Long-range repulsive interaction between TTF molecules on a metal surface induced by charge transfer

The low-coverage adsorption of a molecular electron donor, tetrathiafulvalene, on Au(111) is characterized by the spontaneous formation of superlattice of monomers, whose spacing exceeds the equilibrium distance of non-covalent interactions and depends on coverage. The origin of this peculiar growth mode is due to a long-range repulsive interaction between molecules. The analysis of molecular-pair distributions obtained by scanning tunneling microscopy measurements permits us to determine that the nature of TTF intermolecular interactions on Au (111) is electrostatic. A repulsion between molecules is caused by the accumulation of charge due to electron donation into the metal surface, as pictured through density functional theory calculations

Four-year follow-up study in a NF1 Boy with a focal pontine hamartoma

Neurofibromatosis is a collective name for a group of genetic conditions in which benign tumours affect the nervous system. Type 1 is caused by a genetic mutation in the NF1 gene (OMIM 613113) and symptoms can vary dramatically between individuals, even within the same family. Some people have very mild skin changes, whereas others suffer severe medical complications. The condition usually appears in childhood and is diagnosed if two of the following are present: six or more café-au-lait patches larger than 1.5 cm in diameter, axillary or groin freckling, 2 or more Lisch nodules (small pigmented areas in the iris of the eye), 2 or more neurofibromas, optic pathway gliomas, bone dysplasia, and a first-degree family relative with Neurofibromatosis type 1. The pattern of inheritance is autosomal dominant, however, half of all NF1 cases are 'sporadic' and there is no family history. Neurofibromatosis type 1 is an extremely variable condition whose morbidity and mortality is largely dictated by the occurrence of the many complications that may involve any of the body systems. We describe a family affected by NF1 in whom genetic molecular analysis identified the same mutation in the son and father. Routine MRI showed pontine focal lesions in the eight-year-old son, though not in the father. We performed a four years follow-up study and at follow-up pontine hamartoma size remained unchanged in the son, and the father showed still no brain lesions, confirming thus an intra-familial phenotype variability

Formation of dispersive hybrid bands at an organic-metal interface

An electronic band with quasi-one dimensional dispersion is found at the interface between a monolayer of a charge-transfer complex (TTF-TCNQ) and a Au(111) surface. Combined local spectroscopy and numerical calculations show that the band results from a complex mixing of metal and molecular states. The molecular layer folds the underlying metal states and mixes with them selectively, through the TTF component, giving rise to anisotropic hybrid bands. Our results suggest that, by tuning the components of such molecular layers, the dimensionality and dispersion of organic-metal interface states can be engineered

Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111)

The magnetic state and magnetic coupling of individual atoms in nanoscale structures relies on a delicate balance between different interactions with the atomic-scale surrounding. Using scanning tunneling microscopy, we resolve the self-assembled formation of highly ordered bilayer structures of Fe atoms and organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe atoms are encaged in a three-dimensional coordination motif by three T4PT molecules in the surface plane and an additional T4PT unit on top. Within this crystal field, the Fe atoms retain a magnetic ground state with easy-axis anisotropy, as evidenced by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The magnetization curves reveal the existence of ferromagnetic coupling between the Fe centers

Iridium(i) complexes bearing hemilabile coumarin-functionalised N-heterocyclic carbene ligands with application as alkyne hydrosilylation catalysts

A set of iridium(i) complexes of formula IrCl(¿C, ¿2-IRCouR')(cod) or IrCl(¿C, ¿2-BzIRCouR')(cod) (cod = 1, 5-cyclooctadiene; Cou = coumarin; I = imidazolin-2-carbene; BzI = benzimidazolin-2-carbene) have beeen prepared from the corresponding azolium salt and [Ir(µ-OMe)(cod)]2 in THF at room temperature. The crystalline structures of 4b and 5b show a distorted trigonal bipyramidal configuration in the solid state with a coordinated coumarin moiety. In contrast, an equilibrium between this pentacoordinated structure and the related square planar isomer is observed in solution as a consequence of the hemilability of the pyrone ring. Characterization of both species by NMR was achieved at the low and high temperature limits, respectively. In addition, the thermodynamic parameters of the equilibrium, ¿HR and ¿SR, were obtained by VT 1H NMR spectroscopy and fall in the range 22-33 kJ mol-1 and 72-113 J mol-1 K-1, respectively. Carbonylation of IrCl(¿C, ¿2-BzITolCou7, 8-Me2)(cod) resulted in the formation of a bis-CO derivative showing no hemilabile behaviour. The newly synthesised complexes efficiently catalyze the hydrosilylation of alkynes at room temperature with a preference for the ß-(Z) vinylsilane isomer. © The Royal Society of Chemistry

Preparation of Butadienylpyridines by Iridium-NHC-Catalyzed Alkyne Hydroalkenylation and Quinolizine Rearrangement

Iridium(I) N-heterocyclic carbene complexes of formula Ir(¿2O, O’-BHetA)(IPr)(¿2-coe) [BHetA=bis-heteroatomic acidato, acetylacetonate or acetate; IPr=1, 3-bis(2, 6-diisopropylphenyl)imidazolin-2-carbene; coe=cyclooctene] have been prepared by treating Ir(¿2O, O’-BHetA)(¿2-coe)2 complexes with IPr. These complexes react with 2-vinylpyridine to afford the hydrido-iridium(III)-alkenyl cyclometalated derivatives IrH(¿2O, O’-BHetA)(¿2N, C-C7H6N)(IPr) through the iridium(I) intermediate Ir(¿2O, O’-BHetA)(IPr)(¿2-C7H7N). The cyclometalated IrH(¿2O, O’-acac)(¿2N, C–C7H6N)(IPr) complex efficiently catalyzes the hydroalkenylation of aromatic and aliphatic terminal alkynes and enynes with 2-vinylpyridine to afford 2-(4R-butadienyl)pyridines with Z, E configuration as the major reaction products (yield up to 89 %). In addition, unprecedented (Z)-2-butadienyl-5R-pyridine derivatives have been obtained as minor reaction products (yield up to 21 %) from the elusive 1Z, 3gem-butadienyl hydroalkenylation products. These compounds undergo a thermal 6p-electrocyclization to afford bicyclic 4H-quinolizine derivatives that, under catalytic reaction conditions, tautomerize to 6H-quinolizine to afford the (Z)-2-(butadienyl)-5R-pyridine by a retro-electrocyclization reaction. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH Gmb

Estado, mercado y seguridad ciudadana. Análisis de la articulación entre la seguridad pública y privada en España

Los temas relacionados con la seguridad de la población se están convirtiendo en prioridades para las democracias occidentales. La seguridad aparece, cada vez más, como una corresponsabilidad del sector público y privado y de la sociedad civil. Una cuestión de gran importancia social y política es la forma en que se van a articular los diferentes sectores; es decir, el modelo de sistema de seguridad del futuro. El presente artículo analiza, a partir de la sociología de las organizaciones, la forma en que se articula la seguridad privada y pública en España. A partir de un análisis de la legislación, se compara el modelo español con el de otros países de la Unión Europea. Como elementos clave de la articulación se estudian los objetivos y prácticas de los dos sectores, las relaciones de cooperación y conflicto y las fronteras externas e internas del sistema de seguridad español. El análisis se basa en entrevistas a líderes de empresas de seguridad y a responsables de la seguridad pública en España

Constraining the neutrino magnetic moment with anti-neutrinos from the Sun

We discuss the impact of different solar neutrino data on the spin-flavor-precession (SFP) mechanism of neutrino conversion. We find that, although detailed solar rates and spectra allow the SFP solution as a sub-leading effect, the recent KamLAND constraint on the solar antineutrino flux places stronger constraints to this mechanism. Moreover, we show that for the case of random magnetic fields inside the Sun, one obtains a more stringent constraint on the neutrino magnetic moment down to the level of \mu_\nu \lsim few \times 10^{-12}\mu_B, similar to bounds obtained from star cooling.Comment: 4 pages, 3 figures. Final version to appear in Phys. Rev. Let

The solution to a multichannel Bethe potential and its application to pion-nucleus reactions

We solve a radial Schr\"odinger equation for the case of a multichannel square well plus an exponential potential in one of the channels. The solution is obtained by summing exactly the infinite terms of the perturbative series for the evolution operator of the system. Analytical expressions for the scattering matrix and the scattering length are given, a Deser-like formula which connects approximate ground energies and scattering length is obtained for a particular case. Possible physical applications of these results are discussed briefly.Comment: Title changed and other minor changes. 14pages, latex, no figure