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21.
A molecular dynamics simulation combined with semiempirical quantum mechanics calculations has been performed to investigate the structure, dynamical, and electronic properties of pure C60 in liquid ethanol. The behavior of the fullerene alcoholic solution was obtained by using the NPT ensemble under ambient conditions, including one C60 fullerene immersed in 1000 ethanol molecules. Our analyzed center-of-mass pairwise radial distribution function indicated that, on average, there are 32, 72, 132, and 187 ethanol molecules around, respectively, the first, second, third, and fourth solvation shells of the C60 molecule. To investigate the UV-vis transition energies of C60 in the presence of ethanol, we have considered constituents of the time uncorrelated supramolecular structures of the first solvation shell, i.e., clusters of C60@{EtOH}32 types. The semiempirical calculations were performed at the intermediate neglect of differential overlap level with configuration interaction singles (INDO/CIS). Our results have pointed out that the characteristic C60 UV-vis absorbance peaks are slightly shifted to longer wavelengths, as compared to the isolated molecule. These findings are in connection with the weak donor-acceptor character of the interactions involving electron lone pairs of oxygen atoms on the solvent and the fullerene surface. 相似文献
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Rosie J. Somerville Andryj M. Borys Marina Perez-Jimenez Ainara Nova David Balcells Lorraine A. Malaspina Simon Grabowsky Ernesto Carmona Eva Hevia Jesús Campos 《Chemical science》2022,13(18):5268
More than four decades ago, a complex identified as the planar homoleptic lithium nickelate “Li3NiPh3(solv)3” was reported by Taube and co-workers. This and subsequent reports involving this complex have lain dormant since; however, the absence of an X-ray diffraction structure leaves questions as to the nature of the Ni–PhLi bonding and the coordination geometry at Ni. By systematically evaluating the reactivity of Ni(COD)2 with PhLi under different conditions, we have found that this classical molecule is instead a unique octanuclear complex, [{Li3(solv)2Ph3Ni}2(μ-η2:η2-C6H4)] (5). This is supported by X-ray crystallography and solution-state NMR studies. A theoretical bonding analysis from NBO, QTAIM, and ELI perspectives reveals extreme back-bonding to the bridging C6H4 ligand resulting in dimetallabicyclobutane character, the lack of a Ni–Ni bond, and pronounced σ-bonding between the phenyl carbanions and nickel, including a weak σC–Li → sNi interaction with the C–Li bond acting as a σ-donor. Employing PhNa led to the isolation of [Na2(solv)3Ph2NiCOD]2 (7) and [Na2(solv)3Ph2(NaC8H11)Ni(COD)]2 (8), which lack the benzyne-derived ligand. These findings provide new insights into the synthesis, structure, bonding and reactivity of heterobimetallic nickelates, whose prevalence in organonickel chemistry and catalysis is likely greater than previously believed.We disclose the actual octanuclear nature of the major compound from reacting Ni(COD)2 and PhLi, assigned for more than four decades as ‘Li3NiPh3(solv)3’. We provide a thorough bonding analysis and discuss its potential implications in catalysis. 相似文献
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D. C. Malaspina E. P. Schulz L. M. Alarcón M. A. Frechero G. A. Appignanesi 《The European physical journal. E, Soft matter》2010,32(1):35-42
By means of molecular dynamics simulations we study the structure and dynamics of water molecules in contact with a model
hydrophobic surface: a planar graphene-like layer. The analysis of the distributions of a local structural index indicates
that the water molecules proximal to the graphene layer are considerably more structured than the rest and, thus, than the
bulk. This structuring effect is lost in a few angstroms and is basically independent of temperature for a range studied comprising
parts of both the normal liquid and supercooled states (240K to 320K). In turn, such structured water molecules present a
dynamics that is slower than the bulk, as a consequence of their improved interactions with their first neighbors. 相似文献
24.
Gianfranco Casnati Daniele Faenzi Francesco Malaspina 《Journal of Pure and Applied Algebra》2018,222(3):585-609
In the present paper we completely classify locally free sheaves of rank 2 with vanishing intermediate cohomology modules on the image of the Segre embedding and its general hyperplane sections.Such a classification extends similar already known results regarding del Pezzo varieties with Picard numbers 1 and 3 and dimension at least 3. 相似文献
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Marian Olaru Daniel Duvinage Yannik Naß Lorraine A. Malaspina Stefan Mebs Jens Beckmann 《Angewandte Chemie (International ed. in English)》2020,59(34):14414-14417
Transient phosphenium and arsenium ions, generated by fluoride abstraction from bis(m‐terphenyl)fluoropnictogens, underwent intramolecular electrophilic attack prior to methyl group migration and gave rise to isolable 9‐phospha‐ and 9‐arsena‐fluorenium ions. 相似文献
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Lorraine A. Malaspina Allan H. White Dieter Wege Michael B. Tolmie Brian W. Skelton Simon Grabowsky 《Structural chemistry》2017,28(5):1343-1357
Acyl-pyrazolones exist in four different tautomeric forms (two keto and two enol) in crystal structures. Routine crystal structure refinements using an independent atom model and routine isolated-molecule calculations fail in locating the mobile hydrogen atoms accurately in 22 investigated acyl-pyrazolone examples. However, a combination of both within the framework of quantum crystallography represented by the method of Hirshfeld atom refinement accurately locates the mobile hydrogen atom in a resonance-assisted hydrogen bond of title compound 3, a novel photolysis product. The impact of the hydrogen atom position on the resonance system of the non-hydrogen framework of the various tautomers is discussed, and the importance of intermolecular interactions for the positioning of the hydrogen atom is highlighted. 相似文献
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Francesco Malaspina 《Ricerche di matematica》2008,57(1):55-64
We prove a few splitting criteria for vector bundles on a quadric hypersurface and Grassmannians. We give also some cohomological
splitting conditions for rank 2 bundles on multiprojective spaces. The tools are monads and a Beilinson’s type spectral sequence
generalized by Costa and Miró-Roig.
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