Controlling Carboxyl Deprotonation on Cu(001) by Surface Sn Alloying

We find that for adsorbed terephthalic acid (TPA) molecules surface Sn alloying deactivates the Cu(001) surface by decoupling the adsorbed molecules from the substrate. This effect is investigated for the case of the 0.5 ML phase of the Sn/Cu(001) surface alloy by applying fast X-ray photoemission spectroscopy, scanning tunneling microscopy, near-edge Xray absorption fine structure spectroscopy, and density functional theory calculations. The experimental results conclusively show that the deprotonation reaction of the carboxyl groups occurring in the clean Cu(001) is fully inhibited on this Sn/Cu(001) surface alloy, which allows the molecules to form two-dimensional arrays stabilized by [OH···O] hydrogen bonds. The formed arrays exhibit a crystal structure that is practically indistinguishable from that theoretically obtained for unsupported TPA sheets, suggesting an extremely weak molecule/substrate interaction. This is supported by DFT calculations of the adsorption energy landscape of the TPA sheets formed on the Sn/Cu(001) template: the lateral variation of the adsorption energy (corrugation) is estimated to be less than 0.2 eV, with an adsorption energy per molecule in the range 1.6−1.8 eV and a contribution of each double [OH···O] bond of 1 eV. Finally, the performed thermal desorption experiments show that the TPA sheets remain stable on the surface alloy until their desorption. From these experiments, a value of 1.5 eV was determined for the desorption energy barrier, which is consistent with the important contribution of the [OH···O] bonds to the stability of the sheets as theoretically predicted. The results reported in this study suggest that a gradual activation of the interaction between the TPA molecules and the Cu(001) surface will also be obtained for decreasing Sn coverage.Fil: Carrera, Alvaro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Cristina, Lucila Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Bengió, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Cossaro, A. . Italian National Research Council. Istituto Officina dei Materiali; ItaliaFil: Verdini, A. . Italian National Research Council. Istituto Officina dei Materiali; ItaliaFil: Floreano, L.. Italian National Research Council. Istituto Officina dei Materiali; ItaliaFil: Fuhr, Javier Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Gayone, Julio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Ascolani, Hugo del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentin

2D Cu-TCNQ Metal-Organic Networks Induced by Surface Alloying

We have studied the self-assembly of 7,7,8,8-tetracyanoquinodimethane molecules on the (3√2 × √2)R45° reconstruction of the SnCu(001) surface alloy by means of X-ray photoemission spectroscopy, scanning tunneling microscopy, near-edge X-ray absorption fine structure spectroscopy, and density functional theory calculations. Our results show that surface alloying strongly attenuates the chemical interaction of the molecule with the surface, but it does not inhibit the charge transfer from the substrate to the molecules. The assembly mechanism of the molecules is completely modified with respect to the bare Cu(001) surface. We show that, on the SnCu(100) surface alloy, the strong CN-Cu interaction drives the formation of different coordination structures with native Cu adatoms. We found that the flexible coordination chemistry of Cu allows the formation of three different stable phases, each one with the Cu ions in a different coordination geometry (coordinations 4, 3, and 2). Moreover, we show that both the formation of lateral H bonds between adjacent molecules and the interaction of the Cu ion with the substrate play determinant roles in the stabilization of the structures.Fil: Fuhr, Javier Daniel. Universidad Nacional de Cuyo; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Robino, L.I.. Universidad Nacional de Cuyo; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Rodríguez, L.M.. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Verdini, A.. No especifíca;Fil: Floreano, L.. No especifíca;Fil: Ascolani, Hugo del Lujan. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Gayone, Julio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin

Interplay between Hydrogen Bonding and Molecule-Substrate Interactions in the Case of Terephthalic Acid Molecules on Cu(001) Surfaces

The adsorption and self-assembling properties of terephthalic acid (TPA) molecules deposited on Cu(001) at room temperature have been systematically studied using both experimental and theoretical tools. The system forms two phases at room temperature, the metastable β-phase and the stable 3×3 one. In the case of the β phase, the low-energy electron diffraction and scanning-tunneling microscopy (STM) results indicate that the β phase has a (9 √ 2×2 √ 2)R45◦ unit cell with exactly the same molecular coverage as the 3×3 phase. In addition, the high-resolution X-ray photoelectron spectroscopy O1s spectra indicate that the irreversible β → 3 × 3 transition involves the following two processes: i) deprotonation of the complete carboxyl groups remaining in the metastable phase and ii) re-arrangement of the molecules into the 3×3 configuration. On the other hand, we explored possible molecular configurations for the β phase with different degree of deprotonation (including structures with Cu adatoms) by means of density functional theory calculations. Our theoretical results indicate the formation of strong bonds between the O atoms in carboxylates and the Cu atoms of the surface, which causes a bending of the molecules and a buckling of the first Cu layer. In the 3 × 3 phases, we show that the bending produces observable effects in the molecular STM images. We also observed that the strong interaction between the carboxylates and the Cu atoms at the step edges drives the reorientation of the surface steps along the crystallographic directions.Fil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carrera, Alvaro Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Murillo Quiros, Natalia Maria. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cristina, Lucila Josefina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cossaro, Albano. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; ItaliaFil: Verdini, Alberto. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; ItaliaFil: Floreano, Luca. Consiglio Nazionale delle Ricerche. Istituto Officina dei Materiali; ItaliaFil: Gayone, Julio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ascolani, Hugo del Lujan. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Ubiquitous deprotonation of terephthalic acid in the self-assembled phases on Cu(100)

We performed an exhaustive study of terephthalic acid (TPA) self-assembly on a Cu(100) surface, where first-layer molecules display two sequential phase transitions in the 200-400 K temperature range, corresponding to different stages of molecular deprotonation. We followed the chemical and structural changes by means of high-resolution X-ray photoelectron spectroscopy (XPS) and variable-temperature scanning tunneling microscopy (STM), which were interpreted on the basis of density functional theory (DFT) calculations and photoemission simulations. In order to reveal the spectroscopic contributions of the molecules in different states of deprotonation, we modified the substrate reactivity by deposition of a small amount of Sn, which hampers the deprotonation reaction. We found that the characteristic molecular ribbons of the TPA/Cu(100) α-phase at a low temperature contain a significant fraction of partially deprotonated molecules, in contrast to the expectation of a fully protonated phase, where the self-assembly was claimed to be simply driven by the intermolecular double hydrogen bonds [OH⋯O]. On the basis of our simulations, we propose a model where the carboxylate groups of the partially deprotonated molecules form single hydrogen bonds with the carboxylic groups of the fully protonated molecules. Using real time XPS, we also monitored the kinetics of the deprotonation reaction. We show that the network of mixed single and double hydrogen bonds inhibits further deprotonation up to ∼270 K, whereas the isolated molecules display a much lower deprotonation barrier.Fil: Quiroga Argañaraz, Maria Bernarda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Cristina, Lucila Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Parra Rodríguez, Laura María. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Cossaro, A.. Consiglio Nazionale delle Ricerche; ItaliaFil: Verdini, A.. Consiglio Nazionale delle Ricerche; ItaliaFil: Floreano, L.. Consiglio Nazionale delle Ricerche; ItaliaFil: Fuhr, Javier Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Gayone, Julio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Ascolani, Hugo del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Effect of the 2010 task force criteria on reclassification of cardiovascular magnetic resonance criteria for arrhythmogenic right ventricular cardiomyopathy

Background: We sought to evaluate the effect of application of the revised 2010 Task Force Criteria (TFC) on the prevalence of major and minor Cardiovascular Magnetic Resonance (CMR) criteria for Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) versus application of the original 1994 TFC. We also assessed the utility of MRI to identify alternative diagnoses for patients referred for ARVC evaluation. Methods: 968 consecutive patients referred to our institution for CMR with clinical suspicion of ARVC from 1995 to 2010, were evaluated for the presence of major and minor CMR criteria per the 1994 and 2010 ARVC TFC. CMR criteria included right ventricle (RV) dilatation, reduced RV ejection fraction, RV aneurysm, or regional RV wall motion abnormalities. When quantitative measures of RV size and function were not available, and in whom abnormal size or function was reported, a repeat quantitative analysis by 2 qualified CMR physicians in consensus. Results: Of 968 patients, 220 (22.7%) fulfilled either a major or a minor 1994 TFC, and 25 (2.6%) fulfilled any of the 2010 TFC criterion. Among patients meeting any 1994 criteria, only 25 (11.4%) met at least one 2010 criterion. All patients who fulfilled a 2010 criteria also satisfied at least one 1994 criterion. Per the 2010 TFC, 21 (2.2%) patients met major criteria and 4 (0.4%) patients fulfilled at least one minor criterion. Eight patients meeting 1994 minor criteria were reclassified as satisfying 2010 major criteria, while 4 patients fulfilling 1994 major criteria were reclassified to only minor or no criteria under the 2010 TFC. Eighty-nine (9.2%) patients had alternative cardiac diagnoses, including 43 (4.4%) with clinically significant potential ARVC mimics. These included cardiac sarcoidosis, RV volume overload conditions, and other cardiomyopathies. Conclusions: Application of the 2010 TFC resulted in reduction of total patients meeting any diagnostic CMR criteria for ARVC from 22.7% to 2.6% versus the 1994 TFC. CMR identified alternative cardiac diagnoses in 9.2% of patients, and 4.4% of the diagnoses were potential mimics of ARVC