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151.
Alexander Punter Paola Nava Yannick Carissan 《International journal of quantum chemistry》2020,120(11):e26180
Following on from a previous work (Punter et al., IJQC 2019, 119, 23), pseudopotential sets are developed and tested for a variety of sp2 and sp3 carbon fragments. These fragments contain only one or two explicit protons and electrons, and make use of non-atom-centered potentials. They are tested with density functional theory calculations in a selection of chemical environments in which several physical characteristics, including orbital and first ionization energies, are found to be well reproduced. They are then employed in the reproduction of molecular absorption spectra for large organic molecules and carbon allotropes, and are found to recreate both absorption and electronic circular dichroism spectra to a high accuracy. They are also found significantly to increase the computational efficiency of time dependent density functional theory (TDDFT) calculations in which they are used. 相似文献
152.
153.
Long J Chelebaeva E Larionova J Guari Y Ferreira RA Carlos LD Almeida Paz FA Trifonov A Guérin C 《Inorganic chemistry》2011,50(20):9924-9926
New cyano-bridged coordination polymers [Nd(phen)(2)(DMF)(2)(H(2)O)Mo(CN)(8)]·2H(2)O (1) and [Nd(phen)(DMF)(5)M(CN)(8)]·xH(2)O [M = Mo (2), W (3); phen = 1,10-phenanthroline] have one-dimensional structures with variable number of phenanthroline ligands. Compounds exhibit photoluminescence in the near-infrared region and ferromagnetic Nd(3+)-M(5+) interactions. 相似文献
154.
Yannick VianoDominique Bonhomme Annick Ortalo-MagnéOlivier P. Thomas Mohamed El HattabLouis Piovetti Yves BlacheGérald Culioli 《Tetrahedron letters》2011,52(9):1031-1035
A phytochemical investigation of a Mediterranean brown alga (Dictyota sp.) led to the isolation of a novel C40bis-diterpene, named dictyotadimer A. The chemical structure of this unusual dissymmetric dimer, characterized by a C-C linkage between two different xenicane units, was elucidated by 1D and 2D NMR analyses together with HR-ESI mass spectrometry. The relative configuration of the two diterpenoid components was determined by NOESY NMR correlations and molecular modeling. A plausible biogenetic pathway of dictyotadimer A was also proposed. 相似文献
155.
156.
Lartigue L Pflieger R Nikitenko SI Guari Y Stievano L Sougrati MT Larionova J 《Physical chemistry chemical physics : PCCP》2011,13(6):2111-2113
The autocatalytic sonochemical reaction of Fe(CO)(5) decomposition in [BuMeIm][Tf(2)N] provides iron nanoparticles in higher yields than in tetralin. Such a difference is explained by the higher decomposition of the intermediate Fe(3)(CO)(12) according to the two-sites model of the sonochemical reactions and the specific properties of the ionic liquid. 相似文献
157.
Toumieux S Beniazza R Desvergnes V Aráoz R Molgó J Landais Y 《Organic & biomolecular chemistry》2011,9(10):3726-3732
A straightforward access to the C10-C20 skeleton of gymnodimine, incorporating a tetrahydrofuran fragment, is described. The elaboration of the THF moiety is based on a stereocontrolled Ueno-Stork cyclization. A Lewis-acid mediated allylation of the resulting acetal at C13 and a Horner-Wadsworth-Emmons olefination on the ketone at C17 complete the synthesis. 相似文献
158.
Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ~60 μm for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ~2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice nucleation rate coefficients into agreement. The experimentally derived ice nucleation data are applied to constrain the water activity-based homogeneous ice nucleation theory to smaller than ±1 order of magnitude compared to the predictive uncertainty of larger than ±6 orders of magnitude. The atmospheric implications of these findings are discussed. 相似文献
159.
Tauran Y Grosso M Brioude A Kassab R Coleman AW 《Chemical communications (Cambridge, England)》2011,47(36):10013-10015
The complexation of nucleosides and nucleotides by hybrid nanoparticles capped by para-sulfonato-calix[4]arene shows clear discrimination between purine and pyrimidine based molecules. For the pyrimidine nucleotides there is appearance of a new absorption band around 550 nm, and a colour change from yellow to orange red and pink. 相似文献
160.
Megouda N Cofininier Y Szunerits S Hadjersi T Elkechai O Boukherroub R 《Chemical communications (Cambridge, England)》2011,47(3):991-993
The communication reports on the high performance of hydrogen-terminated silicon nanowires and silicon nanowires coated with metal (Ag, Cu) nanostructures for the photodegradation of rhodamine B under UV and visible light irradiation. 相似文献