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1.
A method is proposed for fragment calculation of electronic structures of polyatomic molecules in the ground state. The wave
function of a molecule in the ground state in single-determinantal representation of a closed shell is employed. The concise
formulation allows efficient calculation of the electronic structures of polyatomic molecules taking into account possible
charge transfer between interacting molecular fragments.
V.I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 36, No. 3, pp. 387–394, May–June, 1995.
Translated by I. Izvekova 相似文献
2.
The structures of the perylene molecule in the first excited 11 0B2u state and the band shape (vibrational structure) of its fluorescence and absorption spectra are computed by the parametric
method. A fragmentary approach and the molecular fragments H/1C= with the parameters obtained for acenes and polyenes are
used to form molecular models in the excited state. It is shown that a model that corresponds to the choice of fragments with
the parameters of acenes is the most optimal. The theoretical spectra satisfactorily reproduce both qualitatively and quantitatively,
the basic specific features of the vibrational structure of the experimental spectra. Calculation results show high degree
of transfer of the parameters of the method in a series of related molecules not only for acenes with “linear” arrangement
of the rings (benzene, naphthalene, anthracene, etc.) but also for more complex structures (perylene). It is shown that the
parametric method developed is efficient for predicting the vibronic spectra and the structure of the excited states of complex
molecules.
Translated fromZhurnal Struktumoi Khimii, Vol.40, No. 2, pp. 242–250, March–April, 1999. 相似文献
3.
I. I. Volchenskova L. V. Keisevich S. A. Shalimov N. N. Maidanevich M. V. Nezhina 《Journal of Structural Chemistry》1997,38(3):415-421
A new compound of cis-chlorodiammineplatinum(II) with normal and deprotonated guanine has been synthesized and studied by
FAB MS. The compound has a molecular structure of a binuclear complex. The mass spectrometric behavior of the complex is dictated
by the variable valence of platinum and chemical ionization of fragments by protons, as well as by the fact that the guanine
molecule bridges the two cis-PtCl(NH3)2 groups by its N7 and OC6 atoms and the two gpanine anions bridge the groups by their N1 and OC6 atoms. The differences in
the mutual arrangement of the anions and the guanine molecule are responsible for the formation of the head-to-head and head-to-tail
structural isomers.
Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 3, pp. 503–510, May–June, 1997. 相似文献
4.
Jacques Gabarro-Arpa 《Journal of mathematical chemistry》2007,42(4):691-706
In the first work of this series (Gabarro-Arpa, Comp. Biol. Chem. 27 (2003) 153–159) it was shown that the conformational
space of a molecule could be described to a fair degree of accuracy by means of a central hyperplane arrangement. The hyperplanes
divide the space into a hierarchical set of cells that can be encoded by the face lattice poset of the arrangement. The model
however, lacked explicit rotational symmetry, which made impossible to distinguish rotated structures in conformational space.
This problem was solved in a second work (Gabarro-Arpa, Proc. 26th Ann. Int. Conf. of the IEEE EMBS (San Franciso, 2004) 3007–3010) by sorting the elementary 3-dimensional components of the molecular system into a set of
morphological classes that can be properly oriented in a standard 3-D reference frame. This also made possible to find a solution
to the problem that is being addressed in the present work: for a molecular system immersed in a heat bath we want to enumerate the subset of cells in conformational space that are visited
by the molecule in its thermal wandering. If each visited cell is a vertex on a graph with edges to the adjacent cells, here it is explained how such graph can be
built. 相似文献
5.
The parameters of the adiabatic model of the stilbene molecule in the excited state and the vibrational structure of the fluorescence
spectrum are calculated by the parametric method of the theory of vibronic spectra of complex molecules. The first and second
orders of theory are used. The molecular models are constructed by the fragment method. Satisfactory agreement with experiment
is obtained. The parameters of molecular fragments are shown to be highly transferable. The model and the spectrum max be
refined in the second order of theory using only one additional parameter for CCC angles (optimal values were obtained). The
parametric method under discussion makes it possible to predict variations of structural parameters due to excitation and
to calculate the vibrational structure of the electronic spectra of complex molecules, including characteristic variations
of the spectra in series of related molecules (stilbene-di-phenylpolyenes). This method surpasses all previous procedures
(in particular, the correlation method) in completeness and accuracy of results.
Translated fromZhurnal Strukturnoi Khinii, Vol. 41, No. 2, pp. 369–378, March–April, 2000. 相似文献
6.
A fragment method is proposed to calculate the electronic structures of polyatomic molecules in the ground state. Localization
and delocalization of the electronic states of molecular fragments are calculated simultaneously. The compact formulation
of the method allows algorithmically efficient calculations of the electronic structures of interacting molecular fragments
as well as of the whole molecules.
V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 36, No. 3, pp. 395–400, May–June, 1995.
Translated by I. Izvekova 相似文献
7.
Two molecular double-supporting polyoxotungstates [SiW12O40{M(phen)2H2O}2] · nH2O (phen = 1,10′-phenanthroline, M = Mn 1, n = 2; M = Co 2, n = 3) were synthesized hydrothermally and characterized by elemental analyses, IR, TG, and X-ray single-crystal diffraction.
The variable-temperature magnetic susceptibilities were measured at 2–300 K. The double-supporting polyoxotungstate molecule
consists of a Keggin-type dodecatungstosilicate anion and a pair of transition metal complex fragments which are covalently
linked to opposite sides of the Keggin anion. The transition metal ion locates in the center of a distorted octahedron. Multiple
H-bonding interactions are observed between the coordinated waters of the transition metal complex fragments and terminal
oxygen atoms of Keggin units and also between the bridging oxygen atoms of Keggin units and the lattice waters, which creates
one-dimensional chains or two-dimensional layers. Between the layers or chains there are weak CH···O hydrogen bonding interactions
and van der Waals forces. The molecular double-supporting polyoxotungstosilicate begins to decompose at ca. 500 °C. The variable-temperature
magnetic behavior of 1 shows weak antiferromagnetic characteristics with a small value of θ = −0.289 K. 相似文献
8.
Knehans T Schüller A Doan DN Nacro K Hill J Güntert P Madhusudhan MS Weil T Vasudevan SG 《Journal of computer-aided molecular design》2011,25(3):263-274
An in silico fragment-based drug design approach was devised and applied towards the identification of small molecule inhibitors of the
dengue virus (DENV) NS2B-NS3 protease. Currently, no DENV protease co-crystal structure with bound inhibitor and fully formed
substrate binding site is available. Therefore a homology model of DENV NS2B-NS3 protease was generated employing a multiple
template spatial restraints method and used for structure-based design. A library of molecular fragments was derived from
the ZINC screening database with help of the retrosynthetic combinatorial analysis procedure (RECAP). 150,000 molecular fragments
were docked to the DENV protease homology model and the docking poses were rescored using a target-specific scoring function.
High scoring fragments were assembled to small molecule candidates by an implicit linking cascade. The cascade included substructure
searching and structural filters focusing on interactions with the S1 and S2 pockets of the protease. The chemical space adjacent
to the promising candidates was further explored by neighborhood searching. A total of 23 compounds were tested experimentally
and two compounds were discovered to inhibit dengue protease (IC50 = 7.7 μM and 37.9 μM, respectively) and the related West Nile virus protease (IC50 = 6.3 μM and 39.0 μM, respectively). This study demonstrates the successful application of a structure-guided fragment-based
in silico drug design approach for dengue protease inhibitors providing straightforward hit generation using a combination of homology
modeling, fragment docking, chemical similarity and structural filters. 相似文献
9.
E. P. Styngach S. T. Malinovskii L. P. Bets L. A. Vlad M. Gdanets F. Z. Makaev 《Journal of Structural Chemistry》2005,46(4):765-769
Crystal and molecular structure of a new homodrimanic compound (1S,2S,4aS, 8aS)-N-(N-allyldiaminomethanethione)-1-(2-hydroxy-2,5,5,8a-tetramethyldecahydronaphthalenyl) acetamide has been determined by X-ray
diffraction analysis. The crystal is monoclinic, unit cell parameters are: a = 9.577(2) Å, b = 7.414(1) Å, c = 16.856(3) Å; β = 94.83(3)°, space group P21, Z = 2, of composition C20H35N3O2S. Two cyclohexan fragments have ordinary structure and chair-configuration typical of this compound class in homodrimanic
skeleton. Ethanol molecule is located in the outer sphere. The withdrawal of carbon atoms from planar fragments of cyclohexan
rings varies within the limits from 0.722(5) Å to − 0.634(5) Å. A dihedral angle between the mean-square planes of the latter
equals 16.0(2)°, torsion angle (5)-(5)-(10)-(16) 171.0(1)° indicates their trans-joint. In the side non linear chain allyl group is connected to terminal nitrogen atom of thiosemicarbazide molecule. Intermolecular
hydrogen bonds between carbonyl atom of acetamide fragment, ethanol molecule, and donor-acceptor groups of thiosemicarbazide
moiety play the main part in crystal structure organization.
Original Russian Text Copyright ? 2005 by E. P. Styngach, S. T. Malinovskii, L. P. Bets, L. A. Vlad, M. Gdanets, and F. Z.
Makaev
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 4, pp.785–789, July–August, 2005. 相似文献
10.
11.
A qualitative algorithm for construction of large clusters of silica gel model structures is used. According to this algorithm
and in line with our classification of dispersive silicas, silica gel is regarded as cyclosilica, which is characterized by
loose packing of the cycles of silicon-oxygen tetrahedra. A model of silica gel structure is proposed, where the primary structural
fragments are hollow frameworks with a network surface. The units of the surface network are formed by nonplanar [SiO4] chain cycles of various sizes. This structural model makes it possible to explain the peculiarities of the vibration spectra
of the framework, hydroxyl, and aqueous components of silica gels.
Institute of Surface Chemistry, Ukrainian Academy of Sciences. Russian University of Peoples' Friendship. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 3, pp. 27–34, May–June, 1994.
Translated by O. Kharlamova 相似文献
12.
Structural data representation and search for structural analogs in molecular spectroscopy databases
A method for encoding structural formulas of organic compounds using two varieties of the tree code is suggested. The tree
code is a sequence of symbols, each corresponding to an edge of a molecular graph traced around in width or in depth. The
deep tree code provides compact storage of structural formulas and rapid substructure search. The wide tree code is a basis
for a structure collection classifier providing quick access to structurally related compounds. Three techniques for selecting
structural analogs of the compound using the classifier are proposed. Databases on mass and13C NMR spectra serve as illustrations.
Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 6, pp. 1129–1139, November–December, 1996.
Translated by L. Smolina 相似文献
13.
Paul David William Bottomley Stéphane Brémier Dimitri Papaioannou Clive Thomas Walker 《Mikrochimica acta》2002,139(1-4):27-38
The degraded fuel rod bundle from the second Phebus test (FPT1) was examined at ITU, Karlsruhe. Metallographic and microprobe
analysis of the degraded fuel pieces were carried out. The fuel samples from the upper bundle and cavity edge were porous
and had remnants of thick oxidised cladding adhering to them. Electron microprobe analysis line scans across the cladding-fuel
interface showed interdiffusion of U and Zr, with U diffusing down the grain boundaries of the oxidised cladding, while point
analyses revealed noticeable amounts of Zr (1.5–4.2 wt%) in the UO2 fuel. EPMA oxygen measurements revealed in the upper part of the bundle a superstoichiometry of x = 0.3–0.4 in UO
2 + x
, indicating that fuel fragments in this position had undergone considerable oxidation. X-ray diffraction of the corium pool
disclosed a deformed cubic fluorite lattice of UO2. The lattice parameter of a = 5.2984 ? was considerably reduced compared with pure, stoichiometric UO2 and was consistent with a lattice containing approximately 45 mol% ZrO2 that had undergone little oxidation. The corium’s nominal composition of (U0.5Zr0.5) O2 also corresponded to its observed single phase microstructure. 相似文献
14.
A. I. Shiyonok L. S. Kol’tsova N. L. Zaichenko V. S. Marevtsev A. O. Ait I. Yu. Sychev 《Russian Chemical Bulletin》2005,54(12):2899-2902
A photochemically bifunctional compound was obtained. Its molecule includes the spironaphthoxazine and dansylamino fragments.
This compound exhibits both photochromic and luminescent properties. Its spectroscopic characteristics were studied in different
solvents. The electronic systems of two constituent fragments do not interact with each other.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2802–2805, December, 2005. 相似文献
15.
V. E. Kuzmin I. S. Rublev D. V. Naroditskii E. V. Gapon 《Journal of Structural Chemistry》1995,36(5):798-802
New types of ligands for spherical ions have been designed as part of the molecular design strategy for supramolecular compounds.
In particular, symmetric conformers of macrocycles, built of −(CH2)n−O−(n=3,4,5) fragments, which envelope the spherical ion in a complementary way, have been constructed. Alos, new types of
“bracelentands” with different, “hardening” fragments are suggested. Using the molecular mechanics methods, the selectivity
of complex formation of the ligands with respect to alkaline metal ions has been investigated.
A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 5, pp. 879–883, September–October, 1995.
Translated by L. Smolina 相似文献
16.
Density functional PBE/TZ2p quantum chemical calculations of activated complexes and pathways of model catalytic transformations
of propane under the action of aluminum chloride-cobalt chloride ionic bimetallic complexes were carried out. The formation
of an intermediate with a broken C-C bond can occur on the cationic cluster CoAlCl4
+ characterized by the strongest coordination of propane molecule. The activation barrier to the reaction is ΔG = 25.0 kcal mol−1. Activation of alkane C-H bonds follows the alkyl pathway involving the formation of bimetallic alkyl complexes. The interaction
of activated hydrocarbon fragments bound to transition metal atoms in cobalt-chloroaluminate clusters can result in alkane
metathesis products (in this case, ethane and a polymetallic cluster containing an extendedchain alkyl radical). 相似文献
17.
18.
A. Yu. Kuznetsov A. B. Sobolev A. N. Varaksin O. A. Keda 《Journal of Structural Chemistry》1997,38(6):878-883
Results of electronic structure studies of the Ce3+ impurity in Lu2SiO5 crystals allowing for lattice polarization and relaxation are given. The calculations were performed by the embedded cluster
method combining the scattered wave and molecular static methods. The effect of lattice deformation induced by the defect
on the results of calculations is discussed.
Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 6, pp. 1046–1052, November–December, 1997. 相似文献
19.
S. P. Gavrish Ya. D. Lampeka P. S. Yaremov V. G. Il’in 《Theoretical and Experimental Chemistry》2007,43(1):54-58
The characteristic of the crystal lattice of the hydrate of a nickel complex with a tetradentate amide-containing ligand is
the presence of hexamers of the metal complex molecule, united by intermolecular hydrogen bonds which are retained during
adsorption and desorption of polar molecules. The lattice of this material is characterized by a definite lability which arises
during interaction with methanol.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 47–51, January–February, 2007. 相似文献
20.
The lattice model of associated solutions was used to calculate the concentration dependences of the chemical shifts of13C magnetic nuclei in the acrylamide molecule in water—DMSO solvent. Each pair of bonds between the acrylamide group containing
a magnetic nucleus and the neighboring solvent molecule was assumed to additively contribute to the change in the chemical
shift of the nucleus in question. The new approach affords the same accuracy in describing the experimental data at any ratios
of the solution components. It was shown that the chemical shifts and the excess heat of mixing of the water—DMSO binary solution
can be simultaneously described using the same set of energy parameters of the model. The model makes it possible to employ
experimental data on chemical shifts for studying intermolecular interactions in solutions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1983–1987, October, 1998. 相似文献