerization rate, up to its maximum value (5–10 min), and its subsequent slow decrease to insignificant values. It has been established that the composition of the reaction mixture significantly affects the recorded polymerization rates, and practically does not change the time parameters and the integral degrees of conversion of the process, which are 20 and 80 % for the nitrates of Cr(III) and Er(III), respectively. The effect of the addition of water or inhibitors of radical reactions on the process has been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1070–1074, June, 1993.