Suchergebnisse

The dramatic consequences that the orientation adopted by the molecular dipoles, in diverse arrays of chloroaluminum phthalocyanine (ClAlPc) on Au(111), have on the ulterior adsorption and growth of C60 are explored by means of an all scanning probe microscopy approach. The unidirectional downwards organization of the molecular dipoles at the first layer reduces charge transfer from the metal to C60. Imbalance between attractive and repulsive interactions of the fullerenes are crucial for their ordered supramolecular aggregation. The effect at the basis of such self-assembling seems to be released by the all upwards dipole orientation adopted on the ClAlPc second layer. The low electronic corrugation of the bilayer repercutes in a higher mobility of the fullerenes which for similar coverages diffuse large distances to reach uncoverd first layer regions. Density functional theory calculations corroborate the experimental observations indicating the relevance of charge transfer, potential energy surface corrugation, C60 on-surface diffusion barriers and screening. The structure of the co-adsorbed C60 and ClAlPc layers strongly depends on the deposition sequence. Phase-separation, where each molecule adopts the single-component assembly, occurs if C60 is deposited first. The present results contribute to understanding the influence of the dipolar nature of molecular layers on the electronic and structure of donor/acceptor heterojunctions, which is crucial for device design via engineering the energy levels algingment at the organic-organic and organic-metal interfaces. ; This work has been supported by the Spanish Government under the project PID2019-110907GB-I00, MAT2016-77852-C2- 1-R and MAT2017-85089-C2-1-R (AEI/FEDER, UE) and the ''Severo Ochoa'' Program for Centres of Excellence in R&D (CEX2019-000917-S). We also acknowledge the Generalitat de Catalunya grant 2017 SGR668. J.I.M. acknowledges Comunidad de Madrid via "Programa de Investigación Tecnologías 2018" (FOTOART-CM S2018/NMT-4367), and the EU Innovation Program under grant agreement 881603 (GrapheneCore3- Graphene-based disruptive technologies). ; Peer reviewed

The nontrivial effect of molecular dipoles on the surface work function of metals is explored for the unidirectional ordered arrays forming the first and second layers of chloroaluminum phthalocyanine on Au(111). This phthalocyanine is a nonplanar molecule with permanent electric dipole perpendicular to its molecular π-plane that can adopt two distinct configurations (Cl-up and Cl-down) when adsorbed on surfaces. The ordered array forming the first layer is known to consist of all Cl-up molecules, whereas the less-studied second layer is formed by molecules in the Cl-down configuration. The inverted orientation of the molecules in these two layers constitutes our benchmark system to investigate the influence of the dipole array orientation on the surface work function. The present study includes an experimental and theoretical approach that combines diverse imaging and spectroscopic scanning probe microscopies, in ultrahigh vacuum, with first-principles density functional theory-based atomistic simulations. Experiment and theory show a chiral organization transferred from the first layer to the growing film that is reflected in the electronic structure. We demonstrate that the obtained surface work function changes are smaller in magnitude than expected from a dipolar approximation because of charge rearrangement at and beyond the monolayer. We provide understanding of the crucial interplay between the interlayer and organic/metal interactions and quantify their effect on the electron density distribution and on the work function changes. ; This work has been supported by the Spanish Government under projects MAT2013-47869-C4-1-P, MAT2015-72848- EXP /AEI and MAT2016-77852-C2-1-R (AEI/FEDER, UE) and the Generalitat de Catalunya 2017 SGR 668. R. P-R. thanks financial support through BES-2014-067942. We acknowledge the specific agreement between ICMAB-CSIC and the Synchrotron Light Facility ALBA and the Spanish MINECO through the project MAT2015-68994-REDC and the "Severo Ochoa" Program for Centers of Excellence in R&D (SEV-2015-0496). J.I.M. acknowledges the financial support by the Spanish MINECO via grant no. MAT2017-85089-C2-1- R and the "Ramon y Cajal ́ " Program (grant no. RYC-2015- 17730), and the EU through the Innovation Program (grant 696656: Graphene Core1. Graphene-based disruptive technologies), as well as the use of computing resources from CTICSIC. ; Peer reviewed

We report on the stepwise formation of N-doped nanohelicenes, nanographenes, nanodomes and graphenes from the same heteroaromatic precursor through subsequent dehydrogenations on Pt(111) upon thermal annealing. The combined experimental (UHV-STM) and computational (DFT) studies provide a full atomistic description of the intermediate reaction stages. This journal is © The Royal Society of Chemistry. ; This work is supported by Spanish research projects MAT 2011-26534 and CSD2007-41, European Union Seventh Framework Programme under the grant agreement no 604391 Graphene Flagship, the Czech Science Foundation (P207/10/2207) and the Institute of Organic Chemistry and Biochemistry AS CR (RVO: 61388963). JIM acknowledges the CSIC-JAEDOC Fellowship Program. ; Peer Reviewed

Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650 °C). Using a two step deposition process– nucleation and growth– by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω sq−1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies. ; This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 696656. JA acknowledges funding from FPI Program of MINECO (BES-2012-058600). JIM acknowledges funding from the ERC-Synergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS) and computing resources from CTI-CSIC. CM acknowledges the financial support by the 'Ramón y Cajal' Program of MINECO (RYC-2014-16626). ; Peer reviewed

The effect of different deprotonators as well as washing steps and drying procedure on the synthesis of ZIF-8 from the mother liquor was investigated. The morphology, thermal stability, crystallinity, and surface area of the synthesized MOF were investigated. In addition, life-cycle assessment (LCA) or, in other words, eco-balance, was implemented as well. LCA compares the full range of environmental effects associated with the product by evaluating all inputs and outputs of material flows and predicting how such flow will affect the environment. ZIF-8 nanocrystals were synthesized from the recycled mother liquors using NaOH or NH4OH thus preserving the main characteristics of the ZIF-8 nanoparticles derived from the initial synthesis. The rest of the characterization methods confirmed the suitability of the synthesis methodology considering the phase purity of the obtained ZIF-8 and nanometer size particles. This procedure enabled us not only to obtain phase pure ZIF-8 but also to substantially decrease the amount of solvent used for washing making it a sustainable process. ; This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 760944 (MEMBER project). Also, financial support from the Spanish Ministry of Science, Innovation and Universities and FEDER (MAT2016-77290-R), the Aragón Government (T43-17R) and the ESF is gratefully acknowledged. ; Peer reviewed

Direct reactions under ambient conditions between CuX (X = Br, I) and thiobenzamide (TBA) were carried out at different ratios, giving rise to the formation of a series of one-dimensional (1D) coordination polymers, (CPs) [CuI(TBA)]n (1), [Cu3I3(TBA)2]n (4), and [CuBr(TBA)]n (5), as well as two molecular complexes, [CuI(TBA)3] (2) and [Cu2I2(TBA)4]·2MeCN (3). Recrystallization of 1 and 5 yielded a series of isostructural 1D CP solvated species, [CuI(TBA)·S]n]n (1·S; S = tetrahydrofuran, acetone, methanol) and [CuBr(TBA)·S]n (5·S; S = tetrahydrofuran, acetone), respectively. Similar reactions between CuI and 1,4-dithiobenzamide (DTBA) allowed the isolation of a series of two-dimensional (2D) CPs [CuI(DTBA)·S]n (6·S; S = N,N-dimethylformamide, acetonitrile, methanol). Interestingly, 1·S and 5·S showed variable luminescence and electrical semiconductivity depending on the different solvents located in their structures. Thus, 1 and 5 could display potential application for sensing volatile organic vapors by virtue of the significant changes in their emission upon solvent exposure, even by the naked eye. Theoretical calculations have been used to rationalize these electronic properties. ; MINECO (Grants MAT2016-77608-C3-1-P, MAT2016-75883-C2-1-P, and MAT2017-85089-C2-1-R; Ramon y Cajal, Grant RYC-2015-17730), Ministerio de Ciencia, Innovación y Universidades (Grant CTQ2016-75816-C2-1-P), and European Union's Horizon 2020 research and innovation programme (Grant 785219; Graphene Flagship–core2). ; Peer reviewed

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry 58.5 (2019): 3290-3301, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.8b03364 ; Direct reactions under ambient conditions between CuX (X = Br, I) and thiobenzamide (TBA) were carried out at different ratios, giving rise to the formation of a series of one-dimensional (1D) coordination polymers, (CPs) [CuI(TBA)] n (1), [Cu 3 I 3 (TBA) 2 ] n (4), and [CuBr(TBA)] n (5), as well as two molecular complexes, [CuI(TBA) 3 ] (2) and [Cu 2 I 2 (TBA) 4 ]·2MeCN (3). Recrystallization of 1 and 5 yielded a series of isostructural 1D CP solvated species, [CuI(TBA)·S] n ] n (1·S; S = tetrahydrofuran, acetone, methanol) and [CuBr(TBA)·S] n (5·S; S = tetrahydrofuran, acetone), respectively. Similar reactions between CuI and 1,4-dithiobenzamide (DTBA) allowed the isolation of a series of two-dimensional (2D) CPs [CuI(DTBA)·S] n (6·S; S = N,N-dimethylformamide, acetonitrile, methanol). Interestingly, 1·S and 5·S showed variable luminescence and electrical semiconductivity depending on the different solvents located in their structures. Thus, 1 and 5 could display potential application for sensing volatile organic vapors by virtue of the significant changes in their emission upon solvent exposure, even by the naked eye. Theoretical calculations have been used to rationalize these electronic properties ; MINECO (Grants MAT2016-77608-C3-1-P, MAT2016-75883-C2-1-P, and MAT2017-5089-C2-1-R; Ramon y Cajal, Grant RYC-2015-17730), Ministerio de Ciencia, Innovacion y Universidades (Grant CTQ2016-75816-C2-1-P), and European Union's Horizon 2020 research and innovation programme (Grant 785219; Graphene Flagship−core2)

The intrinsic atomic mechanisms responsible for electronic doping of epitaxial graphene Moirés on transition metal surfaces is still an open issue. To better understand this process we have carried out a first-principles full characterization of the most representative Moiré superstructures observed on the Gr/Pt(111) system and confronted the results with atomically resolved scanning tunneling microscopy experiments. We find that for all reported Moirés the system relaxes inducing a non-negligible atomic corrugation both, at the graphene and at the outermost platinum layer. Interestingly, a mirror "anti-Moiré" reconstruction appears at the substrate, giving rise to the appearance of pinning-points. We show that these points are responsible for the development of the superstructure, while charge from the Pt substrate is injected into the graphene, inducing a local n-doping, mostly localized at these specific pinning-point positions. ; We acknowledge funding from the Spanish MINECO (Grant MAT2014-54231-C4-1-P), the EU via the ERC-Synergy Program (Grant ERC-2013-SYG-610256 Nanocosmos), and computing resources from CTI-CSIC. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. J.I.M. acknowledges funding from both the CSIC-JaeDoc Fellowship Program (co-funded by the European Social Fund) and Nanocosmos. P.M. was supported by the "Rafael Calvo Rodés" Program. ; Peer reviewed

The hydrogen (H) dimer structures formed upon room-temperature H adsorption on single layer graphene (SLG) grown on SiC(0001) are addressed using a combined theoretical–experimental approach. Our study includes density functional theory (DFT) calculations for the full (6√3 × 6√3)R30° unit cell of the SLG/SiC(0001) substrate and atomically resolved scanning tunneling microscopy images determining simultaneously the graphene lattice and the internal structure of the H adsorbates. We show that H atoms normally group in chemisorbed coupled structures of different sizes and orientations. We make an atomic scale determination of the most stable experimental geometries, the small dimers and ellipsoid-shaped features, and we assign them to hydrogen adsorbed in para dimers and ortho dimers configuration, respectively, through comparison with the theory. ; P.M acknowledges financial support from a R. C. Rodes grant. The research leading to these results has received funding from the European Union Seventh Framework Program under grant agreement no. 604391 Graphene Flagship. We acknowledge financial support by the Spanish project MAT2011-26534. M.S., P.M., and P.J acknowledge the financial support of GACR project no. 14-02079S. ; Peer reviewed

We have deposited 4-aminophenol on Pt(111) surfaces in ultra-high vacuum and studied the strength of its adsorption through a combination of STM, LEED, XPS and ab initio calculations. Although an ordered (2√3 × 2√3)R30° phase appears, we have observed that molecule–substrate interaction dominates the adsorption geometry and properties of the system. At RT the high catalytic activity of Pt induces aminophenol to lose the H atom from the hydroxyl group, and a proportion of the molecules lose the complete hydroxyl group. After annealing above 420 K, all deposited aminophenol molecules have lost the OH moiety and some hydrogen atoms from the amino groups. At this temperature, short single-molecule oligomer chains can be observed. These chains are the product of a new reaction that proceeds via the coupling of radical species that is favored by surface diffusion. ; We acknowledge funding from the Spanish MINECO (Grants MAT2014-54231-C4-1-P, MAT2014-54231-C4-4-P and MAT2013-47898-C2-2-R), the EU via the ERC-Synergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS), and computing resources from CTI-CSIC. MKS and GOI acknowledge financial support from FCT (Grant No. PTDC/CTM-NAN/121108/2010 and SFRH/BPD/90562/2012), Ministry of Science and Technology, Portugal. HJS would like to acknowledge the MICINN for a "Ramón y Cajal" Senior Research Fellowship, Spain. JIM acknowledges funding from both the CSIC-JAE-Doc Fellowship Program (co-funded by the European Social Fund). The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. ; Peer reviewed

A new compound (1) formed by two antiparallelly disposed tetracyano thienoquinoidal units has been synthesized and studied by electrochemistry, UV/Vis-NIR, IR, EPR, and transient spectroscopy. Self-assembly of 1 on a Au(111) surface has been investigated by scanning tunneling microscopy. Experiments have been rationalized by quantum chemical calculations. 1 exhibits a unique charge distribution in its anionic form, with a gradient of charge yielding a neat molecular in-plane electric dipole momentum, which transforms out-of-plane after surface deposition due to twisted→folded conformational change and to partial charge transfer from Au(111). Intermolecular van der Waals interactions and antiparallel trapezoidal shape fitting lead to the formation of an optimal dense on Au(111) two-dimensional assembly of 1. ; The authors thank the Spanish Ministry of Science, Innovation and Universities MCIU (projects CTQ2017-83531-R, RED2018-102815-T, MAT2017-85089-C2-1-R), Centro de Excelencia Severo Ochoa grants (SEV-2016-0686, SEV-2015-0496 and FUNFUTURE CEX2019-000917-S) and the CAM (QUIMTRONIC-CM project Y2018/NMT-4783). We thank MINECO/FEDER of the Spanish Government (projects PGC2018-098533-B-100 and PID2019-109555GB-I00), the Eusko Jaurlaritza (Basque Government, project PIBA19-0004) and the Junta de Andalucía, Spain (UMA18FEDERJA057). We also thank the Research Central Services (SCAI) of the University of Málaga and the Donostia International Physics Center (DIPC) Computer Center. We thank Dr. Juwon Oh and Prof. Donhgo Kim from the Spectroscopy Laboratory for Functional π-electronic Systems and Department of Chemistry, Yonsei University in Korea for the generous gift of the TRIR and UV/Vis transient absorption spectroscopy data. ; Peer reviewed

Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular adsorption or unruly functionalization. We show hereafter a mechanism for promoting highly specific covalent bonding of any amino-terminated molecule and a description of the operating processes. We show, by different experimental techniques and theoretical methods, that the excess of charge at carbon dangling-bonds formed on single-atomic vacancies at the graphene surface induces enhanced reactivity towards a selective oxidation of the amino group and subsequent integration of the nitrogen within the graphene network. Remarkably, functionalized surfaces retain the electronic properties of pristine graphene. This study opens the door for development of graphene-based interfaces, as nano-bio-hybrid composites, fabrication of dielectrics, plasmonics or spintronics. ; The research leading to these results has received funding from the Spanish MINECO (through Grants No. MAT2014-54231-C4-1-P, MAT2016-80394-R, RYC-2014-16626 and RYC-2015-17730), from the EU via the ERC-Synergy Program (Grant No. ERC-2013-SYG-610256 Nanocosmos) and the European Union Seventh Framework Program (Grant No. 604391 Graphene Flagship), and from the Comunidad Autónoma de Madrid (CAM) via the MAD2D-CM Program (Grant No. S2013/MIT-3007). We also thank the computing resources from CTI-CSIC. R.L. acknowledges financial support from Spanish MINECO under Grant agreement No. CONSOLIDER INGENIO CSD2009-00013. ; Peer reviewed

Taming the magnetic anisotropy of lanthanides through coordination environments is crucial to take advantage of the lanthanides properties in thermally robust nanomaterials. In this work, the electronic and magnetic properties of Dy-carboxylate metal–organic networks on Cu(111) based on an eightfold coordination between Dy and ditopic linkers are inspected. This surface science study based on scanning probe microscopy and X-ray magnetic circular dichroism, complemented with density functional theory and multiplet calculations, reveals that the magnetic anisotropy landscape of the system is complex. Surface-supported metal–organic coordination is able to induce a change in the orientation of the easy magnetization axis of the Dy coordinative centers as compared to isolated Dy atoms and Dy clusters, and significantly increases the magnetic anisotropy. Surprisingly, Dy atoms coordinated in the metallosupramolecular networks display a nearly in-plane easy magnetization axis despite the out-of-plane symmetry axis of the coordinative molecular lattice. Multiplet calculations highlight the decisive role of the metal–organic coordination, revealing that the tilted orientation is the result of a very delicate balance between the interaction of Dy with O atoms and the precise geometry of the crystal field. This study opens new avenues to tailor the magnetic anisotropy and magnetic moments of lanthanide elements on surfaces. ; The ALBA synchrotron is acknowledged for providing beam time at BOREAS beamline (proposal number 2015091454). This project has received funding from the European Research Council (ERC, grant 766555) and Marie Sklodowska-Curie Actions (MSCA, project 894924) under the European Union's Horizon 2020 research and innovation programme. This work has been financed by the Spanish Ministerio de Economía, Industria y Competitividad (projects FIS2016-78591-C3-1-R, RTI2018-097895-B-C42, MAT2016-78293-C6-2-R, MAT2017-85089-C2-1-R, and PID2019-107338RB-C65); the Comunidad de Madrid (Projects S2013/MIT-2850, P2018/NMT4321, and S2018/NMT-4367); the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (Contract No. EFA 194/16 TNSI); and "Severo Ochoa" Programme for Centres of Excellence in R&D (grants SEV-2016-0686, and SEV-2017-0706).

Technologically useful and robust graphene-based interfaces for devices require the introduction of highly selective, stable, and covalently bonded functionalities on the graphene surface, whilst essentially retaining the electronic properties of the pristine layer. This work demonstrates that highly controlled, ultrahigh vacuum covalent chemical functionalization of graphene sheets with a thiol-terminated molecule provides a robust and tunable platform for the development of hybrid nanostructures in different environments. We employ this facile strategy to covalently couple two representative systems of broad interest: metal nanoparticles, via S–metal bonds, and thiol-modified DNA aptamers, via disulfide bridges. Both systems, which have been characterized by a multitechnique approach, remain firmly anchored to the graphene surface even after several washing cycles. Atomic force microscopy images demonstrate that the conjugated aptamer retains the functionality required to recognize a target protein. This methodology opens a new route to the integration of high-quality graphene layers into diverse technological platforms, including plasmonics, optoelectronics, or biosensing. With respect to the latter, the viability of a thiol-functionalized chemical vapor deposition graphene-based solution-gated field-effect transistor array was assessed. ; This work was supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No 696656 (Graphene Flagship-core 1) and no 785219 (Graphene Flagship −core 2); UE FP7 ideas: ERC (grant ERC-2013-SYG-610256 Nanocosmos) and Spanish MINECO grants MAT2014-54231-C4-1-P, MAT2014-54231-C4-4-P, MAT2017-85089-C2-1-R, MAT2014-59772-C2-2-P, and BIO2016-79618-R (funded by EU under the FEDER programme), as well as the Nanoavansens program from the Community of Madrid (S2013/MIT-3029). This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MINECO and also the ICTS NANBIOSIS, more specifically the Micro-Nano Technology Unit of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the IMB-CNM. We are grateful to Matthias Muntwiler for his assistance with experiments in the PEARL beamline in the SLS facility. Finally, we acknowledge the TEM and ICP services at the CNB and ICMM institutes, respectively. CSS acknowledges the MINECO for a Juan de la Cierva Incorporación grant (IJCI-2014-19291). M. Marciello is grateful to the Comunidad de Madrid (CM) and European Social Fund (ESF) for supporting her research work through the I+D Collaborative Programme in Biomedicine NIETO-CM (B2017-BMD3731). ; Peer reviewed