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1.
Malysheva L Onipko A Valiokas R Liedberg B 《The journal of physical chemistry. B》2005,109(27):13221-13227
First-principle modeling is used to obtain a comprehensive understanding of infrared reflection absorption (RA) spectra of helical oligo(ethylene glycol) (OEG) containing self-assembled monolayers (SAMs). Highly ordered SAMs of methyl-terminated 1-thiaoligo(ethylene glycols) [HS(CH2CH2O)(n)CH3, n = 5, 6] on gold recently became accessible for systematic infrared analyses [Vanderah et al., Langmuir, 2003, 19, 3752]. We utilized the quoted experimental data to validate the first-principle modeling of infrared RA spectra of HS(CH2CH2O)(5,6)CH3 obtained by (i) DFT methods with gradient corrections (using different basis sets, including 6-311++G) and (ii) HF method followed by a M?ller-Plesset (MP2) correlation energy correction. In focus are fundamental modes in the fingerprint and CH-stretching regions. The frequencies and relative intensities in the calculated spectra for a single molecule are unambiguously identified with the bands observed in the experimental RA spectra of the corresponding SAMs. In addition to confirming our earlier assignment of the dominating peak in the CH-stretching region to CH2 asymmetric stretching vibrations, all other spectral features observed in that region have received an interpretation consistent (but not in all cases coinciding) with previous investigations. The obtained results provide an improved understanding of the orientation and conformation of the molecular building blocks within OEG-containing assemblies, which, in our opinion, is crucial for being able to predict the folding and phase characteristics and interaction of OEG-SAMs with water and proteins. 相似文献
2.
L. V. Shmygleva A. V. Pisareva R. V. Pisarev A. E. Ukshe Yu. A. Dobrovol’skii 《Russian Journal of Electrochemistry》2013,49(8):801-806
The proton conductivity of hydrates of calix[4]arene-para-sulfonic acids is studied. The high proton conductivity is observed at ambient temperatures in the wide ranges of environmental humidity and, correspondingly, water content in the hydrate. For the air humidity of 10 rel. %, the conductivity of compounds is 10?4-10?3 S cm?1 and approaches 10?2-10?1 S cm?1 as the humidity increases up to 70 rel. %. 相似文献
3.
We report the exact solution of the spectral problem for a graphene sheet framed by two armchair- and two zigzag-shaped boundaries. The solution is found for the pi electron Hamiltonian and gives, in particular, a closed analytic expression of edge-state energies in graphene. It is shown that the lower symmetry of graphene, in comparison with C6h of 2D graphite, has a profound effect on the graphene band structure. This and other results obtained have far-reaching implications for the understanding of graphene electronics. Some of them are briefly discussed. 相似文献
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L. V. Shmygleva R. R. Kayumov A. I. Karelin Yu. A. Dobrovol’skii 《Russian Journal of Electrochemistry》2018,54(5):409-414
Calix[4]arenesulfonic acid complexation with perchloric acid is studied. The stoichiometric composition of the complex is shown to be calix[4]arene/HClO4 = 1/1. The complex is most stable against humidity changes as far as its proton-conducting properties are concerned. Its specific proton conductivity varies from 3 × 10–3 to 5 × 10–2 S/cm; the conductivity activation energy is 0.16 ± 0.04 eV. The studying of the effect of HClO4 amount on the samples’ physico-chemical properties at low humidity showed the proton transfer in the material to be determined by the crystallites’ bulk, rather than surface, characteristics. 相似文献
6.
Under the constraint that sulfur atoms form a hexagonal (square root 3 x square root 3)R30 degrees overlayer on the (111) gold surface, the optimized geometry of periodic arrays of HS(CH2)3CONH-(CH2CH2O)3H molecules has been found ab initio, by exploiting the BP86 exchange-correlation functional with 6-31G and "general" basis sets. The obtained data suggests that several prominent features of in-SAM molecular geometry and orientation stand out from conclusions based on single-molecule modeling. In particular, changing of amide-related dihedrals is shown to dominate in adjustment of molecular constituents to the assembly environment and to result in a substantial shortening of the hydrogen bond distance between nearest-neighbor amides. First demonstrated here, the full account to the intermolecular interaction within periodic arrays of amide-bridged, oligo(ethylene glycol)-terminated alkanethiolates forms a new platform for arguable modeling of SAM apparent properties. 相似文献
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Zyubin A. S. Zyubina T. S. Sanginov E. A. Kayumov R. R. Shmygleva L. V. Dobrovol’skii Yu. A. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(5):901-907
Russian Journal of Physical Chemistry A - Quantum chemical modeling is performed for the distancing of lithium and ammonium cations from the –O–CF2–CF2–SO$$_{3}^{ - }$$... 相似文献
8.
A. V. Pisareva R. V. Pisarev A. I. Karelin L. V. Shmygleva I. S. Antipin A. I. Konovalov S. E. Solovieva Yu. A. Dobrovolsky S. M. Aldoshin 《Russian Chemical Bulletin》2012,61(10):1892-1899
High proton conductivity in calix[n]arene-para-sulfonic acid hydrates (n = 4, 8) reaching a value of 10?1 Ohm?1 cm?1 at a relative humidity of 80% was revealed for the first time. This value is close to the record conductivity of solid proton conductors and acid water solutions. The dependence of proton transfer parameters and water quantity in the title compounds dependent on the relative humidity of air was investigated. 相似文献
9.
Rimma V. Golovnya Lyuba A. Syomina Alexei L. Samusenko 《Journal of separation science》1997,20(11):611-614
It has been demonstated that the considaerable difference in temperature increments of sorption parameters of n-alkanes under isothermal conditions is the main reason for nonlinear dependence of sorption parameters on molecular mass of homolog in temperaturre programmed gas chromatography (TPGC). A new nonlinear 4th parameter equation has been given for calculation of the retention indices. Coefficients of the equation are calculated from n-alkanes. The equation allows extrapolation and interpolation calculations of retention indices under TPGC conditions with experimental precision. The results obtained; for fatty acidkl methyl esters demonstrate the advantage of ovr equation in comparison with van den Dool and Kratz's equation. 相似文献
10.
A. E. Ukshe L. V. Shmygleva A. V. Pisareva N. G. Bukun Yu. A. Dobrovol’skii 《Russian Journal of Electrochemistry》2013,49(8):807-812
Proton conductivity of special class of aromatic sulfonic acids is described, in particular, calixarene sulfonic acids that consist of flat anionic layers interlinked by labile two-dimensional hydrogen-bond network. High proton conductivity of their hydrates was observed earlier. The dependence of their transport characteristics (the proton conductivity, the activation energy of conductivity) was shown to have threshold character. The studied systems’ behavior is described on basis of percolation model that assumes changing of the proton transport mechanism at low water content in the structure. 相似文献