[MnM(egta)]. 8H<sub>2</sub> = (M = Mn, Cd): Verbindungen mit einem neuartigen zweidimensionalen magnetischen Gitter

Borrás-Almenar, J.J.; Coronado, Eugenio; Gómez‐García, Carlos J.; Ouahab, Lahcène

doi:10.1002/ange.19931050442

Cited by 3 publications

(1 citation statement)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cerium is among the most abundant rare-earth elements , and has found extensive uses in materials chemistry, , catalysis, and synthetic organic chemistry. , In catalysis, the application of cerium compounds, particularly Ce IV , has been motivated either by its prominent redox properties ( E° Ce IV /Ce III ≈ +1.44 V vs NHE) ,, or its pronounced Lewis acidity. ,, With regard to reactions performed in water, which are highly relevant for bioinorganic applications such as dephosphorylation and peptide bond hydrolysis reactions, the use of simple Ce IV salts as catalysts has been largely limited to acidic media, as in neutral and alkaline pH conditions the formation of insoluble hydroxide gels drastically limits their reactivity. , This tendency to form insoluble gels can be circumvented by complexing the Ce IV cation to ligands such as polyoxometalates (POMs). POMs are a large and diverse group of early-transition-metal–oxygen anionic clusters with unique chemical and physical properties, − and imbedding Ce IV in POMs results in rather robust, selective, and homogeneous catalysts with a wide range of applications. − …”

Section: Introductionmentioning

confidence: 99%

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

et al. 2020

View full text Add to dashboard Cite

Redox reactions between polyoxometalates (POMs) and biologically relevant molecules have been virtually unexplored but are important, considering the growing interest in the biological applications of POMs. In this work we give a detailed account on the redox behavior of CeIV-substituted polyoxometalates (CeIV-POMs) toward a range of amino acids and peptides. CeIV-POMs have been shown to act as artificial proteases that promote the selective hydrolysis of peptide bonds. In presence of a protein, a concomitant reduction of CeIV to CeIII ion is frequently observed, leading us to examine the origins of this redox reaction by first using amino acid building blocks as simple models. Among all of the examined amino acids, cysteine (Cys) showed the highest activity in reducing CeIV-POMs to CeIII-POMs, followed by the aromatic amino acids tryptophan (Trp), tyrosine (Tyr), histidine (His), and phenylalanine (Phe). While the redox reaction with Cys afforded the well-defined product cystine, no oxidation products were detected for the Trp, His, Tyr, and Phe amino acids after their reaction with CeIV-POMs, suggesting a radical pathway in which the solvent likely regenerates the amino acid. In general, the rate of redox reactions increased upon increasing the pD, temperature, and ionic strength of the reaction. Moreover, the redox reaction is highly sensitive to the type of polyoxometalate scaffold, as complexation of CeIV to a Keggin (K) or Wells–Dawson (WD) polyoxotungstate anion resulted in a large difference in the rate of redox reaction for both Cys and aromatic amino acids. The reduction of CeIVK was at least 1 order of magnitude faster in comparison to CeIVWD, in accordance with the higher redox potential of CeIVK in comparison to CeIVWD. The reaction of CeIVPOMs with a range of peptides containing redox-active amino acids revealed that the redox reaction is influenced by their coordination mode with CeIV ion, but in all examined peptides the redox reaction is favored in comparison to the hydrolytic cleavage of the peptide bond.

show abstract

Section: Introductionmentioning

confidence: 99%

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

et al. 2020

View full text Add to dashboard Cite

show abstract

Singlyanti-anti Carboxylate-Bridged Zig-Zag Chain Complexes from a Carboxylate-Containing Tridentate Schiff Base Ligand and M(hfac)2 [M = MnII, NiII, and CuII]: Synthesis, Crystal Structure, and Magnetic Properties

Colacio¹,

Domínguez‐Vera

Ghazi

et al. 1999

Eur. J. Inorg. Chem.

150

View full text Add to dashboard Cite

The reaction of M(hfac)2 with the tridentate Schiff base H2L (where H2L stands for the 1:1 condensation product of 2‐imidazolecarboxaldehyde with β‐alanine) leads to the complexes [M(HL)(hfac)]n [M = MnII, NiII, and CuII; hfac = hexafluoroacetylacetonate anion] (1–3). The structures of the complexes 1 and 3 have been solved by X‐ray crystallographic methods. The structures are very similar and consist of infinite zig‐zag chains, running parallel to the b axis, in which the metal ions are bridged sequentially by anti‐anti carboxylate groups with intrachain metal–metal distances of 6.134 Å for 1 and 6.239 Å for 3. Each monodeprotonated HL ligand acts as a tridentate one to a metal(II) ion and as a monodentate one to a neighbouring metal(II) centre. Metal atoms exhibit distorted octahedral coordination spheres comprised of two oxygen atoms from the hexafluoroacetylacetonate ligand, three donor atoms from the HL ligand and the oxygen atom belonging to the carboxylate group of an adjacent molecule. The complexes 1–3 have been confirmed to be isomorphous and isostructural on the basis of X‐ray powder diffraction and IR spectra. The magnetic properties of the three compounds were studied by susceptibility measurements as a function of the temperature and successfully analyzed in terms of the isotropic spin Hamiltonian for one‐dimensional infinite chain systems to give the coupling parameters J = –0.91 cm−1, g = 2.03 (1); J = –13.2 cm−1, g = 2.24 (2); and J = 0.40 cm−1, g = 2.11 (3). The magnetic behaviour for all three complexes can be satisfactorily explained in terms of the conformation of the bridge and the interaction between the d orbitals of the metal centre and the bridge.

show abstract

Transition‐Metal Complexes with the Novel Scorpionate Ligand Dihydrobis‐(tetrazolyl)borate: Synthesis and Characterization of Infinite Two‐Dimensional Metal‐Ligand Frameworks and One‐Dimensional Water Substructures

et al. 1995

View full text Add to dashboard Cite

. Single-crystal X-ray studies reveal the formation of two-dimensional rhombic grid sheets through the bridging action of the bis(tetrazoly1)borate ligands. Each metal atom is octahedrally coordinated with two tram L ligands and four H2B(CHN4)F nitrogen donors. Two additional, hydrogen-bonded water molecules occupy the rhombic openings in the compounds with M = Mn, Fe, CO, Zn, and Cd. The water of crystallization is held in place through hydrogen bonding from the water ligands and to the nitrogen atoms to give a substructure of parallel kinked water chains. Temperature-variable magnetic measurements show a Curie-Weiss behavior for the paramagnetic complexes with M = Mn, Fe, CO, and Cu.Our research is concerned with modifications of the scorpionate or poly(pyrazoly1)borate ligands 1 and 2[' 1, such that the pyrazolyl rings are replaced by 1,2,4-triazolyl or tetrazolyl rings, for example. The resulting ambidentate poly-triazolyl-and -tetrazolyl-borate anions, e. g. [HB-(C2H2N&]-(3)[2-41 and [H,B(CHN4),]-(4)r51 with their multiple bonding centers give rise to an interesting coordination chemistry and supramolecular architecture in the solid state with the formation of incorporated two-dimensional water layerd61 and linkage isomerism [7] for 3 and the formation of two-dimensional rhombic grid sheets for 4L61. The controlled synthesis of two-and three-dimensional inorganic materials with inner cavities for the catalysis of organic reactions[*] or with collective magnetic phenomena for the design of molecular based ferromagnet~[~] is receiving an increased attention"O1.In this paper we report on the synthesis of two-dimensional coordination polymers from 4 with manganese(II), iron(II), cobalt(II), copper(II), zinc(II), and cadmium(I1) cations, their magnetic porperties and the results of single crystal X-ray studies. Syntheses and Properties of ([M(HzO)2{rc-H2B(CHN,)z)tj2 H,O}, for M = Mn (5), Fe (6), CO (7), Zn (9), and Cd (lo), and of {Cu(NH3)Z{ZL-H2B(CHN4)2}2}, (8) The dihydrobis(tetrazoly1)borate anion 4 in the form of its potassium salt (11) reacts with manganese(II), cobalt(II), and cadmium(I1) chloride, iron(I1) sulfate, as well as with zinc(I1) acetate in water to form the diaquabis[pdihydrobis-(tetrazolyl)borate]metal(II) complexes 5-7, 9, 10 (eq. 1). Upon slow diffusion of solutions of the reactants the iron, cobalt, zinc and cadmium complexes together with water of crystallization are obtained as colorless (6, 9, 10) and orange (7) crystals directly from the reaction mixture in 35-57% crystal yield. The analogous manganese compound (5) is formed when the water is allowed to slowly evaporate at room temperature at normal pressure. From the resulting crystal mixture, the colorless crystals of 5 are obtained in analytically pure form upon washing with water to remove the cocrystallized unreacted starting material and potassium chloride.

show abstract

[MnM(egta)]. 8H₂ = (M = Mn, Cd): Verbindungen mit einem neuartigen zweidimensionalen magnetischen Gitter

Cited by 3 publications

References 11 publications

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

Singlyanti-anti Carboxylate-Bridged Zig-Zag Chain Complexes from a Carboxylate-Containing Tridentate Schiff Base Ligand and M(hfac)2 [M = MnII, NiII, and CuII]: Synthesis, Crystal Structure, and Magnetic Properties

Transition‐Metal Complexes with the Novel Scorpionate Ligand Dihydrobis‐(tetrazolyl)borate: Synthesis and Characterization of Infinite Two‐Dimensional Metal‐Ligand Frameworks and One‐Dimensional Water Substructures

Contact Info

Product

Resources

About

[MnM(egta)]. 8H2 = (M = Mn, Cd): Verbindungen mit einem neuartigen zweidimensionalen magnetischen Gitter

Cited by 3 publications

References 11 publications

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

Redox Activity of Ce(IV)-Substituted Polyoxometalates toward Amino Acids and Peptides

Singlyanti-anti Carboxylate-Bridged Zig-Zag Chain Complexes from a Carboxylate-Containing Tridentate Schiff Base Ligand and M(hfac)2 [M = MnII, NiII, and CuII]: Synthesis, Crystal Structure, and Magnetic Properties

Transition‐Metal Complexes with the Novel Scorpionate Ligand Dihydrobis‐(tetrazolyl)borate: Synthesis and Characterization of Infinite Two‐Dimensional Metal‐Ligand Frameworks and One‐Dimensional Water Substructures

Contact Info

Product

Resources

About

[MnM(egta)]. 8H₂ = (M = Mn, Cd): Verbindungen mit einem neuartigen zweidimensionalen magnetischen Gitter