Articles de revues : « CO molecules »

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Sun, Zhong-Fa, Marc C. van Hemert, Jérôme Loreau, Ad van der Avoird, Arthur G. Suits et David H. Parker. « Molecular square dancing in CO-CO collisions ». Science 369, n^o 6501 (16 juillet 2020) : 307–9. http://dx.doi.org/10.1126/science.aan2729.

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Knowledge of rotational energy transfer (RET) involving carbon monoxide (CO) molecules is crucial for the interpretation of astrophysical data. As of now, our nearly perfect understanding of atom-molecule scattering shows that RET usually occurs by only a simple “bump” between partners. To advance molecular dynamics to the next step in complexity, we studied molecule-molecule scattering in great detail for collision between two CO molecules. Using advanced imaging methods and quasi-classical and fully quantum theory, we found that a synchronous movement can occur during CO-CO collisions, whereby a bump is followed by a move similar to a “do-si-do” in square dancing. This resulted in little angular deflection but high RET to both partners, a very unusual combination. The associated conditions suggest that this process can occur in other molecule-molecule systems.

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Magrashi, Maryam Ali, et Elham Shafik Aazam. « The co-crystal 4,6-diacetylresorcinol–1-aminopyrene (2/1) ». Acta Crystallographica Section E Crystallographic Communications 78, n^o 6 (31 mai 2022) : 679–81. http://dx.doi.org/10.1107/s2056989022005588.

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The structure of the title molecular complex, C16H11N·2C10H10O4, at 150 K has been determined. The molecules form stacks consisting of aggregates with disordered 1-aminopyrene molecule surrounded by two 4,6-diacetylresorcinol molecules. Neighbouring stacks are linked by hydrogen bonds between the amine H atoms of the 1-aminopyrene molecule with the adjacent carbonyl oxygen atom of the 4,6-diacetylresorcinol molecule.

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Birajdar, SS, JW Gaikwad et DB Suryawanshi. « Microwave assisted co-operative dynamics and structural variations in chlorobenzene-acetonitrile solutions ». Bangladesh Journal of Scientific and Industrial Research 57, n^o 2 (26 juin 2022) : 85–90. http://dx.doi.org/10.3329/bjsir.v57i2.60404.

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Molecular interactions between CBZ-ACN at 8.845 GHz of microwave frequency region confer structural behavior of molecules such that either monomers or multimers are present in the agreed binary mixtures. Effect of microwave frequency on molecular interactions and hydrogen bonding between C≡N (nitrile) molecule and Cl (chlorine) molecule of CBZ and ACN binary solutions has been studied using X-band microwave technique at 301ºK. Co-operative dynamics and hydrogen bonding between nitrile and chlorine group molecules has been thoroughly explicated thereby obtaining static dielectric constant, excess permittivity, Kirkwood correlation factor using Luzar model and Bruggeman factor. Bangladesh J. Sci. Ind. Res. 57(2), 85-90, 2022

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Lu, Xiaofeng, Jibin Sun, Shangxi Zhang, Longfei Ma, Lei Liu, Hui Qi, Yongliang Shao et Xiangfeng Shao. « Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes ». Beilstein Journal of Organic Chemistry 11 (19 juin 2015) : 1043–51. http://dx.doi.org/10.3762/bjoc.11.117.

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A series of donor–acceptor type co-crystals of fullerene (as the acceptor) and arylthio-substituted tetrathiafulvalene derivatives (Ar-S-TTF, as the donor) were prepared and their structural features were thoroughly investigated. The formation of co-crystals relies on the flexibility of Ar-S-TTF and the size matches between Ar-S-TTF and fullerene. Regarding their compositions, the studied co-crystals can be divided into two types, where types I and II have donor:acceptor ratios of 1:1 and 1:2, respectively. Multiple intermolecular interactions are observed between the donor and acceptor, which act to stabilize the structures of the resulting co-crystals. In the type I co-crystals, the fullerene molecule is surrounded by four Ar-S-TTF molecules, that is, two Ar-S-TTF molecules form a sandwich structure with one fullerene molecule and the other two Ar-S-TTF molecules interact with the fullerene molecule along their lateral axes. In the type II co-crystals, one fullerene molecule has the donor–acceptor mode similar to that in type I, whereas the other fullerene molecule is substantially surrounded by the aryl groups on Ar-S-TTF molecules and the solvent molecules.

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Rivera, Augusto, John Sadat-Bernal, Jaime Ríos-Motta et Michael Bolte. « Co-Crystal with Unusual High Z′ and Z′′ Values Derived from Hexamethylenetetramine and 4-fluorophenol (1/1) ». Crystals 9, n^o 10 (10 octobre 2019) : 520. http://dx.doi.org/10.3390/cryst9100520.

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The title co-crystal, 1,3,5,7-tetraazatricyclo[3.3.1.13,7]decane (HMTA, 1)–4-fluorophenol (4-FP) (1/1), C6H12N4·C6H5FO, shows an unusual asymmetric unit that comprises eight independent molecules (Z′′ = 8), four for each component, with four formula units per asymmetric unit (Z′ = 4). In the molecular packing, each HMTA molecule bridges one 4-FP molecule via an O−H···N hydrogen bond to form a two-molecule aggregate. Differences can be observed between the bond lengths and angles of the independent HMTA and 4-FP molecules and those of the molecules in the aggregate. The C−N bonds exhibit different bond lengths in the tetrahedral cage-like structure of the HMTA molecules, but the largest differences between the molecular aggregates are in the bond lengths in the 4-fluorophenol ring. In the crystal, the HMTA and 4-FP molecules form two hydrogen-bonded (O−H···N, C−H···F and C−H···O) dimers of HMTA and 4-FP molecules, A···D and B···C inversion dimers, which generate enlarged R88(34) ring motifs in both supramolecular structures. In both structures, the crystal packing also features additional C−H···F and C−H···O interactions. The A···D and B···C dimers are linked by additional C−H···F and C−H···O hydrogen bonds, forming columns along the a and b axes, respectively. The importance of the C−H···F interaction to the structure and crystal packing has been demonstrated.

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Davoodian, Negin, et Zahra Khoshbin. « Adsorption and diffusion of H2 and CO on UiO-66 : A Monte Carlo simulation study ». European Journal of Chemistry 11, n^o 3 (30 septembre 2020) : 217–22. http://dx.doi.org/10.5155/eurjchem.11.3.217-222.2008.

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Metal-organic frameworks (MOFs) are a new class of nanoporous materials that have attracted much attention for the adsorption of small molecules, due to the large size of the cavities. In this study, we investigate the adsorption and diffusion of hydrogen (H2) and carbon monoxide (CO) guest molecules to the UiO-66 framework, as one of the most widely used MOFs, by using Monte Carlo simulation method. The results prove that an increment in the temperature decreases the amount of the adsorbed H2 and CO on the UiO-66 framework. While an enhancement of the pressure increases the amount of the adsorbed H2 and CO on the UiO-66 framework. Besides, the adsorption of H2 and CO on UiO-66 is the type I isotherm. The calculated isosteric heat for CO/UiO-66 is slightly higher than that of H2/UiO-66. The means of square displacement (MSD) value is less for CO molecule; hence, the movement of the guest molecule within the host cavity slows down and the guest molecule travels a shorter distance over a period of time. The guest molecule with higher molecular mass possesses less mobility, and therefore, it will have less permeability.

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Zobi, Fabio. « CO and CO-releasing molecules in medicinal chemistry ». Future Medicinal Chemistry 5, n^o 2 (février 2013) : 175–88. http://dx.doi.org/10.4155/fmc.12.196.

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Weng, Ze F., W. D. Sam Motherwell, Frank H. Allen et Jacqueline M. Cole. « Conformational variability of molecules in different crystal environments : a database study ». Acta Crystallographica Section B Structural Science 64, n^o 3 (15 mai 2008) : 348–62. http://dx.doi.org/10.1107/s0108768108005442.

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A methodology is described for analysing the Cambridge Structural Database (CSD) in terms of molecular conformations. Molecular species that have more than a single occurrence across the complete CSD are identified, either as the sole crystal component or co-crystallized with other components. Cluster analysis, based on a root-mean-square fit of coordinates and chemical connectivity, is performed to identify conformational variance for each molecule. Results are analysed in terms of the number of discrete conformations observed versus the number of crystal environments and number of acyclic torsion angles in the molecule. Special subsets of environments are also analysed, namely polymorphs, co-crystals and solvates. In general, conformational diversity increases with an increasing number of different crystal environments and with an increasing number of flexible torsion angles. Overall, molecules with one or more acyclic flexible torsion angle are observed to exist in more than one conformation in ca 40% of cases. There is evidence that solvated molecules exhibit more conformational flexibility on average, compared with polymorphs and co-crystals.

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Fan, Yan, et Zhi-Rong Qu. « Crystal structure of bis[2-(1H-benzimidazol-2-yl)-4-bromophenolato-κ2N3,O]cobalt(II) ». Acta Crystallographica Section E Structure Reports Online 70, n^o 11 (11 octobre 2014) : m363—m364. http://dx.doi.org/10.1107/s1600536814021813.

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The asymmetric unit of the title CoIIcomplex, [Co(C13H8BrN2O)2], contains two independent molecules (AandB). In both molecules, the CoIIcation isN,O-chelated by two 2-(1H-benzimidazol-2-yl)-4-bromophenolate anions in a distorted tetrahedral geometry. In moleculeA, both chelating rings display an envelope conformation, with the flap Co atom lying 0.614 (6) and 0.483 (6) Å from the mean planes of the remaining atoms. In moleculeB, both chelating rings are approximately planar, the maximum deviations being 0.039 (4) and 0.076 (3) Å. In the crystal, molecules are linked by classical N—H...O hydrogen bonds and weak C—H...O and C—H...Br hydrogen bonds into a three-dimensional supramolecular network. Extensive π–π stacking is observed between nearly parallel aromatic rings of adjacent molecules with centroid–centroid distances in the range 3.407 (3)–3.850 (4) Å.

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Carballo, Rosa, Emilia García-Martínez, Gumersindo Pereiras-Gabián et Ezequiel M. Vázquez-López. « Note : Synthesis of the Dinuclear Halogeno-Bridged Complexes [Re2(μ-X)2(CO)6(CH3CN)2], (X = Cl, Br) ». Zeitschrift für Naturforschung B 58, n^o 10 (1 octobre 2003) : 1021–23. http://dx.doi.org/10.1515/znb-2003-1014.

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Complexes [Re2(μ-X)2(CO)6(NCCH3)2] (X = Cl, Br) have been easily prepared in high yield by refluxing of fac- [ReX(CO)3(NCCH3)2] in toluene. The crystal and molecular structure of the bromine derivative have been determined by X-ray analysis. The molecule consists of two fac-Re(CO)3 fragments bridged by two bromine atoms. The acetonitrile molecules reside above and below the Re2Br2 plane.

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Sylvester, Eric, Mitchell McGovern, An Young Lee, Phanxico Nguyen, Jungeun Park et Jason B. Benedict. « Partial charge transfer in the salt co-crystal of L-ascorbic acid and 4,4′-bipyridine ». Acta Crystallographica Section E Crystallographic Communications 75, n^o 6 (3 mai 2019) : 728–31. http://dx.doi.org/10.1107/s2056989019005334.

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In the title 1:2 co-crystal, C10H9N2 +·(C6H7.75O6·C6H7.25O6)−, L-ascorbic acid (LAA) and 4,4′-bipyridine (BPy) co-crystallize in the chiral space group P21 with two molecules of LAA, and one molecule of bpy in the asymmetric unit. The structure was modeled in two parts due to possible proton transfer from LAA to the corresponding side of the bpy molecule having an occupancy of approximately 0.25 and part 2 with an occupancy of approximately 0.75. In this structure, LAA forms hydrogen bonds with neighboring LAA molecules, forming extended sheets of LAA molecules which are bridged by bpy molecules. A comparison to a related and previously published co-crystal of LAA and 3-bromo-4-pyridone is presented.

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Babu, D., R. Motterlini et R. A. Lefebvre. « CO and CO-releasing molecules (CO-RMs) in acute gastrointestinal inflammation ». British Journal of Pharmacology 172, n^o 6 (2 juillet 2014) : 1557–73. http://dx.doi.org/10.1111/bph.12632.

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Xiang, Feifei, Tobias Schmitt, Marco Raschmann et M. Alexander Schneider. « Adsorption and self-assembly of porphyrins on ultrathin CoO films on Ir(100) ». Beilstein Journal of Nanotechnology 11 (5 octobre 2020) : 1516–24. http://dx.doi.org/10.3762/bjnano.11.134.

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Porphyrins represent a versatile class of molecules, the adsorption behavior of which on solid surfaces is of fundamental interest due to a variety of potential applications. We investigate here the molecule–molecule and molecule–substrate interaction of Co-5,15-diphenylporphyrin (Co-DPP) and 2H-tetrakis(p-cyanophenyl)porphyrin (2H-TCNP) on one bilayer (1BL) and two bilayer (2BL) thick cobalt oxide films on Ir(100) by scanning tunneling microscopy (STM) and density functional theory (DFT). The two substrates differ greatly with respect to their structural and potential-energy landscape corrugation with immediate consequences for adsorption and self-assembly of the molecules studied. On both films, an effective electronic decoupling from the metal substrate is achieved. However, on the 1BL film, Co-DPP molecules are sufficiently mobile at 300 K and coalesce to self-assembled molecular islands when cooled to 80 K despite their rather weak intermolecular interaction. In contrast, on the 2BL film, due to the rather flat potential landscape, molecular rotation is thermally activated, which effectively prevents self-assembly. The situation is different for 2H-TCNPP, which, due to the additional functional anchoring groups, does not self-assemble on the 1BL film but forms self-assembled compact islands on the 2BL film. The findings demonstrate the guiding effect of the cobalt oxide films of different thickness and the effect of functional surface anchoring.

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Kumar, Anmol, et Shridhar R. Gadre. « Molecular Electrostatic Potential-Based Atoms in Molecules : Shielding Effects and Reactivity Patterns ». Australian Journal of Chemistry 69, n^o 9 (2016) : 975. http://dx.doi.org/10.1071/ch16226.

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The Atoms in Molecules (AIM) concept based on the zero-flux surface (ZFS) of the gradient of molecular electrostatic potential (MESP) has been recently proposed by the present authors. The nature of MESP-based atomic basins brings out the asymmetric electronic distribution in a molecule. An electron-rich atom among the two bonded atoms is seen to possess a completely closed MESP-based atomic basin. The present article illustrates the nature of atomic basins for a variety of molecules such as BF, BH3, AlCl3, B2H6, and Al2Cl6, and a Lewis acid–base pair, viz. NH3BH3 wherein the electronic distribution is not merely guided by difference in the electronegativity of the atoms. The study also explores some transition metal complexes, viz. Ni(CO)4, Fe(CO)5, Cr(CO)6, Mn2(CO)10, Co2(CO)8, Fe(η5-C5H5)2, Co(η3-C3H5), and Co(η3-C3H5)(CO)3, which show a similar phenomenon of intricate charge transfer among the ligands and the metal centre. The present article employs MESP-based AIM for a qualitative explanation of the shielding or deshielding effects revealed by NMR data as well as susceptibility of an atomic region towards an electrophilic or nucleophilic attack. Because the topographical features of MESP and thus the nature of atomic basins are not very sensitive to the level of theory and basis set, the present article demonstrates the capability of MESP as a consistent and simple tool for the portrayal of asymmetry in molecular charge distribution.

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Paul, Rima, et Sanchay Jyoti Bora. « Redetermined structure of 4,4′-bipyridine–1,4-phenylenediacetic acid (1/1) co-crystal ». Acta Crystallographica Section E Crystallographic Communications 71, n^o 10 (26 septembre 2015) : o799—o800. http://dx.doi.org/10.1107/s2056989015017569.

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The asymmetric unit of the title 1:1 co-crystal, C10H8N2·C10H10O4, consists of one half-molecule each of 4,4′-bipyridine and 1,4-phenylenediacetic acid: the complete molecules are generated by crystallographic inversion centres. The dihedral angle between the –CO2H group and the benzene ring in the diacid is 73.02 (7)°. In the crystal, the components are linked by O—H...N hydrogen bonds, generating [1-2-1] chains of alternating amine and carboxylic acid molecules. The chains are cross-linked by C—H...O interactions. This structure was previously incorrectly described as a (C10H10N2)2+·(C10H8O4)2−molecular salt [Jiaet al.(2009).Acta Cryst.E65, o2490–o2490].

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Liljegren, S., A. Jerkstrand et J. Grumer. « Carbon monoxide formation and cooling in supernovae ». Astronomy & ; Astrophysics 642 (octobre 2020) : A135. http://dx.doi.org/10.1051/0004-6361/202038116.

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Context. The inclusion of molecular physics is an important piece that tends to be missing from the puzzle when modeling the spectra of supernovae (SNe). Molecules have both a direct impact on the spectra, particularly in the infrared, and an indirect one as a result of their influence on certain physical conditions, such as temperature. Aims. In this paper, we aim to investigate molecular formation and non-local thermodynamic equilibrium (NLTE) cooling, with a particular focus on CO, the most commonly detected molecule in supernovae. We also aim to determine the dependency of supernova chemistry on physical parameters and the relative sensitivity to rate uncertainties. Methods. We implemented a chemical kinetic description of the destruction and formation of molecules into the SN spectral synthesis code SUMO. In addition, selected molecules were coupled into the full NLTE level population framework and, thus, we incorporated molecular NLTE cooling into the temperature equation. We produced a test model of the CO formation in SN 1987A between 150 and 600 days and investigated the sensitivity of the resulting molecular masses to the input parameters. Results. We find that there is a close inter-dependency between the thermal evolution and the amount of CO formed, mainly through an important temperature-sensitive CO destruction process with O+. After a few hundred days, CO completely dominates the cooling of the oxygen-carbon zone of the supernova which, therefore, contributes little optical emission. The uncertainty of the calculated CO mass scales approximately linearly with the typical uncertainty factor for individual rates. We demonstrate how molecular masses can potentially be used to constrain various physical parameters of the supernova.

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Imani, Khadije, Gholamhossein Jafari et Mohammad Reza Abolhasani. « Electronic Structure Calculation of Adsorbate Gas Molecules on an Armchair Graphene Nanoribbon ». ISRN Condensed Matter Physics 2012 (5 novembre 2012) : 1–5. http://dx.doi.org/10.5402/2012/368634.

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By using the first-principle methods, we have investigated the adsorption of the CO, CO2, NO, and NH3 molecules on an armchair graphene nanoribbon (AGNR). The optimal adsorption positions and orientations of these molecules on AGNR are determined. The adsorption energies, the charge transfer, and the density of states (DOS) are obtained. The NO, CO, and CO2 adsorbed molecules act as an acceptor, and the NH3 adsorbed molecule acts as a donor. The NO and CO molecules contributed with localized states in the center of the original band gap. But the system exhibits -type or -type semiconductor after NH3 or CO2 adsorption.

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Borodin, Dmitriy, Igor Rahinov, Pranav R. Shirhatti, Meng Huang, Alexander Kandratsenka, Daniel J. Auerbach, Tianli Zhong et al. « Following the microscopic pathway to adsorption through chemisorption and physisorption wells ». Science 369, n^o 6510 (17 septembre 2020) : 1461–65. http://dx.doi.org/10.1126/science.abc9581.

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Adsorption involves molecules colliding at the surface of a solid and losing their incidence energy by traversing a dynamical pathway to equilibrium. The interactions responsible for energy loss generally include both chemical bond formation (chemisorption) and nonbonding interactions (physisorption). In this work, we present experiments that revealed a quantitative energy landscape and the microscopic pathways underlying a molecule’s equilibration with a surface in a prototypical system: CO adsorption on Au(111). Although the minimum energy state was physisorbed, initial capture of the gas-phase molecule, dosed with an energetic molecular beam, was into a metastable chemisorption state. Subsequent thermal decay of the chemisorbed state led molecules to the physisorption minimum. We found, through detailed balance, that thermal adsorption into both binding states was important at all temperatures.

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ZAHEDI, EHSAN, ABDOLHAKIM PANGH et HAMED GHORBANPOUR. « DFT STUDY OF CO AND NO ADSORPTION ON BORON NITRIDE (BN)n = 3 - 5 NANOCLUSTERS ». Surface Review and Letters 22, n^o 01 (février 2015) : 1550005. http://dx.doi.org/10.1142/s0218625x15500055.

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Interaction of CO and NO molecules by different orientations on ( BN )n=3-5 clusters have been studied at the B3LYP/6-311+G* level of theory. Total electronic energies have been corrected for geometrical counterpoise (gCP) and dispersion (D3) energies at the B3LYP/6-31G* level. Formation of a new sigma bond between the gas and ( BN )3 cluster, atom in molecules (AIM) results, density of states spectrums (DOS), molecular electrostatic potential (MEP) surfaces, and visualization of wave function of molecular orbitals in the nearest bonding regions to the Fermi level have confirmed that adsorption of CO by carbon end atom, and NO by nitrogen end atom is covalent in nature, so that the charge transfer is occurred from gas molecule to the cluster.

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Yazaydin, A. Ozgur, Geoffrey M. Bowers et R. James Kirkpatrick. « Molecular dynamics modeling of carbon dioxide, water and natural organic matter in Na-hectorite ». Physical Chemistry Chemical Physics 17, n^o 36 (2015) : 23356–67. http://dx.doi.org/10.1039/c5cp03552j.

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Molecular dynamics modeling of systems containing a Na-exchanged hectorite and model natural organic matter molecules along with pure H₂O, pure CO₂, or a mixture of H₂O and CO₂ provides significant new insight into the molecular scale interactions among silicate surfaces, dissolved cations and organic molecules, H₂O and CO₂.

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Rho, J., M. Andersen, A. Tappe, H. Gomez, M. Smith, J. P. Bernard, T. Onaka et J. Cami. « Dust and Molecule Formation and Processing in Supernovae and their Remnants ». Proceedings of the International Astronomical Union 10, H16 (août 2012) : 583–85. http://dx.doi.org/10.1017/s1743921314012277.

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AbstractSupernovae (SNe) produce, fragment and destroy dust, molecules and nucleosynthetic elements, and reshape and modify the ISM. I will review recent infrared observations of supernova remnants (SNRs) and SNe which show that SNe are important sites of dust and molecule formation and are major dust creators in the Universe. Detection of carbon monoxide (CO) fundamental band from the young SNR Cas A indicates that astrochemical processes in SNRs interacting with molecular clouds provide astrophysical laboratories to study evolution of the ISM returning material from dense clouds into the more diffuse medium and galactic halo. Two dozen SNRs are known to be interacting with molecular clouds using H2 and millimeter observations. Recent Spitzer, Herschel and SOFIA observations along with ground-based observations have greatly advanced our understanding shock processing and astrochemistry of dust, H2, high J CO, and other neutral and ionized molecules and polycyclic aromatic hydrocarbon (PAH). Ionized molecules and warm layer of molecules that are excited by UV radiation, X-rays, or cosmic rays will be described. Finally I will discuss how astrochemical processes of dust and molecules in SNRs impact the large scale structures in the ISM.

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Chia, Tze Shyang, et Ching Kheng Quah. « Temperature-induced order–disorder structural phase transitions of two-dimensional isostructural hexamethylenetetramine co-crystals ». Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, n^o 5 (15 septembre 2017) : 879–90. http://dx.doi.org/10.1107/s2052520617009520.

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Hexamethylenetetramine-benzoic acid (1/2) (HBA) and hexamethylenetetramine-4-methylbenzoic acid (1/2) (HMBA) co-crystals undergo order–disorder structural phase transition from a low-temperature monoclinic crystal structure to a high-temperature orthorhombic crystal structure at the transition temperatures of 257.5 (5) K (Pn↔Fmm2) and 265.5 (5) K (P21/n↔Cmcm), respectively, using variable-temperature single-crystal X-ray diffraction analysis. The observed phase transitions were confirmed to be reversible first-order transitions as indicated by the sharp endothermic and exothermic peaks in the differential scanning calorimetry measurement. The three-molecule aggregate of HBA and HMBA consists of a hexamethylenetetramine molecule and two benzoic acid or two 4-methylbenzoic acid molecules, respectively. The acid molecules are ordered at the low-temperature phase and are equally disordered over two positions, which are related by a mirror symmetry, at the high-temperature phase. The two-dimensional supramolecular constructs common to both co-crystals are formed by three-molecule aggregatesviaweak intermolecular C—H...O and C—H...π interactions into molecular trilayers parallel to theacplane with smallXPacdissimilarity indices and parameters. ThePIXELinteraction energies of all corresponding molecular contacts were calculated and the results are comparable between HBA and HMBA co-crystals, resulting in similar lattice energies and transition temperatures despite their two-dimensional isostructural relationship. The observed phase transitions of these two energetically similar co-crystals are triggered by similar mechanisms,i.e.the molecular rotator ordering and structural order–disorder transformation, which induced non-merohedral twinning with similar twin matrices in the low-temperature crystal form of both co-crystals.

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Rabiller, Philippe, Bertrand Toudic, Laurent Guérin, Céline Mariette et Mark Hollingsworth. « Diffuse scattering and phase transitions in aperiodic inclusion compounds ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C621. http://dx.doi.org/10.1107/s2053273314093784.

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Small molecules, such as urea, thiourea, perhydrotriphenylene can be co-crystallised with long-chain hydrocarbon molecules to form inclusion compounds. The guest chains are confined to narrow, approximately cylindrical, channels created by the host small-molecule lattice. The stoichiometry and the conformations of the chains included inside the channels are function of internal interactions such as intra-chain interaction, but also of overall co-operative properties of the resulting three dimensionally ordered single crystal. These intergrowth compounds may form incommensurate composite crystals. A prototype example of such uniaxial intergrowth aperiodic crystals is n-alkane (CnH2n+2)/urea (CO(NH2)2). In these supra-molecular systems, urea molecules are connected by H-bonds and form helical ribbons, which repeat every six urea molecules to form a series of linear, hexagonal tunnels that can accommodate linear alkanes. Because the channels (~0.53 nm) are larger than the hydrocarbon chains, guests are held loosely and can undergo substantial motions. A significant amount of diffuse scattering of the first and second kinds can be depicted in scattering experiments, static or dynamic. These materials undergo a large variety of continuous or weakly first order structural phase transitions when changing the alkane molecule length and giving place to large pre-transitional effects. The talk will give an overview of the diffuse scattering in these compounds and will focus on connection with aperiodicity.

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Tomita, Yuji, Eri Watanabe, Masumi Shimizu, Yasuyuki Negishi, Yukihiro Kondo et Hidemi Takahashi. « Induction of tumor-specific CD8+ cytotoxic T lymphocytes from naïve human T cells by using Mycobacterium-derived mycolic acid and lipoarabinomannan-stimulated dendritic cells ». Cancer Immunology, Immunotherapy 68, n^o 10 (17 septembre 2019) : 1605–19. http://dx.doi.org/10.1007/s00262-019-02396-8.

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Abstract The main effectors in tumor control are the class I MHC molecule-restricted CD8+ cytotoxic T lymphocytes (CTLs). Tumor-specific CTL induction can be regulated by dendritic cells (DCs) expressing both tumor-derived epitopes and co-stimulatory molecules. Immunosuppressive tolerogenic DCs, having down-regulated co-stimulatory molecules, are seen within the tumor mass and can suppress tumor-specific CTL induction. The tolerogenic DCs expressing down-regulated XCR1+CD141+ appear to be induced by tumor-derived soluble factors or dexamethasone, while the immunogenic DCs usually express XCR1+CD141+ molecules with a cross-presentation function in humans. Thus, if tolerogenic DCs can be reactivated into immunogenic DCs with sufficient co-stimulatory molecules, tumor-specific CD8+ CTLs can be primed and activated in vivo. In the present study, we converted human tolerogenic CD141+ DCs with enhanced co-stimulatory molecule expression of CD40, CD80, and CD86 through stimulation with non-toxic mycobacterial lipids such as mycolic acid (MA) and lipoarabinomannan (LAM), which synergistically enhanced both co-stimulatory molecule expression and interleukin (IL)-12 secretion by XCR1+CD141+ DCs. Moreover, MA and LAM-stimulated DCs captured tumor antigens and presented tumor epitope(s) in association with class I MHCs and sufficient upregulated co-stimulatory molecules to prime naïve CD3+ T cells to become CD8+ tumor-specific CTLs. Repeat CD141+ DC stimulation with MA and LAM augmented the secretion of IL-12. These findings provide us a new method for altering the tumor environment by converting tolerogenic DCs to immunogenic DCs with MA and LAM from Mycobacterium tuberculosis.

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Lemmerer, Andreas. « Seven hexamethylenetetramine (HMTA) complexes with mono- and dicarboxylic acids : analysis of packing modes of HMTA complexes in the literature ». Acta Crystallographica Section B Structural Science 67, n^o 2 (10 mars 2011) : 177–92. http://dx.doi.org/10.1107/s0108768111004964.

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The crystal structures of seven hexamethylenetetramine (HMTA) complexes, or co-crystals, with carboxylic acid donor molecules are reported to explain the link between the molecular structure of HMTA and the crystal structure of the co-crystals, i.e. the dimension and shape of their hydrogen-bonded assembly. A comprehensive and detailed literature survey of HMTA complexes (38), be they neutral co-crystals or salts, with molecules containing carboxylic acid and phenol functional groups reveals that in general two N acceptors are used for strong O—H...N interactions. Owing to the relative arrangement of two of the four N atoms, the most common type of assembly features one-dimensional zigzag chains. Weak interactions of the C—H...N type are formed by N atoms not involved in strong interactions. These chains also form the basis of two-dimensional assemblies. These one- and two-dimensional assemblies feature either two or three functional groups. If only one functional group is on the donor molecule, then wing or V-shaped zero-dimensional assemblies are formed, which can be considered to be the building blocks for one- and two-dimensional assemblies. In general, the HMTA molecules form two-dimensional layers which are stabilized by weak hydrogen bonds. Co-crystals with cyclohexylcarboxylic acid (I), 4-fluorobenzoic acid (II), 4-methylbenzoic acid (III) and cinnamic acid (IV) all feature the V-shaped zero-dimensional assemblies. Co-crystals with cis-1,4-cyclohexyldicarboxylic acid (VI) and trans-1,4-cyclohexylcarboxylic acid (VII) feature the zigzag chains and can be structurally derived from co-crystal (I). Co-crystal (V), with 4-nitrobenzoic acid, has solvent water included and features hydrogen bonding to all four N atoms of the HMTA molecule.

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STEPHAN-OTTO ATTOLINI, CAMILLE, et PETER F. STADLER. « NEUTRAL NETWORKS OF INTERACTING RNA SECONDARY STRUCTURES ». Advances in Complex Systems 08, n^o 02n03 (juin 2005) : 275–83. http://dx.doi.org/10.1142/s0219525905000427.

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RNA molecules interact by forming inter-molecular base pairs that compete with the intra-molecular base pairs of their secondary structures. We investigate the patterns of neutral mutations in RNAs whose function is the interaction with other RNAs, i.e. the co-folding with one or more other RNA molecules. We find that (i) the degree of neutrality is much smaller in interacting RNAs compared to RNAs that just have to coform to a single externally prescribed target structure, and (ii) strengthening this contraint to the conservation of the co-folded structure with two or more partners essentially eliminates neutrality. It follows that RNAs whose function depends on the formation of a specific interaction complex with a target RNA molecule will evolve much more slowly than RNAs with a function depending only on their own structure.

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Zhou, Lingling, Yaqing Zhou, Yanli Tang, Kewu Yang, Lei Zhang, Lingxiang Gao, Guofang Zhang, Ziwei Gao et Weiqiang Zhang. « Antibacterial Fischer Carbenoid CO-Releasing Molecules ». Chinese Journal of Organic Chemistry 36, n^o 11 (2016) : 2695. http://dx.doi.org/10.6023/cjoc201603027.

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Ren, X., E. A. Gobrogge et C. A. Lundgren. « Titrating Pt Surface with CO Molecules ». Journal of Physical Chemistry Letters 10, n^o 20 (13 septembre 2019) : 6306–15. http://dx.doi.org/10.1021/acs.jpclett.9b01789.

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Jongma, Rienk T., Gert von Helden, Giel Berden et Gerard Meijer. « Confining CO molecules in stable orbits ». Chemical Physics Letters 270, n^o 3-4 (mai 1997) : 304–8. http://dx.doi.org/10.1016/s0009-2614(97)00382-5.

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30

Mann, Brian E. « CO-Releasing Molecules : A Personal View ». Organometallics 31, n^o 16 (22 juin 2012) : 5728–35. http://dx.doi.org/10.1021/om300364a.

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31

Bartels, L., G. Meyer et K. H. Rieder. « Basic steps involved in the lateral manipulation of single CO molecules and rows of CO molecules ». Chemical Physics Letters 273, n^o 5-6 (juillet 1997) : 371–75. http://dx.doi.org/10.1016/s0009-2614(97)00610-6.

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Chen, Jun, Qing Guo, Jiawei Wu, Dongxu Dai, Maodu Chen et Xueming Yang. « Acetaldehyde polymerization on Co(0001) : the role of CO ». Physical Chemistry Chemical Physics 21, n^o 16 (2019) : 8275–81. http://dx.doi.org/10.1039/c9cp00441f.

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Noland, Wayland E., Janel L. Rieger, Zoe H. Tu et Kenneth J. Tritch. « A 2:1 co-crystal of 3,5-dibromo-4-cyanobenzoic acid and anthracene ». Acta Crystallographica Section E Crystallographic Communications 73, n^o 11 (20 octobre 2017) : 1743–46. http://dx.doi.org/10.1107/s2056989017014815.

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The title co-crystal, C8H3Br2NO2·0.5C14H10, was self-assembled from a 2:1 mixture of the components in slowly evaporating dichloromethane. The molecules adopt a sheet structure parallel to (1-12) in which carboxy hydrogen-bonded dimers and anthracene molecules stagger in both dimensions. Within the sheets, six individual cyano acid molecules surround each anthracene molecule. Cyano acid molecules form one of the two possibleR22(10) rings between neighboring cyano and bromo groups. Compared to the dichloro analog [Britton (2012).J. Chem. Crystallogr.42, 851–855], the dihedral angle between the best-fit planes of acid and anthracene molecules has decreased from 7.1 to 0.9 (2)°.

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Booth, R. S., et Th De Graauw. « Molecules in the Magellanic Clouds ». Symposium - International Astronomical Union 148 (1991) : 415–20. http://dx.doi.org/10.1017/s0074180900201046.

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In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

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Tonin, Marlon D. L., Simon J. Garden, Mukesh M. Jotani, Solange M. S. V. Wardell, James L. Wardell et Edward R. T. Tiekink. « The 1:1 co-crystal of 2-bromonaphthalene-1,4-dione and 1,8-dihydroxyanthracene-9,10-dione : crystal structure and Hirshfeld surface analysis ». Acta Crystallographica Section E Crystallographic Communications 73, n^o 5 (21 avril 2017) : 738–45. http://dx.doi.org/10.1107/s2056989017005667.

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The asymmetric unit of the title co-crystal, C10H5BrO2·C14H8O4[systematic name: 2-bromo-1,4-dihydronaphthalene-1,4-dione–1,8-dihydroxy-9,10-dihydroanthracene-9,10-dione (1/1)], features one molecule of each coformer. The 2-bromonaphthoquinone molecule is almost planar [r.m.s deviation of the 13 non-H atoms = 0.060 Å, with the maximum deviations of 0.093 (1) and 0.099 (1) Å being for the Br atom and a carbonyl-O atom, respectively]. The 1,8-dihydroxyanthraquinone molecule is planar (r.m.s. deviation for the 18 non-H atoms is 0.022 Å) and features two intramolecular hydroxy-O—H...O(carbonyl) hydrogen bonds. Dimeric aggregates of 1,8-dihydroxyanthraquinone molecules assemble through weak intermolecular hydroxy-O—H...O(carbonyl) hydrogen bonds. The molecular packing comprises stacks of molecules of 2-bromonaphthoquinone and dimeric assembles of 1,8-dihydroxyanthraquinone with the shortest π–π contact within a stack of 3.5760 (9) Å occurring between the different rings of 2-bromonaphthoquinone molecules. The analysis of the Hirshfeld surface reveals the importance of the interactions just indicated but, also the contribution of additional C—H...O contacts as well as C=O...π interactions to the molecular packing.

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Xu, Chenhong, Suqin Zhou, Jing Chen, Yuxiang Wang et Lei He. « Adsorption mechanism of CO molecule on Al(111) surface : periodic DFT investigation ». Canadian Journal of Chemistry 96, n^o 12 (décembre 2018) : 993–99. http://dx.doi.org/10.1139/cjc-2018-0169.

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The adsorption mechanism of the CO molecule on Al(111) surface has been investigated systematically at the atom-molecule level by the method of periodic density functional theory. The adsorption energies, adsorption structures, charge transfer, and density of states have been calculated in a wide range of coverage. It is found that the hcp-hollow site is the energetically favorable site. A significant positive correlation has been found between the adsorption energy (Eads) and coverage. The adsorbed CO molecules are almost perpendicular on the surface with the C atom facing the surface. There is an obvious charge transfer from Al atoms to the C atom; the Al atoms that have interaction with the C atom offer the most charge. The 4σ, 1π, and 5σ molecular orbitals of CO are found to contribute to bonding with the Al. The charges filling in the 2π molecular orbital contribute to C–O bond activation. In conclusion, the passivation of aluminum surface and the activation of CO molecule occur simultaneously in the adsorption of CO on Al surface.

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Kamaal, Saima, Md Serajul Haque Faizi, Akram Ali, Musheer Ahmad et Turganbay Iskenderov. « Crystal structure of 4-[(3-methoxy-2-oxidobenzylidene)azaniumyl]benzoic acid methanol monosolvate ». Acta Crystallographica Section E Crystallographic Communications 74, n^o 12 (22 novembre 2018) : 1847–50. http://dx.doi.org/10.1107/s2056989018016262.

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In the crystal of the title compound, C15H13NO4·CH3OH, the Schiff base molecule exists in the zwitterionic form; an intramolecular N—H...O hydrogen bond stabilizes the molecular structure. The benzene rings are nearly co-planar, subtending a dihedral angle of 5.34 (2)°. In the crystal, classical O—H...O and weak C—H...O hydrogen bonds link the Schiff base molecules and methanol solvent molecules into a three-dimensional supramolecular architecture. The crystal studied was refined as an inversion twin.

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Fujimoto, Yoshitaka, et Susumu Saito. « Detection of Environmentally Toxic Molecules Using Carbon Nanotubes : A First-Principles Theoretical Study ». Journal of The Electrochemical Society 169, n^o 3 (1 mars 2022) : 037512. http://dx.doi.org/10.1149/1945-7111/ac5bab.

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The adsorption process of environmentally harmful (CO2), toxic (CO, NO and NO2) and common (O2 and N2) molecules in air on boron and nitrogen-doped carbon nanotubes (CNTs) and its effects on quantum transport are studied using the first-principles density-functional calculations combined with the quantum transport method. It is found that CO, NO, NO2 and O2 molecules can strongly bind on the B-doped (10,0) CNTs while only NO and NO2 molecules are strongly adsorbed on the N-doped (10,0) CNTs in air. Quantum transport properties of (10,0) CNTs regarding the adsorption of the molecules are quantitatively investigated, and it is found that the adsorption of the molecules changes sizably the quantum conductance of the CNTs, which depends on the types of the adsorbed molecules. The origin associated with the wide variation of the quantum conductance induced by the molecular adsorption is revealed, and the possibility to selectively detect toxic CO, NO, and NO2 molecules in air is discussed.

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39

Ogutu, Hezron, et Reinout Meijboom. « (Acetylacetonato-κ2O,O′)carbonyl[tris(naphthalen-1-yl)phosphane-κP]rhodium(I) acetone hemisolvate ». Acta Crystallographica Section E Structure Reports Online 68, n^o 4 (10 mars 2012) : m394. http://dx.doi.org/10.1107/s1600536812008148.

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The title compound, [Rh(C5H7O2)(C30H21P)(CO)]·0.5C3H6O, has two different complex molecules in the asymmetric unit, with the RhIatoms in slightly distorted square-planar coordination environments. The molecules are packed as two monomeric molecules with one acetone solvent molecule sitting at the centre.

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40

Poparic, Goran. « Resonant excitation of molecules by low-energy electrons ». Facta universitatis - series : Physics, Chemistry and Technology 6, n^o 1 (2008) : 41–55. http://dx.doi.org/10.2298/fupct0801041p.

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Low-energy electron impact vibrational and electronic excitation cross sections of the CO, N2 and CO2 molecules are measured by use of a high resolution crossed-beams double trochoidal electron spectrometer. The spectrometer is designed to work in standard and time-of-flight regimes. The energy dependences of the resonant vibrational excitation of the first several vibrational levels of the N2, CO, and CO2 molecules, have been measured. Characteristic substructures in energy excitation spectra in the cases of N2 and CO have been obtained and discussed for some vibrational channels for the first time. The ratio of forward-to-backward scattered electrons from the 2? resonance in CO is found to be equal to 1, and thus the angular distribution of scattered electrons to be symmetric relative to 90?. This conclusion supports the fact that the contribution of the p? partial wave is dominant in the energy region of the 2? resonance in CO. The energy dependences of the near threshold resonant excitation of the valence and Rydberg states of the N2 and CO molecules have been measured. The cross sections of the near threshold resonant excitation of the C 3?u valence state, and the E 3?+ g and a'' 1?+ g Rydberg states of the N2 molecule have been measured. In the case of the CO molecule, the cross sections of the near threshold resonant excitation of the a 3? valence state, and the b 3?+ and B 1?+ Rydberg states have been measured. Resonant structures in excitation functions of all measured electronic states are observed and their locations are compared with resonances obtained in different decay channels.

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41

Bhardwaj, Rajni M., Huaiyu Yang et Alastair J. Florence. « Crystal structure of the co-crystal butylparaben–isonicotinamide (1/1) ». Acta Crystallographica Section E Crystallographic Communications 72, n^o 1 (1 janvier 2016) : 53–55. http://dx.doi.org/10.1107/s2056989015023518.

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The title 1:1 co-crystal, C11H14O3·C6H6N2O [systematic name: butyl 4-hydroxybenzoate–isonicotinamide (1/1)], crystallizes with one molecule of butylparaben (BPN) and one molecule of isonicotinamide (ISN) in the asymmetric unit. In the crystal, BPN and ISN molecules form hydrogen-bonded (O—H...N and N—H...O) dimers of paired BPN and ISN molecules. These dimers are further connected to each otherviaN—H...O=C hydrogen bonds, creating ribbons in [011] which further stack along theaaxis to form a layered structure with short C...C contacts of 3.285 (3) Å. Packing interactions within the crystal structure were assessed using PIXEL calculations.

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42

Chia, Tze Shyang, et Ching Kheng Quah. « Temperature-induced phase transition of isonicotinamide-malonic acid (2/1) and supramolecular construct analysis of isonicotinamide structures ». Zeitschrift für Kristallographie - Crystalline Materials 233, n^o 8 (26 juillet 2018) : 539–54. http://dx.doi.org/10.1515/zkri-2017-2109.

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Abstract The isonicotinamide-malonic acid (2/1) co-crystal salt (2IN·C3) exhibits a first-order displacive structural phase transition from low-temperature triclinic P1̅ crystal structure to high-temperature monoclinic C2/c crystal structure and vice versa at the transition temperatures of 298 (1) and 295 (1) K, respectively, as determined by variable-temperature SCXRD analysis and DSC measurements. The asymmetric unit of 2IN·C3 comprises three malonic acid molecules and six isonicotinamide molecules at the low-temperature phase, and this is reduced to a half-molecule of malonic acid and an isonicotinamide molecule in the high-temperature phase. The carboxyl and pyridinium H atoms are disordered at both phases. The observed phase transition near room temperature is triggered by the molecular displacement of the isonicotinamide molecule and the syn-anti conformational transformation of the malonic acid molecule with deviation angles of 10.4 and 11.7°, respectively, which induced an energy change of 19.1 kJ mol−1 in the molecular cluster comprising a central isonicotinamide molecule and eight neighboring molecules. However, the total interaction energy of the molecular cluster of a central malonic acid molecule and eight neighboring molecules does not change significantly upon the phase transition. The molecules of isonicotinamide structures except IN·IN+·triazole‒ form zero-dimensional finite arrays or one-dimensional chains as the primary supramolecular construct by carboxyl···pyridyl (−35.9 to −56.7 kJ mol−1) and carboxamide···carboxamide (−53.6 to −68.7 kJ mol−1) or carboxyl···carboxamide (−52.6 to −67.1 kJ mol−1) synthons.

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Molpeceres, G., V. Zaverkin, N. Watanabe et J. Kästner. « Binding energies and sticking coefficients of H2 on crystalline and amorphous CO ice ». Astronomy & ; Astrophysics 648 (avril 2021) : A84. http://dx.doi.org/10.1051/0004-6361/202040023.

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Context. Molecular hydrogen (H2) is the most abundant interstellar molecule and plays an important role in the chemistry and physics of the interstellar medium. The interaction of H2 with interstellar ices is relevant for several processes (e.g., nuclear spin conversion and chemical reactions on the surface of the ice). To model surface processes, quantities such as binding energies and sticking coefficients are required. Aims. We provide sticking coefficients and binding energies for the H2/CO system. These data are absent in the literature so far and could help modelers and experimentalists to draw conclusions on the H2/CO interaction in cold molecular clouds. Methods. Ab initio molecular dynamics simulations, in combination with neural network potentials, were employed in our simulations. Atomistic neural networks were trained against density functional theory calculations on model systems. We sampled a wide range of H2 internal energies and three surface temperatures. Results. Our results show that the binding energy for the H2/CO system is low on average, − 157 K for amorphous CO and −266 K for crystalline CO. This carries several implications for the rest of the work. H2 binding to crystalline CO is stronger by 109 K than to amorphous CO, while amorphous CO shows a wider H2 binding energy distribution. Sticking coefficients are never unity and vary strongly with surface temperature, but less so with ice phase, with values between 0.95 and 0.17. With the values of this study, between 17 and 25% of a beam of H2 molecules at room temperature would stick to the surface, depending on the temperature of the surface and the ice phase. Residence times vary by several orders of magnitude between crystalline and amorphous CO, with the latter showing residence times on the order of seconds at 5 K. H2 may diffuse before desorption in amorphous ices, which might help to accommodate it in deeper binding sites. Conclusions. Based on our results, a significant fraction of H2 molecules will stick on CO ice under experimental conditions, even more so under the harsh conditions of prestellar cores. However, with the low H2–CO binding energies, residence times of H2 on CO ice before desorption are too short to consider a significant population of H2 molecules on pure CO ices. Diffusion is possible in a time window before desorption, which might help accommodate H2 on deeper binding sites, which would increase residence times on the surface.

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Tan, Sang Loon, et Edward R. T. Tiekink. « A 1:2 co-crystal of 2,2′-thiodibenzoic acid and triphenylphosphane oxide : crystal structure, Hirshfeld surface analysis and computational study ». Acta Crystallographica Section E Crystallographic Communications 74, n^o 12 (9 novembre 2018) : 1764–71. http://dx.doi.org/10.1107/s205698901801544x.

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The asymmetric unit of the title co-crystal, 2,2′-thiodibenzoic acid–triphenylphosphane oxide (1/2), C14H10O4S·2C18H15OP, comprises two molecules of 2,2′-thiodibenzoic acid [TDBA; systematic name: 2-[(2-carboxyphenyl)sulfanyl]benzoic acid] and four molecules of triphenylphosphane oxide [TPPO; systematic name: (diphenylphosphoryl)benzene]. The two TDBA molecules are twisted about their disulfide bonds and exhibit dihedral angles of 74.40 (5) and 72.58 (5)° between the planes through the two SC6H4 residues. The carboxylic acid groups are tilted out of the planes of the rings to which they are attached forming a range of CO2/C6 dihedral angles of 19.87 (6)–60.43 (8)°. Minor conformational changes are exhibited in the TPPO molecules with the range of dihedral angles between phenyl rings being −2.1 (1) to −62.8 (1)°. In the molecular packing, each TDBA acid molecule bridges two TPPO molecules via hydroxy-O—H...O(oxide) hydrogen bonds to form two three-molecule aggregates. These are connected into a three-dimensional architecture by TPPO-C—H...O(oxide, carbonyl) and TDBA-C—H...(oxide, carbonyl) interactions. The importance of H...H, O...H/H...O and C...H/H...C contacts to the calculated Hirshfeld surfaces has been demonstrated. In terms of individual molecules, O...H/H...O contacts are more important for the TDBA (ca 28%) than for the TPPO molecules (ca 13%), as expected from the chemical composition of these species. Computational chemistry indicates the four independent hydroxy-O—H...O(oxide) hydrogen bonds in the crystal impart about the same energy (ca 52 kJ mol−1), with DTBA-phenyl-C—H...O(oxide) interactions being next most stabilizing (ca 40 kJ mol−1).

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Knudsen, Kirsten Kraiberg. « Observations of Molecules in High Redshift Galaxies ». Proceedings of the International Astronomical Union 7, S280 (juin 2011) : 325–38. http://dx.doi.org/10.1017/s1743921311025087.

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AbstractI present an overview of the molecular gas observations in high redshift galaxies. This field has seen tremendous progress in the past few years, with an increased number of detections of other molecules than CO. The molecular line observations are done towards different classes of massive starbursts, including submillimeter galaxies, quasars, and massive gas-rich disks. I will highlight results of detections of HCN, HCO+, and other small molecules, as well as the Spitzer detections of PAHs. Additionally, I will discuss about the excitation of CO and other species in the high-z galaxies and put this in the context of new telescopes such as ALMA.

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Siegmann, B., U. Werner et H. O. Lutz. « Multiple Ionisation and Fragmentation of Molecules ». Australian Journal of Physics 52, n^o 3 (1999) : 545. http://dx.doi.org/10.1071/ph98089.

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The multiple ionisation and dissociation of molecules, e.g. H2, N2, H2O, CH4 and C60, by fast ions was studied using a position- and time-sensitive multi-particle detector. The data obtained allow a clear separation of various reaction channels. Of special interest are the ‘Coulomb explosion’ processes like N2 → Nq+ +Nn+ or H2O → H+ + H+ +On+. For these reactions the coincident measurement of the momenta of correlated fragment ion yields a kinematically complete image of the molecular break-up process, and the fragmentation energy as well as angular correlations can be derived for each individual event. In the case of H2 as target molecule the CE model describes the fragmentation energy rather well, whereas in the case of more complex molecules, e.g. N2, CO and CH4, the simple CE model is insufficient to explain the measured energy and angular spectra. Better agreement was achieved with ab initio MCSCF calculations which take into account several molecular states of the fragmenting highly charged molecular ion.

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Shi, Hui Fang, Tao Wu, Peng Gang Jiang, Zhi Hao et Miao Miao Zhang. « Hexaaquacobalt(II) 2,2′-[naphthalene-1,8-diylbis(oxy)]diacetate dihydrate ». Acta Crystallographica Section E Structure Reports Online 69, n^o 2 (12 janvier 2013) : m103—m104. http://dx.doi.org/10.1107/s1600536813000512.

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In the title compound, [Co(H2O)6](C14H10O6)·2H2O, the 2,2′-[naphthalene-1,8-diylbis(oxy)]diacetate dianionLis not coordinated to the CoIIion. The asymmetric unit contains half of theLdianion, half of a [Co(H2O)6]2+cation (both molecules being completed by inversion symmetry), and one water molecule. The crystal packing features O—H...O hydrogen bonding between the carboxylate groups, the aqua ligands and the hydrate water molecules.

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Lini, Freshsya Zata, Dhanang Edy Pratama et Tu Lee. « Co-Crystallization Kinetics of 2:1 Benzoic Acid–Sodium Benzoate Co-Crystal : The Effect of Templating Molecules in a Solution ». Crystals 11, n^o 7 (12 juillet 2021) : 812. http://dx.doi.org/10.3390/cryst11070812.

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The addition of dissolved templating molecules in crystallization will create “supramolecular assemblies” within the solution, serving as “anchor points” for the solute molecules to nucleate and grow. In this work, nucleation and crystal growth kinetics of 2:1 benzoic acid (HBz)–sodium benzoate (NaBz) co-crystallization with or without templates in a solution were analyzed by monitoring the concentration of the mother liquor during cooling crystallization. The results showed that the addition of the dissolved 2:1 or 1:1 HBz–NaBz co-crystals as templating molecules could reduce the critical free energy barrier of 2:1 HBz–NaBz co-crystal during its nucleation, but did not significantly affect the order of crystal growth rate. On the other hand, the critical free energy barrier of the nucleation process was increased if dissolved NaBz was used as a templating molecule, while a significant rise in the order of crystal growth rate occurred. The crystal habit obtained from the NaBz-templated system was needle-like, suggesting that sodium–sodium coordination chains of NaBz supramolecular assemblies in the solution phase were responsible for creating elongated crystals. Conversely, a large prismatic crystal habit found in non-templated and 2:1 and 1:1 HBz–NaBz co-crystal-templated systems implied that those templating molecules formed sparsely interconnected supramolecular assemblies in the solution phase.

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Sato, Younosuke, Isamu Okamoto, Hiroki Kameyama, Shinji Kudoh, Haruki Saito, Mune Sanada, Noritaka Kudo et al. « Integrated Immunohistochemical Study on Small-Cell Carcinoma of the Lung Focusing on Transcription and Co-Transcription Factors ». Diagnostics 10, n^o 11 (13 novembre 2020) : 949. http://dx.doi.org/10.3390/diagnostics10110949.

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Small-cell lung cancer (SCLC) is an aggressive malignant cancer that is classified into four subtypes based on the expression of the following key transcription and co-transcription factors: ASCL1, NEUROD1, YAP1, and POU2F3. The protein expression levels of these key molecules may be important for the formation of SCLC characteristics in a molecular subtype-specific manner. We expect that immunohistochemistry (IHC) of these molecules may facilitate the diagnosis of the specific SCLC molecular subtype and aid in the appropriate selection of individualized treatments. We attempted IHC of the four key factors and 26 candidate SCLC target molecules selected from the gene expression omnibus datasets of 47 SCLC samples, which were grouped based on positive or negative results for the four key molecules. We examined differences in the expression levels of the candidate targets and key molecules. ASCL1 showed the highest positive rate in SCLC samples, and significant differences were observed in the expression levels of some target molecules between the ASCL1-positive and ASCL1-negative groups. Furthermore, the four key molecules were coordinately and simultaneously expressed in SCLC cells. An IHC study of ASCL1-positive samples showed many candidate SCLC target molecules, and IHC could become an essential method for determining SCLC molecular subtypes.

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Batten, P., T. Heaton, S. Fuller-Espie et R. I. Lechler. « Human anti-mouse xenorecognition. Provision of noncognate interactions reveals plasticity of T cell repertoire. » Journal of Immunology 155, n^o 3 (1 août 1995) : 1057–65. http://dx.doi.org/10.4049/jimmunol.155.3.1057.

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Abstract DAP.3 transfectants expressing native H-2E molecules with or without human LFA-3 and ICAM-1 (intercellular adhesion molecule-1) failed to induce proliferation by human peripheral blood T cells. Introduction of sequence from the DR beta 2 domain into the H-2E molecule led to the induction of detectable proliferation, which was substantially augmented by co-expression of human LFA-3 and ICAM-1 to levels comparable to those induced by DAP.3 cells co-expressing wild-type DR alloantigens with human LFA-3/ICAM-1. In marked contrast, cells expressing native H-2A molecules together with human accessory molecules provoked strong primary proliferative responses. The results of Ab inhibition experiments confirmed that this was caused by direct xenorecognition. In limiting dilution assays the frequency of anti-H-2A, IL-2-secreting, CD4+ human T cells was only fivefold lower than that measured against a DR alloantigen expressed on the same background. No measurable frequency was recorded against H-2E-expressing cells. Evidence to suggest that this difference was a result of isotype-specific differences in the interaction with CD4 was provided using transfectants expressing DR alloantigens with either the H-2E or H-2A beta 2 domain. DR molecules with the H-2A beta 2 domain stimulated a substantially stronger response than those with the H-2E beta 2 domain. These results challenge the view that xenogeneic T cell responses between evolutionarily distant species are weak; further emphasize the influence of the interaction between the T cell co-receptor molecule CD4, with its MHC class II molecular ligand on the strength of primary xenoresponses; and suggest that MHC class II isotypes may differ substantially in their interaction with CD4.

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