Characterization of some Italian V. vinifera L. grape varieties on the basis of their flavonol profile

"Suspect screening metabolomics" is a mid-way approach between "targeted" and "untargeted" analysis. For this aim, a new database of putative grape and wine metabolites (GrapeMetabolomics ) was expressly constructed. Currently, this database contains around 1,100 compounds. By performing UHPLC/QTOF mass spectrometry analysis in both positive and negative ionization mode, in a grape extract averaging 320–450 putative compounds are identified. Most of these compounds are important grape metabolites, including flavonols, anthocyanins, and stilbene derivatives. In the present study, this approach was focalized on the characterization of flavonols of 18 important Italian red and white grape varieties and the method provided the identification of 15 flavonols. By performing statistical analysis (Principal Component Analysis and Cluster Analysis), the effect of the variety on the flavonol composition of the grapes was studied. Both the red and white samples fell into three different groups, respectively, on the basis of their flavonol profiles. Because the samples were cultivated in the same vineyard, their profile potentially was not affected by cultural or environmental factors. Anyway, these preliminary results will have to be confirmed by the study of grape samples collected in different years and from different vineyards

Magnetism of Cr10 wheels on Au(111) and Cu(111) surfaces

Trabajo presentado al X Meeting de GEFES (División de Física de la Materia Condensada de la Real Sociedad Española de Física), celebrado en Valencia del 24 al 26 de enero de 2018We report on the magnetic properties of {Cr10} wheels (Cr10(OMe)20(O2CCMe)10) UHVsublimated on Cu(111) and Au(111) single-crystals investigated by means of by XAS & XMCD, SQUID magnetometry and STM. We discuss the magnetic anisotropy and magnetic moment field-dependence of the grafted {Cr10} molecules, as a function of the metallic substrate and layer thickness, and compare it with bulk material. Our results demonstrate that evaporated molecules show negligible anisotropy and weak dependence with the substrate. A combination of XMCD and SQUID magnetometry show that Mono- and Multilayer {Cr10} samples exhibit a magnetic behavior stemming from a S = 9 ground state, ruling out some previous results. Montecarlo simulations show that the magnetic evolution can be explained by {Cr10} molecules magneticaly consisting of two semi-crowns containing 4 Cr ions interacting ferromagnetically, separated by 2 Cr ions with antiferromagnetic interactions, giving rise to the ground S = 9 state, in agreement with previous EPR data in literature. Evaporation of {Cr10} onto a substrate producing subtle structural changes induce strong changes in the Cr-Cr interactions and distinct magnetic behavior from the bulk.Peer Reviewe

Tuning the magnetic moment of high density FePc/Ag(110) phases by oxygen dosing

Resumen del trabajo presentado a la 64th Annual Conference on Magnetism and Magnetic Materials (MMM), celebrada en Las Vegas (USA) del 4 al 8 de noviembre de 2019.Peer reviewe

On-surface synthesis of periodic 7-13 armchair graphene nanoribbons

Resumen del póster presentado a la 10th Conferencia Fuerzas y Túnel, celebrada en Girona (España) del 5 al 7 de septiembre de 2016.-- et al.One of the biggest advantage of the on-surface synthesis of graphene nanoribbons (GNR) with respect to other top-down approaches lies on the capability to synthesize atomically precise GNRs with complex shape and edge structure. These beyond conventional zig-zag and armchair GNRs provide a new route for tailoring electronic and chemical properties. In this work, we report the synthesis and the structural, electrical and chemical characterization of periodically modulated armchair graphene nanoribbons by means of scanning tunneling microscopy and spectroscopy (STM/STS) and X-ray photoemission spectroscopy (XPS). By using the home-designed precursor displayed in Fig. 1a on Au(111), we obtain GNRs were the width is modulated by alternating pairs of 7 and 13 carbon atom chains (Fig.1b). An unconventional surface reconstruction-guided growth leads to ultra-long (~100 nm), parallel GNRs that can even cross monoatomic steps (Fig 1c). At high enough coverage GNRs tend to self-assemble by the lateral interaction between the benzene rings that constitute the 13 AGNR regions (Fig 1d). The tunneling spectra reveal a band gap of 2.5 eV, and the spatial mapping of the HOMO and LUMO orbitals follows the 7-13 modulation of the GNR. The two observations indicate that the electronic confinement seems to be dominated by the inner 7 AGNR, and the band structure modulated by the periodic arrays of the external benzene rings of the 13 A-GNR regions.Peer reviewe

Characterization of Non-Anthocyanic Flavonoids in Some Hybrid Red Grape Extracts Potentially Interesting for Industrial Uses

Previous studies showed that hybrid grapes often have qualitatively and quantitatively higher polyphenolic contents than the common V. vinifera grape varieties. In general, these compounds are studied for grape chemotaxonomy and for nutraceutical purposes due to their relevant antioxidant activity. Non-anthocyanic flavonoid composition of five red hybrid grape varieties produced by crossing of V. vinifera, V. aestivalis, V. cinerea, V. berlandieri, V. labrusca, V. lincecumii, and V. rupestris were studied by liquid chromatography/high-resolution mass spectrometry. Thirty-one compounds were identified, including methylnaringenin, a tetrahydroxy-dimethoxyflavanone-hexoside, two flavonols (quercetin and a pentahydroxyflavone isomer), 20 glycoside flavonols (four quercetin, two myricetin, two kaempferol, three isorhamnetin, one laricitrin, two syringetin, one kaempferide and two dihydroflavonol derivatives; myricetin-glucoside-glucuronide; myricetin-diglucoside; syringetin-dihexoside), three flavan-3-ols (−)-epicatechin, (+)-catechin, (−)-epicatechin gallate) and four proantocyanidins (procyanidin B1, procyanidin B2, procyanidin B3 or B4/B5, procyanidin T2 or T3/T4/C1). Seibel 19881, Seyve Villard 12-347 and Seyve Villard 29-399 were particularly rich in polyphenols. These findings emphasize that these grapes are especially interesting for the production of antioxidant extracts for nutraceutical and pharmaceutical uses

Effect of functional groups on the formation and self-assembly of graphene nanoribbons

Resumen del póster presentado a la 10th Conferencia Fuerzas y Túnel, celebrada en Girona (España) del 5 al 7 de septiembre de 2016.-- et al.Bottom-up processes involving the coupling of molecular precursors enable synthesizing atomically precise, functionalized graphene nanoribbons (GNR). This in turn opens up a new route to tailor the electronic and chemical properties of GNRs. Here we present a comparative study on the growth, structural characterization and chemical stability of zig-zag shaped functionalized GNRs obtained by the surface-assisted coupling of specifically synthesized molecular precursors on the Au(111) surface (Figure 1 a, b). Scanning tunneling microscopy (STM) shows that these precursors lead to straight and almost defect free GNRs (Figure 1c). By means of X-ray photoelectron spectroscopy (XPS) we are able to follow the different reaction steps (namely debromination and cyclodehydrogenation) resulting in the synthesis of the nanoribbons. Moreover, the combination of the two techniques allows us to check the chemical stability of the functional radicals, observing, in particular, that the methoxy group, though not surviving to the cyclodehydrogenation reaction, differently from the fluorine radical, still strongly affects the formation and self-assembly of the nanoribbons on the surface.Peer reviewe

Manipulating the topological interface by molecular adsorbates: adsorption of Co-phthalocyanine on Bi2Se3

et al.Topological insulators are a promising class of materials for applications in the field of spintronics. New perspectives in this field can arise from interfacing metal-organic molecules with the topological insulator spin-momentum locked surface states, which can be perturbed enhancing or suppressing spintronics-relevant properties such as spin coherence. Here we show results from an angle-resolved photemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM) study of the prototypical cobalt phthalocyanine (CoPc)/BiSe interface. We demonstrate that that the hybrid interface can act on the topological protection of the surface and bury the Dirac cone below the first quintuple layer.M.C., L.K., E.P., M.K., and M.M. acknowledge financial support by “Investissement d’avvenir Labex Palm” (Grant No. ANR-10-LABX-0039-PALM) and by the ANR “Iridoti”(Grant No. ANR13-IS04-0001-01). M.P. and A.M. acknowledge support from the Ministerio de Ciencia e Innovación (Grant No. MAT2013-46593-C6-5-P) and the Severo Ochoa Program (MINECO, grant SEV-2013-0295). Work of L.K.-E. is supported by NSF Grants DMR-1420634 and DMR-1312483, and by DODW911NF-13-1-0159. G.D.S. acknowledges Italian MIUR project FIRB “Supracarbon” RBFR10DAK6”. A.G. thanks JU grant Agreement 270722, “Energy for a green society: from sustainable harvesting to smart distribution (ERG)”. A. P. and S. L. thank Elettra-Sincrotrone Trieste S.C.p.A. for economic support. E.V.C. acknowledges funding from the University of Basque Country UPV/EHU (Grant No. GIC07-IT- 756-13), the Departamento de Educacion del Gobierno Vasco (Grant No. FIS2010-275), the Spanish Ministerio de Ciencia e Innovacion (Grant No. 19609-C02-01), the Tomsk State University Academic D.I. Mendeleev Fund Program (Grant No. 8.1.05.2015), the Spanish Ministry of Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P), and Saint Petersburg State University (Project No. 15.61.202.2015). We acknowledge the support by NFFA Trieste.Peer Reviewe

Surface-guided graphene nanoribbon superlattices

Resumen del trabajo presentado al International workshop On-Surface Synthesis (OSS), celebrado en Sant Feliu de Guíxol (España) del 23 al 28 de septiembre de 2018.The on-surface synthesis of graphene nanoribbons (GNRs) has been subject of intense research in recent years. Focused mainly on the realization of GNRs with different shape, edge structure and chemical composition, few studies have paid attention to the control of their distribution throughout the surface, which is critical for integration in devices. The most representative advance in this direction has been the use of stepped surfaces as templates to align the GNRs along one direction at the cm scale, a distribution that can be then replicated after transfer to insulating substrates. Here we show how the herringbone reconstruction can be used as template for inducing different GNR superlattice patterns. Hydrogenated and fluorinated triphenylene derivatives lead to GNRs that interact strongly with the surface reconstruction, which constrains their growth along the fcc domains. This results in a 2D superlattice that replicates the herringbone pattern, and limits the GNR size to the straight domains of the zig-zag. In contrast, GNRs obtained with diphenyl–DBBA undergo a more subtle interaction, where the interaction with the reconstruction is only exploited for the parallel alignment of GNRs without limiting their size. As a consequence we obtain parallel arrays of ultra-long GNRs (>100nm) of different periodicity depending on the coverage (Fig .1). The parallel distribution is optimum for the realization of multichannel electronic devices and optical superlattices, and additionally provides an ideal configuration for the subsequent lateral coupling of GNRs that give rise to nanoporous graphene.Peer reviewe

On-surface synthesis of superlattice arrays of ultra-long graphene nanoribbons

We report the on-surface synthesis of graphene nanoribbon superlattice arrays directed by the herringbone reconstruction of the Au(111) surface. The uniaxial anisotropy of the zigzag pattern of the reconstruction defines a one dimensional grid for directing the Ullmann polymerization and inducing periodic arrays of parallel ultra-long nanoribbons (>100 nm), where the periodicity is varied with coverage at discrete values following a hierarchical templating behavior.C. M. was supported by AGAUR through the FP7-EU under Marie Curie COFUND action 600385. M. P. acknowledges the Spanish Government for financial support through PTA2014-09788-I. Funded by the CERCA Programme/Generalitat de Catalunya. We acknowledge support from the Ministerio de Ciencia e Innovación (MAT2013-46593-C6-2-P, MAT2013-46593-C6-5-P, MAT2016-78293-C6-2-R, MAT2016-78293-C6-4-R and Severo Ochoa No. SEV-2013-0295), the EU project PAMS (610446) the Xunta de Galicia (Centro singular de investigacion de Galicia accreditation 2016–2019, ED431G/09), and the European Regional Development Fund.Peer reviewe