Search

Many molecules quench their fluorescence upon adsorption on surfaces. Herein we show that the interaction of thiabendazole, a widespread used fungicide of the benzimidazole family, with nanosheets of transition metal dichalcogenides, particularly of WS2, leads to a significant increase, more than a factor of 5, of the fluorescence yield. This surprising effect is rationalized by DFT calculations and found to be related to the inhibition of the intramolecular rotation between the benzimidazole and thiazole groups due to a bonding rigidization upon interaction with the MoS2 surface. This non-covalent adsorption leads to a redistribution of the molecular LUMO that blocks the non-radiative energy dissipation channel. This unusual behaviour does not operate either for other molecules of the same benzimidazole family or for other 2D materials (graphene or graphene oxide). Moreover, we found that a linear dependence of the emission with the concentration of thiabendazole in solution, which combined with the specificity of the process, allows the development of a highly sensitive and selective method towards thiabendazole determination that can be applied to real river water samples. An excellent detection limit of 2.7 nM, comparable to the best performing reported methods, is obtained with very good accuracy (E r ≤ 6.1%) and repro-ducibility (RSD ≤ 4.1%) in the concentration range assayed.

Catechols are ubiquitous substances often acting as antioxidants, thus of importance in a variety of biological processes. The Fenton and Haber–Weiss processes are thought to transform these molecules into aggressive reactive oxygen species (ROS), a source of oxidative stress and possibly inducing degenerative diseases. Here, using model conditions (ultrahigh vacuum and single crystals), we unveil another process capable of converting catechols into ROSs, namely an intramolecular redox reaction catalysed by a Cu surface. We focus on a tri-catechol, the hexahydroxytriphenylene molecule, and show that this antioxidant is thereby transformed into a semiquinone, as an intermediate product, and then into an even stronger oxidant, a quinone, as final product. We argue that the transformations occur via two intramolecular redox reactions: since the Cu surface cannot oxidise the molecules, the starting catechol and the semiquinone forms each are, at the same time, self-oxidised and self-reduced. Thanks to these reactions, the quinone and semiquinone are able to interact with the substrate by readily accepting electrons donated by the substrate. Our combined experimental surface science and ab initio analysis highlights the key role played by metal nanoparticles in the development of degenerative diseases., This work was supported by the French National Research Agency through contract ORGANI'SO (ANR-15-CE09-0017). A. C. G. H. and J. C. thank Laurence Magaud for fruitful discussion about the simulation of the structure of the molecules. F. C. thanks Sarah Benchabane for fruitful discussion. C. S. S., J. I. M. and J. A. M. G. acknowledge financial support from Spanish MINECO (MAT2017-85089-C2-1-R, RYC-2015-17730, RYC-2018-024364-I), European Research Council (ERC) under contract (ERC-2013-SYG-610256 NANOCOSMOS), Comunidad de Madrid via Programa de Investigación Tecnologías 2018 (FOTOART-CM S2018/NMT-4367), and the innovation program under grant agreements 785219 and 881603 (GrapheneCore2 and GrapheneCore3-Graphene-based disruptive technologies, respectively). E. M. acknowledges financial support from Région Rhône Alpes (ARC6 program) and the Labex LANEF. J. C. and J. A. M. G. acknowledges financial support from CNRS and CSIC via the IEA program (PIC2017-FR4/07981), under the ORGAN'X project.

8 pags, 4 figs. -- The online version contains supplementary material available at https://doi.org/10.1038/s41467-021-26184-0, Development of sustainable processes for hydrocarbons synthesis is a fundamental challenge in chemistry since these are of unquestionable importance for the production of many essential synthetic chemicals, materials and carbon-based fuels. Current industrial processes rely on non-abundant metal catalysts, temperatures of hundreds of Celsius and pressures of tens of bars. We propose an alternative gas phase process under mild reaction conditions using only atomic carbon, molecular hydrogen and an inert carrier gas. We demonstrate that the presence of CH2 and H radicals leads to efficient C-C chain growth, producing micron-length fibres of unbranched alkanes with an average length distribution between C23-C33. Ab-initio calculations uncover a thermodynamically favourable methylene coupling process on the surface of carbonaceous nanoparticles, which is kinematically facilitated by a trap-and-release mechanism of the reactants and nanoparticles that is confirmed by a steady incompressible flow simulation. This work could lead to future alternative sustainable synthetic routes to critical alkane-based chemicals or fuels., We thank Jose Criado for the artwork schematics of the system, in figures 4 and S1; Funding: We thank the European Research Council for funding support under Synergy grant ERC-2013-SyG, G.A. 610256 (NANOCOSMOS). Also, we acknowledge partial support from the Spanish MINECO through grants PID2020-113142RB-C21, PID2019106315RB-I00, and PID2019-106315RB-I00, EU ERC CoG HyMAP 648319, and from the regional government through project S2018-NMT-4367 (FotoArt-CM). AM acknowledges to the Spanish Ministry of Science (RYC2018-024561-I), to the Regional Government of Aragon (DGA E13_20R), to the National Natural Science Foundation of China (NFSC-21850410448, NSFC-21835002), and to the The Centre for Highresolution Electron Microscopy (ChEM), supported by SPST of ShanghaiTech University under contract No. EM02161943. S.K. and G.H. acknowledge funding from the Turbulent Superstructures Program of the German National Science Foundation (DFG)

In the present work, we investigate two-dimensional (2D) conjugated polymers based on C3-symmetric truxene-based cores at the density functional theory (DFT) level. In total, 27 different 2D polymers have been exhaustively studied with the aim to explore the impact of the following effects on the electronic and charge-transport properties: (i) the nature of the conjugated platform, going from electron-rich truxene (Tx) and triindole (Tr) units to electron-deficient truxenone (To) cores, (ii) the spacing of the cores with different bridges, i.e., phenylene (Ph) or ethynylene (A) units, (iii) the linker position (2,7,12-substitution in the T2 polymers and 3,8,13-substitution in T3 polymers), and (iv) the increased number of ¿-bridges connecting the cores, from three linkers in T2 and T3 to six linkers in T2,3. To this end, we have carried out a large battery of DFT calculations on fragments extracted from the 2D polymers (dimers and trimers) as well as on the corresponding periodic 2D structures (infinite monolayers and self-assembled monolayers) using periodic boundary conditions. Our results show that simultaneous manipulation of the pore surface size and band-gap engineering together with charge-transport parameters can be achieved in these truxene-based 2D polymers by fine-tuning their structural features. The contributions of this study to the overall understanding of the structure¿electronic property relationships of these semiconducting polymers and its correlation with available experimental work are highlighted. Our results provide interesting guidelines to design novel 2D materials with applications ranging from sensing to photocatalysis or electronics., This work was financially supported by the MINECO (CTQ2016-78557-R) and MICINN (PID2019-104125RB-I00) of Spain. JIM acknowledges financial support from Spanish MINECO (MAT2017-85089-C2-1-R, RYC-2015-17730), Comunidad de Madrid via Programa de Investigación Tecnologías 2018 (FOTOART-CM S2018/NMT-4367), and the innovation program under grant agreements 785219 and 881603 (GrapheneCore2 and GrapheneCore3-Graphene-based disruptive technologies, respectively). The work at the University of Málaga wasfunded by the MICINN (PID2019-110305GB-I00) and by the Junta de Andalucıa (P09-FQM-4708, UMA18-FEDERJA-080). S. G.-V. thanks the MINECO for a FPU predoctoral fellowship (FPU17/04908). Computer resources, technical expertise and assistance provided by the SCBI (Supercomputing and Bioinformatics) centre of the University of Málaga are gratefully acknowledged.

The ageing of graphene is an important issue for technological applications. Capping layers are a good way of circumventing this problem. In this work, we propose the use of ultra-thin NaCl films as easilyremovable protective layers. We have carried out a detailed characterization of the NaCl/graphene interface on metal substrates, namely Cu(111) and Ir(111), by means of complementary microscopies, electron diffraction and spectroscopic techniques. Interestingly, we show that NaCl neither interacts in a chemical way with graphene nor intercalates through it. We demonstrate that the NaCl film is stable under ambient conditions, protecting the graphene surface from oxidation. In addition, after removing the protective layer, graphene remains intact., This work has been supported by the EU Graphene Flagship funding (Grant Graphene Core2 785219), the Spanish MINECO (MAT2017-85089-C2-1R, MAT2016-80394-R and RYC-2015-17730) and the EU via the ERC-Synergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS) and the European Structural Funds via FotoArt-CM project (P2018/NMT-4367)., We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI)

Producción Científica, A characteristic fingerprint of atomic clusters is that their properties can vary in a non-smooth way with the cluster size N. This is illustrated herein by studying the cluster size dependence of several properties of neutral CN and cationic C+N carbon clusters: C–C bond lengths, cluster structure, intrinsic cluster stability, ionization energy, and spatial distribution of the reactivity index for charge exchange with electrophiles. Nonetheless, clusters can lose the size dependence of their properties by interaction with other chemical species, which is rationalized in this study by analyzing carbon clusters fully saturated with hydrogen to form linear alkanes, CNH2N+2. In all cases, the lowest energy structures are zigzagging linear chains, the variations of C–C bond lengths and Image ID:c9cp01114e-t1.gif angles with alkane size are very minor and smooth, the stability function shows practically no structure as a function of the alkane size, the ionization energies just decrease smoothly with alkane size, and the spatial distribution of the reactivity index is analogous and highly delocalized in all the alkanes. In summary, the interaction of carbon clusters with hydrogen to form alkanes quenches all the size-dependent features that the carbon clusters originally owned. The arrival at the quenching of the size effects follows an involved path. In each CNHn family with fixed N, the values of the properties of the molecules like the ionization potential, the electron affinity, and others show sizable oscillations as the number of hydrogen atoms grows from the pure carbon cluster to the alkane., Ministerio de Economía, Industria y Competitividad ( grants MAT2017-85089-C2-1-R / RYC-2015-17730), Comunidad de Madrid (FotoArt-CM Project P2018/NMT-4367), Junta de Castilla y León (Grant VA021G18), Universidad de Valladolid (GIR Grupo de Física de Nanoestructuras),y Unión Europea mediante el programa ERC-Synergy (Grant ERC-2013-SYG-610256 Nanocosmos)

One-pot reactions between CuI and methyl or methyl 2-amino-isonicotinate give rise to the formation of two coordination polymers (CPs) based on double zig-zag Cu2I2 chains. The presence of a NH2 group in the isonicotinate ligand produces different supramolecular interactions affecting the Cu-Cu distances and symmetry of the Cu2I2 chains. These structural variations significantly modulate their physical properties. Thus, both CPs are semiconductors and also show reversible thermo/mechanoluminescence. X-ray diffraction studies carried out under different temperature and pressure conditions in combination with theoretical calculations have been used to rationalize the multi-stimuli-responsive properties. Importantly, a bottom-up procedure based on fast precipitation leads to nanofibers of both CPs. The dimensions of these nanofibres enable the preparation of thermo/mechanochromic film composites with polyvinylidene difluoride. These films are tens of nanometers in thickness while being centimeters in length, representing smaller thicknesses so far reported for thin-film composites. This nanomaterial integration of CPs could represent a source of alternative nanomaterials for opto-electronic device fabrication., The authors thank financial support from the Spanish Ministerio de Economía y Competitividad (MAT2016-77608-C3-1-P, MAT2016-75883-C2-2-P, MAT2010-20843-C02-01, MAT2016- 75586-C4-4-P, CTQ2016-75816-C2-1P). J. I. M. acknowledges the financial support by the “Ramón y Cajal” Program of MINECO (Grant RYC-2015-17730) and the EU via the ERCSynergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS). J. C. E. acknowledges the financial support by the “FPI-MINECO” Program of MINECO (Grant BES-2015-071534).