20350-26-9Relevant articles and documents
Dinuclear metal(II)-acetato complexes based on bicompartmental 4-chlorophenolate: Syntheses, structures, magnetic properties, DNA interactions and phosphodiester hydrolysis
Massoud, Salah S.,Ledet, Catherine C.,Junk, Thomas,Bosch, Simone,Comba, Peter,Herchel, Radovan,Ho?ek, Jan,Trávní?ek, Zdeněk,Fischer, Roland C.,Mautner, Franz A.
, p. 12933 - 12950 (2016)
A series of dinuclear metal(ii)-acetato complexes: [Ni2(μ-LClO)(μ2-OAc)2](PF6)·3H2O (1), [Ni2(μ-LClO)(μ2-OAc)2](ClO4)·CH3COCH3 (2), [Cu2(μ-LClO)(μ2-OAc)(ClO4)](ClO4) (3), [Cu2(μ-LClO)(OAc)2](PF6)·H2O (4), [Zn2(μ-LClO)(μ2-OAc)2](PF6) (5) and [Mn2(LCl-O)(μ2-OAc)2](ClO4)·H2O (6), where LClO- = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-chlorophenolate, were synthesized. The complexes were structurally characterized by spectroscopic techniques and single crystal X-ray crystallography. Six-coordinate geometries with doubly bridged acetato ligands were found in Ni(ii), Zn(ii) and Mn(ii) complexes 1, 2, 5 and 6, whereas with Cu(ii) complexes a five-coordinate species was obtained with 4, and mixed five- and six-coordinate geometries with a doubly bridged dimetal core were observed in 3. The magnetic properties of complexes 1-4 and 6 were studied at variable temperatures and revealed weak to very weak antiferromagnetic interactions in 1, 2, 4 and 6 (J = -0.55 to -9.4 cm-1) and ferromagnetic coupling in 3 (J = 15.4 cm-1). These results are consistent with DFT calculations performed at the B3LYP/def2-TZVP(-f) level of theory. Under physiological conditions, the interaction of the dinculear complexes 1-5 with supercoiled plasmid ds-DNA did not show any pronounced nuclease activity, but Ni(ii) complexes 1 and 2 revealed a strong ability to unwind the supercoiled conformation of ds-DNA. The mechanistic studies performed on the interaction of the Ni(ii) complexes with DNA demonstrated the important impact of the nickel(ii) ion in the unwinding process. In combination with the DNA study, the phosphatase activity of complexes 1, 3, and 5 was examined by the phosphodiester hydrolysis of bis(2,4-dinitrophenol)phosphate (BDNPP) in the pH range of 5.5-10.5 at 25 °C. The Michaelis-Menten kinetics performed at pH 7 and 10.7 showed that catalytic efficiencies kcat/KM (kcat = catalytic rate constant, KM = substrate binding constant) decrease in the order: Ni(ii), 1 > Zn(ii), 5 > Cu(ii), 3. A similar trend was also observed with the turnover numbers at pH = 7. The results are discussed in relation to the coordination geometry and nature of the metal center as well as the steric environment imposed by the compartmental phenoxido ligand.
The crystal structure, self-assembly, DNA-binding and cleavage studies of the [2]pseudorotaxane composed of cucurbit[6]uril
Huo, Fang-Jun,Yin, Cai-Xia,Yang, Pin
, p. 932 - 936 (2007)
The [2]pseudorotaxanes of cucurbit[6]uril with guest molecule 1,6-bis(imidazol-1-yl)hexane (BIMH) were synthesized and characterized by ESI-MS spectrometry, 1H NMR spectra, and X-ray diffraction crystallography. The influence of different anion
Asymmetric mono- and dinuclear GaIII and ZnII complexes as models for purple acid phosphatases
Bosch, Simone,Comba, Peter,Gahan, Lawrence R.,Schenk, Gerhard
, p. 343 - 355 (2016)
Derivatives of the known dinucleating ligands HL1 (2,6-bis{[bis(pyridin-2-ylmethyl)amino]methyl}-4-methylphenol) and H2L2 (2-{[bis(pyridin-2-ylmethyl)amino]methyl}-6-{[(2-hydroxybenzyl)(pyridine-2-ylmethyl)amino]methyl}-4-methylphenol) with two pivaloylamido hydrogen bond donor substituents, H3L3 and H3L5, have been prepared. The mono-, homo- and heterodinuclear ZnII and GaIII complexes of these ligands have been prepared and characterized. The solution equilibria are discussed on the basis of extensive NMR spectroscopic, mass spectrometric and pH-dependent UV–vis spectroscopic titrations. The phosphoester hydrolysis activity of the complexes has been studied as a function of pH and substrate concentration and analyzed using Michaelis–Menten kinetics. It emerges that the mixed metal (mixed valent) complex of the ligand with an asymmetric disposition of the hydrogen bonding substituents (H3L3) is a functional model for the mixed valent, dinuclear metallohydrolase purple acid phosphatase. This complex combines the essential structural features of the active site of PAP and is the first heterodinuclear model complex mimicking the essential function of PAPs, i.e. the hydrolysis of phosphomonoesters.
Second-coordination-sphere effects increase the catalytic efficiency of an extended model for FeIIIMII purple acid phosphatases
De Souza, Bernardo,Kreft, Gabriel L.,Bortolotto, Tiago,Terenzi, Hernan,Bortoluzzi, Adailton J.,Castellano, Eduardo E.,Peralta, Rosely A.,Domingos, Josiel B.,Neves, Ademir
, p. 3594 - 3596 (2013)
Herein we describe the synthesis of a new heterodinuclear Fe IIICuII model complex for the active site of purple acid phosphatases and its binding to a polyamine chain, a model for the amino acid residues around the active site. The properties of these systems and their catalytic activity in the hydrolysis of bis(2,4-dinitrophenyl)phosphate are compared, and conclusions regarding the effects of the second coordination sphere are drawn. The positive effect of the polymeric chain on DNA hydrolysis is also described and discussed.
Mechanism of reaction of hydroxide ion with dinitrochlorobenzenes
Bacaloglu, Radu,Blaskó, Andrei,Bunton, Clifford,Dorwin, Ellen,Ortega, Francisco,Zucco, César
, p. 238 - 246 (1991)
Formation of dinitrophenoxide ion from 2,4- and 2,6-dinitrochlorobenzene (2,4- and 2,6-DNCB) and OH- (OD-) in 70:30 and 80:20 (v/v) DMSO-H2O (D2O) is accompanied by extensive 1H NMR line broadening of unreacted substrate and exchange of arene hydrogen with D2O, which is quantitative at the 3-position of 2,4-DNCB. Unproductive Meisenheimer complexes are detected spectrophotometrically in the course of reaction. For reaction of 2,4-DNCB, the Meisenheimer 3-complex is formed first and then the more stable 5-complex can be detected and characterized by NMR spectrometry. There is no hydrogen exchange of Meisenheimer complexes or dinitrophenoxide ions and their 1H NMR signals are not broadened. These results do not fit the classical mechanism of single-step nucleophilic addition, but they, and the kinetic results, are fitted by a reaction scheme involving single-electron transfer from OH- to give a charge-transfer complex of OH? and a radical anion which collapses to give Meisenheimer complexes and aryl oxide ion. This scheme is consistent with MO calculations by the AM1 method.
Nonlinear Broensted-Type Plot in the Pyridinolysis of 2,4-Dinitrophenyl Benzoate in Aqueous Ethanol
Castro, Enrique A.,Santander, Carlos R.
, p. 3595 - 3600 (1985)
From the kinetics of the title reaction in 44 wtpercent aqueous ethanol at 25 deg C, ionic strength 0,2 M (KCl), a curved Broensted-type plot is obtained.The curve is interpreted in terms of a zwitterionic tetrahedral intermediate in the reaction path and a change in the rate-determining step from breakdown to products of this intermediate to its formation as the pyridine becomes more basic.A semiempirical equation based on this hypothesis accounts for the experimental results.The center of the Broensted-type curvature (pKa0) is located at pKa = 9.5, lower than the value found in the pyridinolysis of 2,4-dinitrophenyl p-nitrobenzoate in the same solvent, showing that electron withdrawal from the acyl group of the substrate favors amine expulsion relative to phenoxide from the tetrahedral intermediate.It is claimed that the influence of the acyl group of the substrate on the value of pKa0 cannot be quantified when comparing similar reactions in water and aqueous ethanol since the pKa0 value for a given reaction should be larger in the latter solvent.The activation parameters obtained support the hypothesis that for the title reactions, pKa0 > 9.
Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: Differential medium effect determines reactivity and reaction mechanism
Um, Ik-Hwan,Bae, Ae-Ri,Dust, Julian M.
, p. 13 - 19 (2019/01/10)
A kinetic study on nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted-cinnamates (1a-1f) and Y-substituted-phenyl cinnamates (2a-2g) with a series of alicyclic secondary amines in MeCN at 25.0 ± 0.1 °C is reported. The Br?nsted-type pl
