scholarly journals Biomimetic Water Oxidation Catalyzed by a Binuclear Ruthenium (IV) Nitrido-Chloride Complex with Lithium Counter-Cations

Biomimetics ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 3
Author(s):  
Zinaida M. Dzhabieva ◽  
Gennady V. Shilov ◽  
Lidia V. Avdeeva ◽  
Vladislav V. Dobrygin ◽  
Virineya Yu. Tkachenko ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Lithium Salt ◽  
Uv Spectroscopy ◽  
Chloride Complex ◽  
Spectrometric Analysis ◽  
Water Molecules ◽  
Acidic Solutions ◽  
Binuclear Structure ◽  
Dimerization Product ◽  
Coordinated Water

The lithium salt of the binuclear nitrido complex of ruthenium (IV) Li3(Ru2NCl8·2H2O) was synthesized. Using UV spectroscopy and voltammetry, we studied complex behavior in aqueous solutions. It was found that in dilute solutions of this compound, Cl− ions are replaced by H2O molecules, and the intra-sphere redox reaction between Ru (IV) and H2O, as well as the oxidation of water with the formation of oxygen and the acidic dissociation of coordinated water molecules also have been taking place. It was established by IR spectroscopy and ESI mass spectrometric analysis that not only the binuclear structure of the complex is preserved in acidic solutions, but also its dimerization product into the tetra-ruthenium dinitrido cluster Ru4N2O5+, which is a catalyst for the water oxidation reaction. The activity of the catalyst was TOF = 0.33 s−1, TON = 304.

A gadolinium cryptate with two coordinated water molecules

1998 ◽  
pp. 3711-3714 ◽  
Author(s):  
S. W. Annie Bligh ◽  
Michael G. B. Drew ◽  
Noreen Martin ◽  
Beatrice Maubert ◽  
Jane Nelson
Keyword(s):  
Water Molecules ◽  
Coordinated Water

scholarly journals Entropy-driven binding of gut bacterial β-glucuronidase inhibitors ameliorates irinotecan-induced toxicity

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Hsien-Ya Lin ◽  
Chia-Yu Chen ◽  
Ting-Chien Lin ◽  
Lun-Fu Yeh ◽  
Wei-Che Hsieh ◽  
...  
Keyword(s):  
Cancer Metabolism ◽  
Glucuronic Acid ◽  
Intestinal Epithelial Cells ◽  
Primary Treatment ◽  
Water Molecules ◽  
Intestinal Epithelial ◽  
E Coli ◽  
Severe Diarrhea ◽  
Coordinated Water ◽  
Consequent Increase

AbstractIrinotecan inhibits cell proliferation and thus is used for the primary treatment of colorectal cancer. Metabolism of irinotecan involves incorporation of β-glucuronic acid to facilitate excretion. During transit of the glucuronidated product through the gastrointestinal tract, an induced upregulation of gut microbial β-glucuronidase (GUS) activity may cause severe diarrhea and thus force many patients to stop treatment. We herein report the development of uronic isofagomine (UIFG) derivatives that act as general, potent inhibitors of bacterial GUSs, especially those of Escherichia coli and Clostridium perfringens. The best inhibitor, C6-nonyl UIFG, is 23,300-fold more selective for E. coli GUS than for human GUS (Ki = 0.0045 and 105 μM, respectively). Structural evidence indicated that the loss of coordinated water molecules, with the consequent increase in entropy, contributes to the high affinity and selectivity for bacterial GUSs. The inhibitors also effectively reduced irinotecan-induced diarrhea in mice without damaging intestinal epithelial cells.

scholarly journals Electrocatalysis of the HER in acid and alkaline media

2013 ◽  
Vol 78 (12) ◽  
pp. 2007-2015 ◽  
Author(s):  
Nemanja Danilovic ◽  
Ram Subbaraman ◽  
Dusan Strmcnik ◽  
Vojislav Stamenkovic ◽  
Nenad Markovic
Keyword(s):  
Catalytic Decomposition ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Water Molecules ◽  
Bifunctional Catalysts ◽  
High Coverage ◽  
Acidic Solutions ◽  
Noble Metal Catalysts ◽  
Alkaline Environments ◽  
Decomposition Of Water

Trends in the HER are studied on selected metals (M= Cu, Ag, Au, Pt, Ru, Ir, Ti) in acid and alkaline environments. We found that with the exception of Pt, Ir and Au, due to high coverage by spectator species on non-noble metal catalysts, experimentally established positions of Cu , Ag, Ru and Ti in the observed volcano relations are still uncertain. We also found that while in acidic solutions the M-Hupd binding energy most likely is controlling the activity trends, the trends in activity in alkaline solutions are controlled by a delicate balance between two descriptors: the M-Had interaction as well as the energetics required to dissociate water molecules. The importance of the second descriptor is confirmed by introducing bifunctional catalysts such as M modified by Ni(OH); e.g. while the latter serves to enhance catalytic decomposition of water, the metal sites are required for collecting and recombining the produced hydrogen intermediates.

scholarly journals SOLVATION OF THE [Cr(NCS)4(IMIDAZOLE)2] ION IN ETHANOL-WATER MIXTURES

2002 ◽  
Vol 10 (11) ◽  
pp. 63-72
Author(s):  
lon Ganescu ◽  
George Bratulescu ◽  
Ion Papa ◽  
Anca Ganescu ◽  
Alin Barbu ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Order Reaction ◽  
Water Molecules ◽  
Hydrogen Ions ◽  
Second Order Reaction ◽  
Acidic Solutions ◽  
The Third ◽  
Competitive Reactions ◽  
Different Temperatures ◽  
Kinetics Of

Salvation kinetics of [Cr(NCS)4(imidazole)2]- has been studied in ethanol-water mixtures at different temperatures. The first stage of the solvation consists of two competitive reactions: two NCS- ions are exchanged, presumably, by water molecules and simultaneously an imidazole molecule by ethanol, the latter in a second-order reaction, accelerated by hydrogen ions. The exchange of the amine is followed by the substitution of the first two NCS- ions. The third and fourth NCS- ions are substituted only in neutral and slightly acidic solutions. Kinetic parameters have been determined for reactions (1), (2), and (4). The influence of the solvent composition and acidity is discussed

scholarly journals Crystal structure of poly[diaquabis(μ5-benzene-1,3-dicarboxylato)(N,N-dimethylformamide)cadmium(II)disodium(I)]

2017 ◽  
Vol 73 (11) ◽  
pp. 1599-1602 ◽  
Author(s):  
Matimon Sangsawang ◽  
Kittipong Chainok ◽  
Nanthawat Wannarit
Keyword(s):  
Crystal Structure ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Carboxylate Groups ◽  
Benzene Rings ◽  
Coordinated Water ◽  
Coordinate Geometry

The title compound, [CdNa2(C8H4O4)2(C3H7NO)(H2O)2]nor [CdNa2(1,3-bdc)2(DMF)(H2O)2]n, is a new CdII–NaIheterobimetallic coordination polymer. The asymmetric unit consists of one CdIIatom, two NaIatoms, two 1,3-bdc ligands, two coordinated water molecules and one coordinated DMF molecule. The CdIIatom exhibits a seven-coordinate geometry, while the NaIatoms can be considered to be pentacoordinate. The metal ions and their symmetry-related equivalents are connectedviachelating–bridging carboxylate groups of the 1,3-bdc ligands to generate a three-dimensional framework. In the crystal, there are classical O—H...O hydrogen bonds involving the coordinated water molecules and the 1,3-bdc carboxylate groups and π–π stacking between the benzene rings of the 1,3-bdc ligands present within the frameworks.

scholarly journals Crystal structure ofcatena-poly[[[tetraaquairon(II)]-trans-μ-1,2-bis(pyridin-4-yl)ethene-κ2N:N′] bis(p-toluenesulfonate) methanol disolvate]

2017 ◽  
Vol 73 (12) ◽  
pp. 1977-1980
Author(s):  
Volodymyr M. Hiiuk ◽  
Diana D. Barakhty ◽  
Sergiu Shova ◽  
Ruslan A. Polunin ◽  
Il'ya A. Gural'skiy
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Distorted Octahedral Geometry ◽  
Water Molecules ◽  
Supramolecular Network ◽  
Polymeric Complex ◽  
Distorted Octahedral ◽  
Polymeric Chains ◽  
Coordinated Water

In the title polymeric complex, {[Fe(C12H10N2)2(H2O)4](CH3C6H4SO3)2·2CH3OH}n, the FeIIcation, located on an inversion centre, is coordinated by four water molecules in the equatorial positions and two 1,2-bis(pyridin-4-yl)ethene molecules in the axial positions. This results in a distorted octahedral geometry for the [N2O4] coordination polyhedron. The 1,2-bis(pyridin-4-yl)ethene molecules bridge the FeIIcations, forming polymeric chains running along thea-axis direction. Stabilization of the crystal structure is provided by O—H...O hydrogen bonds; these are formed by coordinated water molecules as donors towards the O atoms of the methanol molecules and tosylate anions as acceptors of protons, leading to the formation of a three-dimensional supramolecular network. Weak C—H...O hydrogen bonds are also observed in the crystal.

scholarly journals Crystal structure of a nickel compound comprising two nickel(II) complexes with different ligand environments: [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2

2020 ◽  
Vol 76 (3) ◽  
pp. 314-317
Author(s):  
Karilys González Nieves ◽  
Dalice M. Piñero Cruz
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Molar Ratio ◽  
Water Molecules ◽  
Nickel Compound ◽  
Counter Anion ◽  
Cationic Complex ◽  
Coordinated Water ◽  
Co Precipitation ◽  
Metal Ligand

The title compound, diaqua[tris(2-aminoethyl)amine]nickel(II) hexaaquanickel(II) bis(sulfate), [Ni(C6H18N4)(H2O)2][Ni(H2O)6](SO4)2 or [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2, consists of two octahedral nickel complexes within the same unit cell. These metal complexes are formed from the reaction of [Ni(H2O)6](SO4) and the ligand tris(2-aminoethyl)amine (tren). The crystals of the title compound are purple, different from those of the starting complex [Ni(H2O)6](SO4), which are turquoise. The reaction was performed both in a 1:1 and 1:2 metal–ligand molar ratio, always yielding the co-precipitation of the two types of crystals. The asymmetric unit of the title compound, which crystallizes in the space group Pnma, consists of two half NiII complexes and a sulfate counter-anion. The mononuclear cationic complex [Ni(tren)(H2O)2]2+ comprises an Ni ion, the tren ligand and two water molecules, while the mononuclear complex [Ni(H2O)6]2+ consists of another Ni ion surrounded by six coordinated water molecules. The [Ni(tren)(H2O)2] and [Ni(H2O)6] subunits are connected to the SO4 2− counter-anions through hydrogen bonding, thus consolidating the crystal structure.

scholarly journals Synthesis, Single Crystal Structural Investigation, Hirshfeld Surface Analysis, Thermoanalysis and Spectroscopic Study of Two New Cu(II) and Co(II) Transition-Metal Complexes

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 986
Author(s):  
Rim Boubakri ◽  
Mirosław Szybowicz ◽  
Mariola Sadej ◽  
Sarra Soudani ◽  
Frédéric Lefebvre ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Organic Ligand ◽  
Free Water ◽  
Pyrimidine Ring ◽  
Water Molecules ◽  
Absorption Bands ◽  
Infrared And Raman Spectroscopy ◽  
Homo And Lumo ◽  
Coordinated Water

Two new complexes, [Cu(dimpyr)2(H2O)2](NO3)2.2H2O (1) and (Hamdimpy)2[CoCl4].H2O (2), with the monodentate ligand 2-amino-6-methylpyrimidin-4-(1H)-one (dimpyr) and the countercation 4-amino-2,6-dimetylpyrimidium (Hamdimpy), respectively, were prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. In (1), the Cu(II) cation is tetracoordinated, in a square plan fashion, by two nitrogen atoms from the pyrimidine ring of the organic ligand and two oxygen atoms of two coordinated water molecules. In the atomic arrangement, the CuO2N2 square planes are interconnected via the formation of O-H…O hydrogen bonds involving both coordinated and free water molecules and NO3− nitrate anions to form inorganic layers parallel to the (a, b) plane at z = (2n + 1)/4. In (2), the central atom Co(II) is four-coordinated in a distorted tetrahedral fashion by four Cl− ions. The [CoCl4]2− tetrahedra are arranged parallel to the plane (110) at x = (2n + 1)/2 and the organic cations are grafted between them by establishing with them hydrogen bonds of CH…Cl and NH…Cl types. The vibrational absorption bands were identified by infrared and Raman spectroscopy. Intermolecular interactions were investigated via Hirshfeld surfaces and electronic properties such as HOMO and LUMO energies were derived. The two compounds were characterized by thermal analysis to determine their thermal behavior with respect to temperature.

scholarly journals Crystal structure of poly[[di-μ3-acetato-tetraaquabis(μ2-cyclohexane-1,4-dicarboxylato)dilanthanum(III)] dihydrate]

2017 ◽  
Vol 73 (12) ◽  
pp. 1926-1930
Author(s):  
R. Drisya ◽  
U. S. Soumya Mol ◽  
P. R. Satheesh Chandran ◽  
M. Sithambaresan ◽  
M. R. Sudarsankumar
Keyword(s):  
Crystal Structure ◽  
Coordination Mode ◽  
Three Dimensional ◽  
Raw Material ◽  
Water Molecules ◽  
Supramolecular Network ◽  
Formula Unit ◽  
Remarkable Feature ◽  
Two Component ◽  
Coordinated Water

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O}nor [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, whereacis acetate and 1,4-chdc is cyclohexane-1,4-dicarboxylate anion, is a binuclear lanthanum(III) complex. Each metal atom is decacoordinated by four O atoms from two distinct 1,4-chdc2−ligands, four O atoms from three acetate groups and two O atoms from coordinated water molecules to form a distorted bicapped square-antiprismatic geometry. Two non-coordinated water molecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a onlycisconformation for cyclohexane-1,4-dicarboxylic acid, although the raw material consists of a mixture ofcisandtransisomers. The μ3-η2:η2coordination mode of the bridging acetate group and the flexible dicarboxylate fragments of 1,4-chdc2−results in the formation of infinite two-dimensional lanthanide–carboxylate layers within the crystal structure. The directionality of strong intermolecular O—H...O and weak C—H...O interactions provides robustness to the layers, which leads to the construction of a three-dimensional supramolecular network. The crystal studied was refined as a two-component twin.

Synthesis, crystal structure, and quantum mechanical studies regarding a new metal–organic complex based on Cd (II)

2021 ◽  
Author(s):  
zohreh razmara ◽  
Fereshteh Shiri ◽  
Pouya Karimi ◽  
Marek Necas
Keyword(s):  
Three Dimensional ◽  
Pentagonal Bipyramid ◽  
Quantum Mechanical ◽  
Water Molecules ◽  
Organic Complex ◽  
Polymeric Networks ◽  
Metal Organic Complex ◽  
Metal Organic ◽  
Coordinated Water ◽  
Mechanical Studies

Abstract A novel metal-organic complex formulated as [Cd (phen)(dipic) (H2O)2]. 3 H2O (phen = 1, 10-phenanthroline; dipic2−= pyridine-2,6-dicarboxylate) has been hydrothermally synthesized at 150°C for 48h. The structure of Cd complex was characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and single-crystal X-ray diffraction (SC-XRD). The crystal system of Cd complex is monoclinic with space group C 2/c. The pentagonal bipyramid (seven coordinate) around Cd2+ center filled by two terminal water ligands, one 1,10-phenanthroline, and one pyridine-2,6-dicarboxylate anion. Extensive O–H···O hydrogen bonding interactions involving all coordinated water molecules, dipicolinate oxygens, and crystallization water molecules further stabilize the complex units by linking them to form three-dimensional polymeric networks. Indeed, quantum mechanical studies were performed to understand effective factors on stability of the Cd(II) complex.

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