Unexpected electron spin density on the axial methionine ligand in Cu suggests its involvement in electron pathways.

The CuA center is a paradigm for the study of long-range biological electron transfer. This metal center is an essential cofactor for terminal oxidases like cytochrome c oxidase, the enzymatic complex responsible for cellular respiration in eukaryotes and in most bacteria. CuA acts as an electron hub by transferring electrons from reduced cytochrome c to the catalytic site of the enzyme where dioxygen reduction takes place.

Electronic Delocalization in Coordination Polymers Based on Bimetallic Carboxylates.

Computational methods (DFT at the B3LYP, PBE0 and m06 levels, MO fragments decomposition, and the broken symmetry approach) have been used to evaluate the influence of the bridging ligand (BL) on the extent of electron delocalization in coordination polymers based on diruthenium tetracarboxylates. The efficiency of three different nitrogenated axial ligands, namely pyrazine (pz), phenazine (phz), and tetrazine (tz), to mediate electron coupling between Ru2(II,II) or Ru2(II,III) centers has been estimated through four different parameters: calculated Ru-N distances, HOMO-LUMO gaps, HOMO and LUMO compositions, and magnetic coupling constants J. All these parameters pointed toward a coordination polymer based on Ru2(II,II) centers axially linked by tetrazine being the best candidate for exhibiting electron delocalization through the Ru2-BL framework.

Simulation of mesogenic diruthenium tetracarboxylates: Development of a force field for coordination polymers of the MMX type.

A classical molecular mechanics force field, able to simulate coordination polymers (CP) based on ruthenium carboxylates (Ru2 (O2CReq )4 Lax) (eq = equatorial group containing aliphatic chains, Lax = axial ligand), has been developed. New parameters extracted from experimental data and quantum calculations on short aliphatic chains model systems were included in the generalized AMBER force field. The proposed parametrization was evaluated using model systems with known structure, containing either short or long aliphatic chains; experimental results were reproduced satisfactorily.

Effect of the protonation degree of a self-assembled monolayer on the immobilization dynamics of a [NiFe] hydrogenase.

Understanding the interaction and immobilization of [NiFe] hydrogenases on functionalized surfaces is important in the field of biotechnology and, in particular, for the development of biofuel cells. In this study, we investigated the adsorption behavior of the standard [NiFe] hydrogenase of Desulfovibrio gigas on amino-terminated alkanethiol self-assembled monolayers (SAMs) with different levels of protonation. Classical all-atom molecular dynamics (MD) simulations revealed a strong correlation between the adsorption behavior and the level of ionization of the chemically modified electrode surface.

Theoretical and experimental studies of diruthenium tetracarboxylates structure, spectroscopy, and electrochemistry.

Quantum mechanical calculations at the density functional theory (DFT) level have been performed on diruthenium tetracarboxylates of different levels of molecular complexity: from unsolvated monomers to oligomers. The agreement between the calculated and experimental molecular structures and vibrational modes of the simple [Ru2(micro-O2CCH3)4]0/+ and [Ru2(micro-O2CCH3)4(H2O)2]0/+ systems made us confident in our calculation methodology. Therefore, it has been applied to the analysis of two different kinds of properties of these compounds: the trends in the UV/vis spectroscopy and electrochemistry along the [Ru2(micro-O2CCH3)4X2]- (X=Cl-, Br-, I-) series, and the crystalline polymorphism related to the polymeric strand conformation in extended Ru2(micro-O2CR)4Cl compounds.

[Mortality and length of stay in a surgical intensive care unit.].

Background And Objectives: Outcome in intensive care can be categorized as mortality related or morbidity related. Mortality is an insufficient measure of ICU outcome when measured alone and length of stay may be seen as an indirect measure of morbidity related outcome. The aim of the present study was to estimate the incidence and predictive factors for intrahospitalar outcome measured by mortality and LOS in patients admitted to a surgical ICU.

A pyrazine bis-adduct of a binuclear rhodium(II) carboxylate containing 3,4,5-triethoxybenzoate as the equatorial ligand.

The title compound, tetrakis(mu-3,4,5-triethoxybenzoato-kappa(2)O:O')bis[(pyrazine-kappa N)rhodium(II)](Rh[bond]Rh), [Rh(2)(C(13)H(17)O(5))(4)(C(4)H(4)N(2))(2)], crystallizes on an inversion centre in the triclinic space group P1. The equatorial carboxylate ligands bridge the two Rh(II) atoms, giving a binuclear lantern-like structure. The pyrazine molecules occupy the two axial coordination sites.