427 research outputs found

    Bescherming van zwakkere personen, de zogenaamde 'personae miserabiles', in het familie(vermogens)recht, in het bijzonder het belang van het kind.

    Get PDF
    Het personen- en familierecht, zoals dit is neergelegd in Boek 1 BW, bevat rechtsregels voor natuurlijke personen, mensen van vlees en bloed, op het gebied van hun rechtsbevoegdheid, handelingsbevoegdheid en handelingsbekwaamheid. Uitgangspunt is dat alle mensen gelijkwaardig zijn. Dit is zo’n algemeen aanvaard en vanzelfsprekend beginsel, dat dit niet eens voorkomt in de algemene bepalingen van titel 1.1 BW, maar niettemin geldend recht is. Artikel 1:1 lid 1 BW bepaalt slechts dat allen die zich in Nederland bevinden, vrij zijn en bevoegd tot het genot van de burgerlijke rechten. Dit laatste betekent dat de genoemde personen rechtsbevoegd zijn, dus rechtssubject – subject van rechten en verplichtingen – kunnen zijn (zie ook art. 6 UVRM en art. 16 IVBPR ). Artikel 1:1 lid 2 BW voegt hieraan toe dat persoonlijke dienstbaarheden, van welke aard of onder welke benaming ook, niet worden geduld, hetgeen betekent dat Nederland geen slavernij kent. Soortgelijke voorschriften treft men aan in artikel 4 UVRM, artikel 4 lid 1 EVRM en artikel 8 lid 1 IVBPR

    Characterization and Electrolysis of Zn and Cu 2,6-diacetylpyridine bis(2-hydrazinopyridine)

    Get PDF
    With increasing demands for fuel and concerns over climate change, the search for sustainable energy sources is ever growing. Hydrogen is a potential solution to these issues, as it is clean, recyclable, and efficient. However, hydrogen must be generated, unlike other fuel sources that are naturally ready for use. The most sustainable method for hydrogen production involves water electrolysis, as no pollution is generated. The water splitting process contains a cathodic hydrogen evolution reaction (HER) and an anodic oxygen evolution reaction (OER). These reactions require a catalyst to overcome the kinetic barrier present and meet the high voltage requirements for driving the electrolysis reaction. Platinum based catalysts are the most effective in these reactions, but the scarcity and high prices of platinum materials make it undesirable for use. Exploration of still efficient but more sustainable electrocatalysts has intensified to replace the expensive and scare platinum materials. The Grapperhaus group has worked on redox non-innocent ligands with abundant, first-row metals to create an inexpensive catalyst for HER. The redox non-innocent ligand acts to confer nobility onto the first-row metals allowing them to do two electron chemistry which is required for HER. Herein, we describe the characterization and electrocatalytic ability of Zn and Cu 2,6- diacetylpyridine bis(2-hydrazinopyridine) in methanol with triethylammonium hexafluorophosphate

    Substrate Binding Preferences and p\u3cem\u3eK\u3c/em\u3e\u3csub\u3ea\u3c/sub\u3e Determinations of a Nitrile Hydratase Model Complex: Variable Solvent Coordination to [(bmmp-TASN)Fe]OTf

    Get PDF
    The five-coordinate iron-dithiolate complex (N,N′-4,7-bis-(2′-methyl-2′-mercatopropyl)-1-thia-4,7-diazacyclononane)iron(III), [LFe]+, has been isolated as the triflate salt from reaction of the previously reported LFeCl with thallium triflate. Spectroscopic characterization confirms an S = 1/2 ground state in non-coordinating solvents with room temperature μeff = 1.78 μΒ and electron paramagnetic resonance (EPR) derived g-values of g1 = 2.04, g2 = 2.02 and g3 = 2.01. [LFe]+ binds a variety of coordinating solvents resulting in six-coordinate complexes [LFe-solvent]+. In acetonitrile the low-spin [LFe-NCMe]+ (g1 = 2.27, g2 = 2.18, and g3 = 1.98) is in equilibrium with [LFe]+ with a binding constant of Keq = 4.7 at room temperature. Binding of H2O, DMF, methanol, DMSO, and pyridine to [LFe]+ yields high-spin six-coordinate complexes with EPR spectra that display significant strain in the rhombic zero-field splitting term E/D. Addition of 1 equiv of triflic acid to the previously reported diiron species (LFe)2O results in the formation of [(LFe)2OH]OTf, which has been characterized by X-ray crystallography. The aqueous chemistry of [LFe]+ reveals three distinct species as a function of pH: [LFe-OH2]+, [(LFe)2OH]OTf, and (LFe)2O. The pKa values for [LFe-OH2]+ and [(LFe)2OH]OTf are 5.4 ± 0.1 and 6.52 ± 0.05, respectively

    On the feasibility of N2 fixation via a single-site FeI/FeIV cycle: Spectroscopic studies of FeI(N2)FeI, FeIV=N, and related species

    Get PDF
    The electronic properties of an unusually redox-rich iron system, [PhBPR 3]FeNx (where [PhBPR 3] is [PhB(CH2PR2)3]−), are explored by Mössbauer, EPR, magnetization, and density-functional methods to gain a detailed picture regarding their oxidation states and electronic structures. The complexes of primary interest in this article are the two terminal iron(IV) nitride species, [PhBPiPr 3]FeN (3a) and [PhBPCH2Cy 3]FeN (3b), and the formally diiron(I) bridged-Fe(μ-N2)Fe species, {[PhBPiPr 3]Fe}2(μ-N2) (4). Complex 4 is chemically related to 3a via a spontaneous nitride coupling reaction. The diamagnetic iron(IV) nitrides 3a and 3b exhibit unique electronic environments that are reflected in their unusual Mössbauer parameters, including quadrupole-splitting values of 6.01(1) mm/s and isomer shift values of −0.34(1) mm/s. The data for 4 suggest that this complex can be described by a weak ferromagnetic interaction (J/D < 1) between two iron(I) centers. For comparison, four other relevant complexes also are characterized: a diamagnetic iron(IV) trihydride [PhBPiPr 3]Fe(H)3(PMe3) (5), an S = 3/2 iron(I) phosphine adduct [PhBPiPr 3]FePMe3 (6), and the S = 2 iron(II) precursors to 3a, [PhBPiPr 3]FeCl and [PhBPiPr 3]Fe-2,3:5,6-dibenzo-7-aza bicyclo[2.2.1]hepta-2,5-diene (dbabh). The electronic properties of these respective complexes also have been explored by density-functional methods to help corroborate our spectral assignments and to probe their electronic structures further

    Embedding the Ni-SOD mimetic Ni-NCC within a polypeptide sequence alters specificity of the reaction pathway

    Get PDF
    This document is the Accepted Manuscript version of a Published Work that appeared in final form in the Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/ic301175f.The unique metal abstracting peptide (MAP) asparagine-cysteine-cysteine (NCC) binds nickel in a square planar 2N:2S geometry and acts as a mimic of the enzyme nickel superoxide dismutase (Ni-SOD). The Ni-NCC tripeptide complex undergoes rapid, site-specific chiral inversion to DLD-NCC in the presence of oxygen. Superoxide scavenging activity increases proportionally with the degree of chiral inversion. Characterization of the NCC sequence within longer peptides with absorption, circular dichroism (CD), and magnetic CD (MCD) spectroscopies and mass spectrometry (MS) shows that the geometry of metal coordination is maintained, though the electronic properties of the complex are varied to a small extent due to bis-amide, rather than amine/amide, coordination. In addition, both the Ni-tripeptides and Ni-pentapeptides have a −2 charge. The study here demonstrates that the chiral inversion chemistry does not occur when NCC is embedded in a longer polypeptide sequence. Nonetheless, the superoxide scavenging reactivity of the embedded Ni-NCC module is similar to that of the chirally inverted tripeptide complex, which is consistent with a minor change in reduction potential for the Ni-pentapeptide. Together, this suggests that the charge of the complex could affect the SOD activity as much as a change in primary coordination sphere. In Ni-NCC and other Ni-SOD mimics, changes in chirality, superoxide scavenging activity, and oxidation of the peptide itself all depend on the presence of dioxygen or its reduced derivatives (e.g., superoxide), and the extent to which each of these distinct reactions occurs is ruled by electronic and steric effects that emenate from the organization of ligands around the metal center

    Cobalamin-Independent Methionine Synthase (MetE): A Face-to-Face Double Barrel That Evolved by Gene Duplication

    Get PDF
    Cobalamin-independent methionine synthase (MetE) catalyzes the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine (Hcy) without using an intermediate methyl carrier. Although MetE displays no detectable sequence homology with cobalamin-dependent methionine synthase (MetH), both enzymes require zinc for activation and binding of Hcy. Crystallographic analyses of MetE from T. maritima reveal an unusual dual-barrel structure in which the active site lies between the tops of the two (βα)(8) barrels. The fold of the N-terminal barrel confirms that it has evolved from the C-terminal polypeptide by gene duplication; comparisons of the barrels provide an intriguing example of homologous domain evolution in which binding sites are obliterated. The C-terminal barrel incorporates the zinc ion that binds and activates Hcy. The zinc-binding site in MetE is distinguished from the (Cys)(3)Zn site in the related enzymes, MetH and betaine–homocysteine methyltransferase, by its position in the barrel and by the metal ligands, which are histidine, cysteine, glutamate, and cysteine in the resting form of MetE. Hcy associates at the face of the metal opposite glutamate, which moves away from the zinc in the binary E·Hcy complex. The folate substrate is not intimately associated with the N-terminal barrel; instead, elements from both barrels contribute binding determinants in a binary complex in which the folate substrate is incorrectly oriented for methyl transfer. Atypical locations of the Hcy and folate sites in the C-terminal barrel presumably permit direct interaction of the substrates in a ternary complex. Structures of the binary substrate complexes imply that rearrangement of folate, perhaps accompanied by domain rearrangement, must occur before formation of a ternary complex that is competent for methyl transfer

    Interplay of Magnetic Exchange Interactions and Ni-S-Ni Bond Angles in Polynuclear Nickel(II) Complexes

    Full text link
    The ability of bridging thiophenolate groups to transmit magnetic exchange interactions between paramagnetic Ni(II) ions has been examined. For this purpose, dinuclear and trinuclear Ni(II)-complexes were prepared and fully characterized by IR- and UV-vis spectroscopy, X-ray crystallography, static magnetization measurements and high-field electron spin resonance (HF-ESR). We compare structural and magnetic properties of the two Ni(II)-complexes and discuss the relationships between magnetic interactions and chemical bonding.Comment: 10 page
    corecore