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The fundamental model of any solid crystalline material (crystal) at the atomic scale is a periodic point set. The strongest natural equivalence of crystals is rigid motion or isometry that preserves all inter-atomic distances. Past comparisons of periodic structures often used manual thresholds, symmetry groups and reduced cells, which are discontinuous under perturbations or thermal vibrations of atoms. This work defines the infinite sequence of continuous isometry invariants (Average Minimum Distances) to progressively capture distances between neighbors. The asymptotic behaviour of the new invariants is theoretically proved in all dimensions for a wide class of sets including non-periodic. The proposed near linear time algorithm identified all different crystals in the world's largest Cambridge Structural Database within a few hours on a modest desktop. The ultra fast speed and proved continuity provide rigorous foundations to continuously parameterise the space of all periodic crystals as a high-dimensional extension of Mendeleev's table of elements.

Antibiotic stewardship programs optimize the use of antimicrobials to prevent the development of resistance and improve patient outcomes. In this prospective interventional study, a multidisciplinary team led by surgeons implemented a program aimed at shortening the duration of antibiotic treatment &lt, 7 days. The impact of the intervention on antibiotic consumption adjusted to bed-days and discharges, and the isolation of multiresistant bacteria (MRB) was also studied. Furthermore, the surgeons were surveyed regarding their beliefs and feelings about the program. Out of 1409 patients, 40.7% received antibiotic therapy. Treatment continued for over 7 days in 21.5% of cases, and, as can be expected, source control was achieved in only 48.8% of these cases. The recommendations were followed in 90.2% of cases, the most frequent being to withdraw the treatment (55.6%). During the first 16 months of the intervention, a sharp decrease in the percentage of extended treatments, with R2 = 0.111 was observed. The program was very well accepted by surgeons, and achieved a decrease in both the consumption of carbapenems and in the number of MRB isolations. Multidisciplinary stewardship teams led by surgeons seem to be well received and able to better manage antibiotic prescription in surgery.

We show that a hydrogen-bonded framework, TBAP-α, with extended π-stacked pyrene columns has a sacrificial photocatalytic hydrogen production rate of up to 3108 μmol g -1 h -1. This is the highest activity reported for a molecular organic crystal. By comparison, a chemically-identical but amorphous sample of TBAP was 20-200 times less active, depending on the reaction conditions, showing unambiguously that crystal packing in molecular crystals can dictate photocatalytic activity. Crystal structure prediction (CSP) was used to predict the solid-state structure of TBAP and other functionalised, conformationally-flexible pyrene derivatives. Specifically, we show that energy-structure-function (ESF) maps can be used to identify molecules such as TBAP that are likely to form extended π-stacked columns in the solid state. This opens up a methodology for the a priori computational design of molecular organic photocatalysts and other energy-relevant materials, such as organic electronics.

The physical properties of 3-D porous solids are defined by their molecular geometry. Hence, precise control of pore size, pore shape, and pore connectivity are needed to tailor them for specific applications. However, for porous molecular crystals, the modification of pore size by adding pore-blocking groups can also affect crystal packing in an unpredictable way. This precludes strategies adopted for isoreticular metal–organic frameworks, where addition of a small group, such as a methyl group, does not affect the basic framework topology. Here, we narrow the pore size of a cage molecule, CC3, in a systematic way by introducing methyl groups into the cage windows. Computational crystal structure prediction was used to anticipate the packing preferences of two homochiral methylated cages, CC14-R and CC15-R, and to assess the structure–energy landscape of a CC15-R/CC3-S cocrystal, designed such that both component cages could be directed to pack with a 3-D, interconnected pore structure. The experimental gas sorption properties of these three cage systems agree well with physical properties predicted by computational energy–structure–function maps., The pore size in a molecular crystal, CC3α, is narrowed by introducing methyl groups without disrupting the crystal packing, in line with energy−structure−function maps for these porous crystals.

We describe the a priori computational prediction and realization of multi-component cage pots, starting with molecular predictions based on candidate precursors through to crystal structure prediction and synthesis using robotic screening. The molecules were formed by the social self-sorting of a tri-topic aldehyde with both a tri-topic amine and di-topic amine, without using orthogonal reactivity or precursors of the same topicity. Crystal structure prediction suggested a rich polymorphic landscape, where there was an overall preference for chiral recognition to form heterochiral rather than homochiral packings, with heterochiral pairs being more likely to pack window-to-window to form two-component capsules. These crystal packing preferences were then observed in experimental crystal structures.

The energy-efficient separation of alkylaromatic compounds is a major industrial sustainability challenge. The use of selectively porous extended frameworks, such as zeolites or metal–organic frameworks, is one solution to this problem. Here, we studied a flexible molecular material, perethylated pillar[n]arene crystals (n = 5, 6), which can be used to separate C8 alkylaromatic compounds. Pillar[6]arene is shown to separate para-xylene from its structural isomers, meta-xylene and ortho-xylene, with 90% specificity in the solid state. Selectivity is an intrinsic property of the pillar[6]arene host, with the flexible pillar[6]arene cavities adapting during adsorption thus enabling preferential adsorption of para-xylene in the solid state. The flexibility of pillar[6]arene as a solid sorbent is rationalized using molecular conformer searches and crystal structure prediction (CSP) combined with comprehensive characterization by X-ray diffraction and 13C solid state NMR spectroscopy. The CSP study, which takes into account the structural variability of pillar[6]arene, breaks new ground in its own right and showcases the feasibility of applying CSP methods to understand and ultimately to predict the behaviour of soft, adaptive molecular crystals.

The adsorption and dissociation of molecular O-2 over silver extended surfaces, nanoparticles and clusters of different size, as well as the reaction between adsorbed O-2 and H-2 to form less nucleophilic hydroperoxide groups have been investigated by means of periodic DFT calculations. Hydroperoxide formation from O-2 and H-2 is in all systems kinetically favoured over O-2 dissociation, which becomes energetically forbidden on small planar clusters. The nature and reactivity towards propene of all oxygen species present on silver, including adsorbed molecular O-2, atomic O, and hydroperoxide groups, have been theoretically explored. Formation of the oxametallacycle intermediate involved in propene epoxidation is energetically accessible on subnanometric three-dimensional silver nanoparticles, but competitive pathways leading to hydrogen abstraction and allyl formation always involve lower activation barriers. Theoretical findings have been experimentally confirmed by Raman spectroscopy of O-2 adsorption and catalytic testing of planar and three dimensional silver clusters., The authors thank the Spanish Science and Innovation Ministry (MAT2011-28009, Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and Severo Ochoa) for financial support, and Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Val'ncia for computing facilities and technical assistance. A. P. thanks the Spanish Science and Innovation Ministry (Juan de la Cierva program) for her grant.

Synthetic control over pore size and pore connectivity is the crowning achievement for porous metal-organic frameworks. The same level of control has not been achieved for molecular crystals, which are not defined by strong, directional intermolecular coordination bonds. Hence, molecular crystallization is inherently less predictable than framework crystallization, and there are fewer examples of ‘reticular synthesis’, where multiple building blocks can be assembled according to a common assembly motif. Here, we apply a chiral recognition strategy to a new family of tubular covalent cages, TCC1–TCC3, to create both 1-D porous nanotubes and 3-D, diamondoid pillared porous networks in a targeted way. The diamondoid networks are analogous to metal-organic frameworks prepared from tetrahedral metal nodes and linear, difunctional organic linkers. The crystal structures can be rationalized by computational lattice energy searches, which provide an in silico screening method to evaluate candidate molecular building blocks. These results are a blueprint for applying the ‘node and strut’ principles of reticular synthesis to molecular crystals.

The sixth blind test of organic crystal structure prediction (CSP) methods has been held, with five target systems: a small nearly rigid molecule, a polymorphic former drug candidate, a chloride salt hydrate, a co-crystal and a bulky flexible molecule. This blind test has seen substantial growth in the number of participants, with the broad range of prediction methods giving a unique insight into the state of the art in the field. Significant progress has been seen in treating flexible molecules, usage of hierarchical approaches to ranking structures, the application of density-functional approximations, and the establishment of new workflows and `best practices´ for performing CSP calculations. All of the targets, apart from a single potentially disordered Z?? = 2 polymorph of the drug candidate, were predicted by at least one submission. Despite many remaining challenges, it is clear that CSP methods are becoming more applicable to a wider range of real systems, including salts, hydrates and larger flexible molecules. The results also highlight the potential for CSP calculations to complement and augment experimental studies of organic solid forms. Fil: Reilly, Anthony M.. Cambridge Crystallographic Data Centre; Fil: Cooper, Richard I.. Chemistry Research Laboratory; Fil: Adjiman, Claire S.. Imperial College London; Reino Unido Fil: Bhattacharya, Saswata. Fritz Haber Institute Of The Max Planck Society; Fil: Boese, A. Daniel. Karl-franzens-universitat Graz; Austria Fil: Brandenburg, Jan Gerit. Colegio Universitario de Londres; Reino Unido. Universitat Bonn; Alemania Fil: Bygrave, Peter J.. University of Southampton; Reino Unido Fil: Bylsma, Rita. Radboud Universiteit Nijmegen; Países Bajos Fil: Campbell, Josh E.. University of Southampton; Reino Unido Fil: Car, Roberto. University of Princeton; Estados Unidos Fil: Case, David H.. University of Southampton; Reino Unido Fil: Chadha, Renu. University Institute Of Pharmaceutical Sciences India; India Fil: Cole, Jason C.. Cambridge Crystallographic Data Centre; Fil: Cosburn, Katherine. University of Tulane; Estados Unidos. University of Toronto; Canadá Fil: Cuppen, Herma M.. Radboud Universiteit Nijmegen; Países Bajos Fil: Curtis, Farren. University of Tulane; Estados Unidos. University of Carnegie Mellon; Estados Unidos Fil: Day, Graeme M.. University of Southampton; Reino Unido Fil: DiStasio, Robert A.. University of Princeton; Estados Unidos. Cornell University; Estados Unidos Fil: Dzyabchenko, Alexander. Karpov Institute Of Physical Chemistry; Fil: Van Eijck, Bouke P.. University of Utrecht; Países Bajos. Utrecht University; Países Bajos Fil: Elking, Dennis M.. Openeye Scientific Software, Inc; Fil: Van Den Ende, Joost A.. Radboud Universiteit Nijmegen; Países Bajos Fil: Facelli, Julio C.. University of Utah; Estados Unidos Fil: Ferraro, Marta B.. Universidad de Buenos Aires; Argentina Fil: Fusti-Molnar, Laszlo. Openeye Scientific Software, Inc; Fil: Gatsiou, Christina-Anna. Imperial College London; Reino Unido Fil: Gee, Thomas S.. University of Southampton; Reino Unido Fil: De Gelder, René. Radboud Universiteit Nijmegen; Países Bajos Fil: Ghiringhelli, Luca M.. Fritz Haber Institute Of The Max Planck Society; Fil: Goto, Hitoshi. Toyohashi University Of Technology; Fil: Grimme, Stefan. Universitat Bonn; Alemania Fil: Guo, Rui. Colegio Universitario de Londres; Reino Unido Fil: Hofmann, Detlef W. M.. Flexcryst; . Polaris; Fil: Hoja, Johannes. Fritz Haber Institute Of The Max Planck Society; Fil: Hylton, Rebecca K.. Colegio Universitario de Londres; Reino Unido Fil: Iuzzolino, Luca. Colegio Universitario de Londres; Reino Unido Fil: Jankiewicz, Wojciech. University Of Silesia In Katowice; Fil: De Jong, Daniël T.. Radboud Universiteit Nijmegen; Países Bajos Fil: Kendrick, John. University Of Bradford; Fil: De Klerk, Niek J. J.. Radboud Universiteit Nijmegen; Países Bajos Fil: Ko, Hsin-Yu. University of Princeton; Estados Unidos Fil: Kuleshova, Liudmila N.. Flexcryst; Fil: Li, Xiayue. University of Tulane; Estados Unidos. Argonne National Laboratory; Estados Unidos Fil: Lohani, Sanjaya. University of Tulane; Estados Unidos Fil: Leusen, Frank J. J.. University Of Bradford; Fil: Lund, Albert M.. University of Utah; Estados Unidos. Openeye Scientific Software, Inc; Fil: Lv, Jian. Jilin University; China Fil: Ma, Yanming. Jilin University; China Fil: Marom, Noa. University of Carnegie Mellon; Estados Unidos. University of Tulane; Estados Unidos Fil: Masunov, Artëm E.. University Of Central Florida; . National Research Nuclear University Mephi; Fil: McCabe, Patrick. Cambridge Crystallographic Data Centre; Fil: McMahon, David P.. University of Southampton; Reino Unido Fil: Meekes, Hugo. Radboud Universiteit Nijmegen; Países Bajos Fil: Metz, Michael P.. University Of Delaware; Fil: Misquitta, Alston J.. Queen Mary, University Of London; Fil: Mohamed, Sharmarke. Khalifa University Of Science And Technology; Fil: Monserrat, Bartomeu. Rutgers, The State University Of New Jersey; . University of Cambridge; Estados Unidos Fil: Needs, Richard J.. University of Cambridge; Estados Unidos Fil: Neumann, Marcus A.. No especifica; Fil: Nyman, Jonas. University of Southampton; Reino Unido Fil: Obata, Shigeaki. Toyohashi University Of Technology; Fil: Oberhofer, Harald. Universitat Technical Zu Munich; Alemania Fil: Oganov, Artem R.. Northwestern Polytechnical University; China. Skolkovo Institute Of Science And Technology; . Moscow Institute Of Physics And Technology; . Stony Brook University; Fil: Orendt, Anita M.. University of Utah; Estados Unidos Fil: Pagola, Gabriel Ignacio. Universidad de Buenos Aires; Argentina Fil: Pantelides, Constantinos C.. Imperial College London; Reino Unido Fil: Pickard, Chris J.. University of Cambridge; Estados Unidos. Colegio Universitario de Londres; Reino Unido Fil: Podeszwa, Rafal. University Of Silesia In Katowice; Fil: Price, Louise S.. Colegio Universitario de Londres; Reino Unido Fil: Price, Sarah L.. Colegio Universitario de Londres; Reino Unido Fil: Pulido, Angeles. University of Southampton; Reino Unido Fil: Read, Murray G.. Cambridge Crystallographic Data Centre; Fil: Reuter, Karsten. Universitat Technical Zu Munich; Alemania Fil: Schneider, Elia. University of New York; Estados Unidos Fil: Schober, Christoph. Universitat Technical Zu Munich; Alemania Fil: Shields, Gregory P.. Cambridge Crystallographic Data Centre; Fil: Singh, Pawanpreet. University Institute Of Pharmaceutical Sciences India; India Fil: Sugden, Isaac J.. Imperial College London; Reino Unido Fil: Szalewicz, Krzysztof. University Of Delaware; Fil: Taylor, Christopher R.. University of Southampton; Reino Unido Fil: Tkatchenko, Alexandre. University Of Luxembourg; . Fritz Haber Institute Of The Max Planck Society; Fil: Tuckerman, Mark E.. University of New York; Estados Unidos. New York University Shanghai; China. Courant Institute Of Mathematical Sciences; Fil: Vacarro, Francesca. University of Tulane; Estados Unidos. Loyola University New Orleans; Fil: Vasileiadis, Manolis. Imperial College London; Reino Unido Fil: Vazquez-Mayagoitia, Alvaro. Argonne National Laboratory; Estados Unidos Fil: Vogt, Leslie. University of New York; Estados Unidos Fil: Wang, Yanchao. Jilin University; China Fil: Watson, Rona E.. Colegio Universitario de Londres; Reino Unido Fil: De Wijs, Gilles A.. Radboud Universiteit Nijmegen; Países Bajos Fil: Yang, Jack. University of Southampton; Reino Unido Fil: Zhu, Qiang. Stony Brook University; Fil: Groom, Colin R.. Cambridge Crystallographic Data Centre

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal–organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy–structure–function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy–structure–function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

[EN] The mechanism of propene epoxidation by H-2/H2O/O-2 mixtures catalyzed by gold atoms supported on defective graphene has been investigated by means of periodic density functional theory (DFT) calculations. The fact of being isolated and yet strongly bound to the support gold atoms makes formation of gold hydroperoxide H-Au-OOH intermediates from H-2 and O-2 barrierless and the subsequent reaction with propene yielding propene oxide (PO) and H2O thermodynamically and kinetically favored. The main advantage of the Au/graphene material explored in this work is not related to catalyst activity but to the selectivity toward PO that is greatly enhanced due to suppression of the main competing routes. Thus, neither propene hydrogenation yielding propane nor O-2 dissociation finally resulting in acrolein formation and/or propene combustion can compete with the desired epoxidation. The present results suggest a promising route to prepare active and highly selective gold-based catalysts for propene epoxidation, The authors thank Spanish MINECO (MAT2011-28009 and Consolider Ingenio 2010-MULTICAT, CSD2009-00050) and Generalitat Valenciana (PROMETEO/2008/130) for financial support and Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia for offering computing facilities and technical assistance. A. P. thanks Spanish MINECO (Juan de la Cierva program) for her grant.

Adsorption isotherms of carbon dioxide on the Na-A zeolite were measured in the temperature range from 273 to 333 K. Henry’s constants and isosteric adsorption heats calculated from the temperature dependence of CO2 isotherms were combined with results of the variable temperature IR spectroscopy to obtain a spectroscopic signature of adsorption complexes and corresponding thermodynamic characteristics. The adsorption of CO2 in Na-A zeolite was also investigated computationally, using a periodic density functional model improved for the proper description of dispersion interactions. Based on a good agreement between experimental and calculated adsorption heats and shifts of asymmetric CO2 stretching frequency due to adsorption the following model of CO2/Na-A system is proposed: (i) CO2 adsorption complexes formed at a low coverage involves interaction of CO2 with three Na+ cations in the LTA supercage; they are characterized by the IR band at 2349 cm−1. (ii) CO2 adsorption complexes at higher coverages are formed between a pair of Na+ cations; they are characterized by the IR band centered at 2360 cm−1. Almost half of the interaction energy between CO2 and Na-A is due to the dispersion interaction.

Since Iwamoto’s discovery of an unusually high activity of Cu/zeolites in NO decomposition, there has been an ongoing experimental and theoretical quest to understand the details of the mechanism of this process. Despite this tremendous effort, there are still a number of unsettled questions, including the uncertainty about the nature of the reaction intermediates and about the structure of the active site; either the involvement of only a single extra-framework Cu cation or the concerted effect of two nearby Cu cations, the Cu pair, was proposed. From the vast amount of relevant experimental data available today, it is clear that the activity of the Cu/zeolite catalysts depends on 1) zeolite topology, 2) zeolite composition (Si/Al ratio and Cu loading), and 3) Cu-exchange procedure, including the sample pretreatment. 6,8, 12, 13,15] However, the understanding of the relationship between active site structure (the metal coordination and localization) and catalytic activity is far from complete; it is our goal to increase our knowledge in this respect. The lack of direct experimental evidence about the transition-state structures and about the details of the reaction mechanism justifies the use of quantum chemistry to provide the missing details. However, a reliable description of the reactions catalyzed by transition metals in a complex environment (such as zeolites) represents a major challenge for contemporary computational chemistry since it requires the use of a model that realistically represents the active site (including its environment) and the use of a method that can consistently describe the electronic structure of the system along the reaction path (see the Methods section). Many reaction steps possibly involved in the direct NO decomposition on Cu/zeolites have been investigated previously by employing various models and methods. Several reaction paths proposed in the literature have been compiled (Scheme 1) along with the reaction energies and activation barriers (where available) reported for the elementary reaction steps. Since these energies were obtained at various levels of theory using different types of models for the active site, a direct comparison should be taken with some caution. For example, the reaction energies of 107 and 173 kJmol 1 were reported for reaction step D based on the BP86 functional (using a 1-T cluster model) and based on the B3LYP functional (using a 3-T cluster model), respectively. A majority of the proposed reaction mechanisms start with the interaction of two NO molecules with Cu/zeolite (ZCu) producing ZCuO and N2O (A!B!C). Different routes were proposed for the subsequent conversion of N2O: 1) it can interact with another NO molecule to produce N2 and NO2. One of the G!I!J, A!K!L, or M!L routes can be followed; the rate-determining steps of these reaction routes are characterized with activation barriers of 105, 122, and 126 kJmol 1[20] , respectively. 2) N2O can be reattached to ZCu to release N2 while forming another ZCuO species (process G!H). Note however, that all these reaction paths lead to the production of NO2 and/or ZCuO species. To close the catalytic cycle, the ZCuO needs to be reduced back to ZCu and the NO2 must further react. However, NO2 can readily interact with ZCuO forming ZCuNO3 (process O; DE= 252 kJmol ). It is not clear how to proceed from a stable ZCuNO3 complex towards the products. Another route was proposed following the A!B!C path: a simple reaction mechanism based on the readsorption of N2O on ZCuO (through the O-end) that leads to the formation of N2, O2, and ZCu (D!E!F). An activation barrier for the rate-determining step on this path (the formation of ZCuO2N2) of 152 and 145 kJmol 1 has been reported based on BP86/(1-T cluster) and B3LYP/(3-T cluster) calculations, respectively. Whereas the activation barrier of the D!E!F Scheme 1. A schematic representation of the possible processes taking place during NO removal in zeolites. The reaction energies and activation barriers (denoted by #) are taken from the literature: a) Ref [16] , b) Ref. [17] , c) Ref. [18] , d) Ref. [19] , and e) Ref. [20] . Superscript numbers refer to the spin multiplicity of the adsorption complex.

A combination of variable-temperature Fourier transform infrared (FTIR) spectroscopy with calculations performed at the periodic density functional theory (DFT) level was used in the investigation of carbon monoxide adsorption on zeolites Na-ZSM-5 and K-ZSM-5. On the basis of a very good agreement between experimental and calculated frequencies and adsorption enthalpies, it is shown that the IR absorption band appearing in the intermediate frequency range for adsorbed CO (2155 and 2150 cm-1 for Na-ZSM-5 and K-ZSM-5, respectively) is due to the formation of linearly bridged CO adsorption complexes on dual-cation sites (M+···CO···M+, M = Na, K). The population of such adsorption complexes increases with increasing cation radius and with decreasing Si/Al ratio. Bridged adsorption complexes are slightly more stable than carbonyl complexes formed on isolated extraframework metal cations. Adsorption enthalpies and CO stretching frequencies of carbonyl complexes formed on isolated extraframework metal cations we...

[EN] The kinetics of the ketonic decarboxylation of linear and branched carboxylic acids over m-ZrO2 as a catalyst has been investigated. The same apparent activation energy is experimentally determined for the ketonic decarboxylation of both linear pentanoic and branched 2-methyl butanoic acids, while the change in entropy for the rate-determining step differs by nearly 50 kJ mol(-1). These results show that the difference in reactivity between linear and branched acids is due to entropic effects, and is related to the probability of finding the reactant molecules adsorbed and activated in a suitable way on the catalyst surface., The authors thank MINECO (Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and Severo Ochoa program, SEV-2012-0267), Generalitat Valenciana (PROMETEOII/2013/011 Project), and the Spanish National Research Council (CSIC, Es 2010RU0108) for financial support. Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational facilities and technical assistance. A. P., F. G. and B. O.-T. thank MINECO (Juan de la Cierva and FPU Programme) and CSIC (JAE Programme) for their fellowships, respectively. M. R. is grateful to the Generalitat Valenciana for a BEST 2015 fellowship.

The distribution of fluoride ions has been studied in the pure silica IFR, ITH, IWR, STF and STT zeolite structures using computational techniques. The interactions between the F- and SDA+ ions (where SDA is the organic structure directing agent) are able to explain the F- cage occupation found experimentally. While studying the short-range fluoride-framework interactions, a relationship was found between the Si atoms forming the pentacoordinated units and the lowest F- defect energies, which rationalizes the experimental Si-F bonding in terms of energetic stability. It is proposed that the F- location is governed by a two step process. In a first stage, the electrostatic long-range forces and, especially, the interactions between the F- and the SDA+ ions, decide which cage will be filled with F-; in a second stage, once the F- cage location is decided, the F- forms a covalent bond with a Si site to form an energetically stable pentacoordinated unit [SiO4/2F]-.

Computational chemistry is used here to rationalize zeolite nucleation and crystallization by means of atomistic molecular mechanic techniques. It is shown that, by isomorphous substitution of Ge by Si, the relative rate of crystallization can be reversed in a series of zeolite structures that compete to nucleate and grow under certain synthesis conditions. This is demonstrated for EU-1, ITQ-13, ITQ-22, and ITQ-24 structures.

[EN] The preferential crystallization of pure silica ITQ-39 and MFI zeolites using SDAEt and SDAPr, respectively, as organic structure directing agents (SDAs) is investigated here by theoretical methods using a periodic DFT-D model. For this purpose, the templating roles of SDAEt and SDAPr have been analyzed following a systematic study of the interaction of these two SDAs with the previously described zeolites through SDA stabilization energies (balance of intermolecular SDA dispersive interactions and SDA strain). From theoretical studies, it has been found that SDAEt located inside ITQ-39 zeolite and SDAPr placed within MFI show the largest stabilizations. These theoretical results agree with previous experimental observations for the preferential crystallization of pure silica ITQ-39 and MFI using SDAEt and SDAPr molecules, respectively., Financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267), Consolider Ingenio 2010-Multicat, MAT2012-37160 and, Intramural-201480I015 is acknowledged.

The ketonic decarboxylation of carboxylic acids has been carried out experimentally and studied theoretically by DFT calculations. In the experiments, monoclinic zirconia was identified as a good catalyst, giving high activity and high selectivity when compared with other potential catalysts, such as silica, alumina, or ceria. It was also shown that it could be used for a wide range of substrates, namely, for carboxylic acids with two to eighteen carbon atoms. The reaction mechanism for the ketonic decarboxylation of acetic acid over monoclinic zirconia was investigated by using a periodic DFT slab model. A reaction pathway with the formation of a β-keto acid intermediate was considered, as well as a concerted mechanism, involving simultaneous carbon-carbon bond formation and carbon dioxide elimination. DFT results showed that the mechanism with the β-keto acid was the kinetically favored one and this was further supported by an experiment employing a mixture of isomeric (linear and branched) pentanoic acids. This way or that? Monoclinic zirconia has great potential as a catalyst for ketonic decarboxylation of carboxylic acids (see picture). A combined experimental and DFT study shows a route involving a β-keto acid intermediate as the kinetically preferred reaction pathway., We thank MINECO (MAT2011-28009, Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and CTQ2011-27550) and the Spanish National Research Council (CSIC, Es 2010RU0108) for funding. Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are acknowledged for computational facilities and technical assistance. A. P. and B.O.-T. thank MINECO (Juan de la Cierva Programme) and CSIC (JAE Programme), respectively, for their fellowships.

[EN] Low-temperature (-176 degrees C) CO adsorption on graphene oxide and partially reduced graphene oxide sheets was investigated in a combined IR spectroscopic and DFT study. The reactivity of the carbon vacancies in the network was observed to be extremely high, causing the CO molecules to dissociate in a barrier-less process that leads to the reconstruction of the sp(2) graphene network. After the adsorption of CO on the graphene oxide materials, the intensity of the FTIR bands is lower in the case of partially reduced graphene oxide sheets, indicating that there are fewer active sites available for CO interaction., The authors thank the Spanish Science and Innovation Ministry (Consolider Ingenio 2010, Project MULTICAT, ref. CSD2009-00050) for their financial support, and Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia for offering computing facilities and technical assistance. P. A. and A. P. thank the Spanish Science and Innovation Ministry (Ramon y Cajal and Juan de la Cierva programs) and C. B. thanks FICYT for their grants. Special thanks to Pablo Ares from Nanotec Electronica (TM) for AFM contribution.

[EN] The structure and stabilization of a series of gold (Au-n) clusters (where n = 1, 5, 6, 19 and 39) supported on the perfect and defective (vacancy and/or N-doped) graphene sheets were investigated using a periodic DFT model. Much stronger interaction was found between a gold atom and the graphene sheet with a defective structure that is comparable to interaction energies reported for different transition metal oxide supports. Increasing gold particle size does not weaken the interaction with the single vacancy graphene sheet, where the gold clusters are anchored to the carbon surface through only one gold atom and the cluster shape is preserved. Catalytic performance of Au(100) facets in the isolated and graphene-supported Au-39 nanoparticle (mean size similar to 1 nm) for the O-2 dissociation reaction was investigated. Structure of the involved species along the reaction pathway and energy profile were found very much alike, regardless the reaction takes place on the isolated or graphene-supported gold nanoparticle., The authors thank CICYT (MAT 2006-14274-C02-01), Consolider-Ingenio-2010 (project MULTICAT) for financial support, and Red Espan˜ola de Supercomputacio´n (RES) and Centre de Ca`lcul de la Universitat de Vale`ncia for computational resources and technical assistance.

Carbon monoxide is frequently used as a probe molecule for characterization of adsorption sites in zeolites by means of infrared (IR) spectroscopy. IR spectra of carbonyl species in zeolites are usually understood within a concept of CO adsorption on a single cation site. This concept, however, is not sufficient in microporous materials when the concentration of cationic sites increases. Adsorption complexes formed on homogeneous dual cation sites were recently described (J. Phys. Chem. B 2006, 110, 22542) based on a combination of experimental and theoretical investigations. The concept of dual cation sites is extended for the situation where CO is strongly bound on the Cu+ cation and it also interacts with the extra-framework alkali-metal cation. The existence and properties of theCOadsorption complexes on such heterogeneous dual cation sites are discussed for Cu,M-FER zeolites (M =H, Na, K, Cs) having various compositions. Based on a good agreement between theoretical (periodic density functional theory) and experimental (IR, microcalorimetry, TPD) results, the interpretation of some IR features is offered.

[EN] Adsorption of H(2) on the zeolite Ca-A was investigated by a combination of variable temperature IR spectroscopy and calculations at the periodic DFT level. Calculations showed that adsorption complexes can be formed on two types of adsorption sites: Ca(2+) in the center of six-member rings and Ca(2+) in eight-member rings. Only the former adsorption complexes were experimentally observed in IR spectra; they are characterized by H-H stretching frequency of 4083 cm (1) and Delta H(0) = -12 kJ/mol in agreement with calculated results. The most likely explanation for not observing the adsorption complex on Ca(2+) in 8-member rings is that the geometry of the complex does not render the H-H stretching mode IR active. (C) 2009 Published by Elsevier B. V., Work in Prague was supported by research projects 203/09/0143 (GA C. R), MSM0021620857 and LC512 (MSMT C. R). AP acknowledges the support from Spanish MICINN (post-doctoral fellowship). The Spanish MICINN and FEDER funds are gratefully acknowledged for financial support to the work done at the UIB (Projects MAT2008-00089 and PCI2006-A7-0618). The access to the META Centrum computing facilities provided under the research intent MSM6383917201 is acknowledged.

Interaction of the CO molecule with CuX-FER zeolites (X is an alkali-metal or proton as a co-cation) was investigated by IR spectroscopy and DFT calculations. An absorption band at 2138 cm −1 observed in IR spectra of CO on CuK- and CuCs-FER zeolites was assigned to a new type of CO adsorption complex on heterogeneous dual cation sites. CO molecule interacts simultaneously with Cu + and alkali metal cations (via C- and O-end, respectively) in this type of complex. Interaction of CO with the secondary (alkali metal) cation led to a slight destabilization of the carbonyl complex.

(19)F NMR chemical shifts are calculated in order to study the F(-) environment in double four ring (D4R) containing Si/Ge-zeolites. The calculations with the DFT/CSGT/B3PW91 methodology yielded an agreement within 2 ppm with respect to the experimental peaks corresponding to the D4R units containing 8Si0Ge, 7Si1Ge and 0Si8Ge of the octadecasil zeolite. The optimisation of the 7Si1Ge-, 6Si2Ge-, 5Si3Ge- and 4Si4Ge-D4R units with DFT/B3LYP methodology shows that a covalent Ge-F bond is formed and therefore a Ge atom in the D4R is pentacoordinated. The displacement of the fluoride ion towards a Ge atom in the Ge-containing D4R units locates four Si/Ge atoms in the close vicinity of the F(-) and this makes possible a rationalization of the (19)F NMR signals in groups according to the number of Si (n) and Ge (m) atoms in the nearest F(-) environment, F-Si(n)Ge(m) (where n+m=4). Thus, the calculated chemical shifts show that higher values are observed when the number of Ge atoms in the nearest F(-) environment increases.

Among microporous materials, there has been an increasing recent interest in porous organic cage (POC) crystals, which can display permanent intrinsic (molecular) and extrinsic (crystal network) porosity. These materials can be used as molecular sieves for gas separation and potential applications as enzyme mimics have been suggested since they exhibit structural response toward guest molecules[1]. Small structural modifications of the initial building blocks of the porous organic molecules can lead to quite different molecular assembly[1]. Moreover, the crystal packing of POCs is based on weak molecular interactions and is less predictable that other porous materials such as MOFs or zeolites.[2] In this contribution, we show that computational techniques -molecular conformational searches and crystal structure prediction- can be successfully used to understand POC crystal packing preferences. Computational results will be presented for a series of closely related tetrahedral imine- and amine-linked porous molecules, formed by [4+6] condensation of aromatic aldehydes and cyclohexyl linked diamines. While the basic cage is known to have one strongly preferred crystal structure, the presence of small alkyl groups on the POC modifies its crystal packing preferences, leading to extensive polymorphism. Calculations were able to successfully identify these trends as well as to predict the structures obtained experimentally, demonstrating the potential for computational pre-screening in the design of POCs within targeted crystal structures. Moreover, the need of accurate molecular (ab initio calculations) and crystal (based on atom-atom potential lattice energy minimization) modelling for computer-guided crystal engineering will be discussed.

The adsorption of CO(2) in Li-, Na-, and K-FER was investigated by a combination of volumetric adsorption experiments, FTIR spectroscopy, and density functional theory. Experimental isosteric heats of CO(2), Q(st), depend significantly on the cation size, cation concentration, and on the amount of adsorbed CO(2). The differences observed in experimentally determined isosteric heats were interpreted at the molecular level based on good agreement between experimental and calculated characteristics. The highest interaction energies were found for CO(2) adsorbed on so-called "dual cation sites" in which CO(2) is bridged between two alkali metal cations. The formation of CO(2) adsorption complexes on dual cation sites is particularly important on Na-FER and K-FER samples with higher cation concentration. On the contrary, the differences in Q(st) observed for Li-FER samples are due to the changes in the Li(+) coordination with the framework. The DFT/CC calculations show that the dispersion interactions between CO(2) and the zeolites framework are rather large (about -20 kJ mol(-1)).

Periodic DFT calculations were performed on H-FER models having Si/Al ratios of 71 : 1, 35 : 1 and 8 : 1, in order to investigate the effect of aluminium content on the properties of the zeolite Brønsted acid sites. Relative stability of these sites was found to be dependent on Si/Al ratio, which is the main factor dictating the relative concentration of Brønsted acid sites having different types of local configuration, to the point that some types of acid site are formed only when the aluminium content of the zeolite is relatively high. The number of AlO(4) tetrahedra sharing an oxygen with the SiO(4) tetrahedron involved in the Brønsted acid site determines the Si-O(H)-Al angle, O-H stretching frequency and deprotonation energy (and hence acid strength). For Brønsted acid protons not involved in intra-zeolite H-bonding, a correlation was found between Si-O(H)-Al angle and O-H stretching frequency.

The structure and stability of nitrosyl complexes formed in Cu-FER zeolite were investigated using a periodic DFT model. The reliability of both DFT methods and cluster models when describing the Cu(+) interaction with NO molecules was examined. The relative stabilities of mononitrosyl complexes on various Cu(+) sites in Cu-FER are governed by the deformation energy of the particular site. Three types of dinitrosyl complexes with different coordination on the Cu(+) cation were identified: (i) four-fold tetrahedral, (ii) four-fold square-planar and (iii) three-fold trigonal-planar complexes. The most stable dinitrosyl complex, formed when the two NO molecules interact with Cu(+)via the N atom, has a tetrahedral coordination on Cu(+). The cyclic adsorption complex, having a square-planar arrangement of ligands on Cu(+) and interaction via O atoms, is only about 10 kJ mol(-1) less stable than the N-down dinitrosyl complex. This cyclic dinitrosyl complex is suggested to be the key intermediate in the deNO(x) process taking place in Cu-zeolites.

Adsorption of carbon dioxide on H-FER zeolite (Si:Al = 8:1) was investigated by means of a combined methodology involving variable-temperature infrared spectroscopy and DFT/CC calculations on periodic zeolite models. The experimentally found value of adsorption enthalpy was ΔH0 = −30 kJ mol−1. According to calculations, adsorption complexes on isolated Si(OH)Al Bronsted acid sites (single sites) involve an adsorption enthalpy in the range of −33 to −36 kJ mol−1, about half of which is due to weak intermolecular interactions between CO2 and the zeolite framework. Calculations show clearly the significant role played by weak intermolecular interactions; adsorption enthalpies calculated with standard GGA type exchange-correlation functionals are about 13 kJ mol−1 underestimated with respect to experimental results. Good agreement was also found between calculated and experimentally observed stretching frequencies for these complexes. Calculations revealed that CO2 adsorption complexes involving two neighbouring Bronsted acid sites (dual sites) can be formed, provided that the dual site has the required geometry. However, no clear evidence of CO2 adsorption complexes on dual sites was experimentally found.