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61.
Stephenson AW Partridge AC Filichev VV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(22):6227-6238
A synthetic methodology for the synthesis of various β-pyrrolic-functionalised porphyrins and their covalent attachment to 2'-deoxyuridine and DNA is described. Palladium(0)-catalysed Sonogashira and copper(I)-catalysed Huisgen 1,3-dipolar cycloaddition reactions were used to insert porphyrins into the structure of 2'-deoxyuridine and DNA. Insertion of a porphyrin into the middle of single-stranded CT oligonucleotides possessing a 5'-terminal run of four cytosines was shown to trigger the formation of pH- and temperature-dependent i-motif structures. Porphyrin insertion also led to the aggregation of single-stranded purine-pyrimidine sequences, which could be dissociated by heating at 90 °C for 5 min. Parallel triplexes and anti-parallel duplexes were formed in the presence of the appropriate complementary strand(s). Depending on the modification, porphyrins were placed in the major and minor grooves of duplexes and were used as bulged intercalating insertions in duplexes and triplexes. In general, the thermal stabilisation of parallel triplexes possessing porphyrin-modified triplex-forming oligonucleotide (TFO) strands was observed, whereas anti-parallel duplexes were destabilised. These results are compared and discussed on the basis of the results of molecular modelling calculations. 相似文献
62.
Nina I. Giricheva Georgiy V. Girichev Yulia S. Medvedeva Sergey N. Ivanov Anna V. Bardina Vyacheslav M. Petrov 《Structural chemistry》2011,22(2):373-383
A combined gas-phase electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pvtz, MP2/cc-pvtz) study of molecular
structure of 2-nitrobenzenesulfonamide (2-NBSA) was carried out. Quantum chemical calculations showed that 2-NBSA has four
conformers, two of which are stabilized by intramolecular hydrogen bond. The latter (with the S–N bond in a close to orthogonal
position around the phenyl ring and differing from each other by staggered or eclipsed positions of the N–H and S=O bonds
in the SO2NH2 group) presented in a saturated vapor over 2-NBSA at T = 433 (3) K in commensurable amounts. Experimental internuclear distances (Ǻ) for the staggered conformer are (?): r
h1(C–H)av. = 1.071(9), r
h1(C–C)av. = 1.390(4), r
h1(C–S) = 1.789(8), r
h1(S=O)av. = 1.427(6), r
h1(S–N) = 1.644(6), r
h1(N–O)av. = 1.221(4), r
h1(C′–N) = 1.487(8), r
h1(N–H)av. = 1.014. Calculations at B3LYP/cc-pvtz level were performed to determine the structure and the energies of the transition
states between conformers. It was shown that the conformer structures of free molecule differ from those of a molecule stabilized
by intermolecular hydrogen bonds in a crystal. Influence of a substituent X (X = –CH3, –NO2) on conformational features of the ortho-substituted benzenesulfonamide was established. 相似文献
63.
A square matrix is nonderogatory if its Jordan blocks have distinct eigenvalues. We give canonical forms for
- •
- nonderogatory complex matrices up to unitary similarity, and
- •
- pairs of complex matrices up to similarity, in which one matrix has distinct eigenvalues.
64.
Oleg S. Radchenko Elena N. Sigida Nadezhda N. Balaneva Pavel S. Dmitrenok Vyacheslav L. Novikov 《Journal of heterocyclic chemistry》2011,48(1):209-214
Unusual course of the reaction was revealed on the oxidation of functionally substituted acridine containing the activated methyl groups by well‐known oxidants, such as selenous acid and selenium(IV) oxide. Treatment of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine ( 5 ) with an excess of H2SeO3 in boiling ethanol gave a mixture of the normal reaction products, 2‐methoxy‐4‐methyl‐1‐nitro‐9‐formylacridine ( 11 ) (isolated yield 29%) and 2‐methoxy‐4‐methyl‐1‐nitroacridine‐9‐carboxylic acid ( 12 ) (36%), together with an abnormal product, 3‐methoxy‐5‐methyl‐1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one ( 13 ) (21%), which is the first example of a new seleno‐containing ring system. With the use of SeO2 the yield of selenolactone 13 was much lower. J. Heterocyclic Chem., 2011. 相似文献
65.
David Fuks Dina Shapiro Arnold Kiv Vyacheslav Golovanov Chung‐Chiun Liu 《International journal of quantum chemistry》2011,111(9):1902-1906
A slab approach in the framework of ab initio calculations was applied to study surface electronic states in In2O3 crystal. Density functional theory (DFT) calculations were carried out employing the WIEN 2k code and using the full potential method with Augmented Plane Waves + local orbitals (APW+lo) formalism. Total and partial DOS (Density of States) were calculated for In and O atoms in two upper (110) surface layers. Comparison of total and partial DOS allowed determining a contribution of electronic states of different In and O surface atoms into formation of surface electronic spectra and corresponding chemical bonds. A dominant ionic character of chemical bonds in In2O3 is found. Calculations were performed for three slab models with different geometry parameters. It was shown that an optimal ratio between the whole vertical size of a supercell and the vertical size of atomic cluster has to be chosen. The size of vacuum region in the slab model influences significantly on the reliability of calculated characteristics of the surface electronic structure. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
66.
Plyusnin VF Kolomeets AV Grivin VP Larionov SV Lemmetyinen H 《The journal of physical chemistry. A》2011,115(10):1763-1773
Laser pulse photolysis was used to study the nature and reactions of intermediates in the photochemistry of the flat dithiocarbamate complex Cu(Et(2)dtc)(2) in CCl(4). A nanosecond laser pulse (355 nm) is shown to induce intermediate absorption bands of bivalent copper complex whose coordination sphere contains a dithiocarbamate radical Et(2)dtc(?) and a chloride ion at the axial position ([(Et(2)dtc)Cu(Et(2)dtc(?))Cl(a)]). At room temperature during some microseconds after the laser pulse, this intermediate interacts with the initial complex to form presumably a dimer [Cu(2)(Et(2)dtc)(3)(Et(2)dtc(?))Cl]. The latter vanishes in the second-order reaction. Analysis of kinetic and spectral features gives the arguments for the formation of a cluster [Cu(2)(Et(2)dtc)(3)Cl-tds-Cu(2)(Et(2)dtc)(3)Cl], which produces a new absorption band at 345 nm. The cluster decomposes in ~5 ms into final products, a binuclear complex [Cu(2)(Et(2)dtc)(3)Cl] and tetraethylthiuramdisulfide (Et(4)tds). 相似文献
67.
We consider a spectral problem generated by the Stieltjes string equation on a metric figure-of-eight graph and the corresponding
inverse problem which is stated as follows. Values of the point masses located on one of the loops and the lengths of subintervals
on it are given together with the spectrum of the spectral problem on the whole graph, the total length of the second loop
and the length of the first subinterval on it, and a certain constant. Values of the masses and the lengths of subintervals
on the second loop are to be found. Conditions sufficient for such a problem to be solvable are given in the implicit form.
An algorithm for recovering the masses and the subintervals on the second loop is proposed. 相似文献
68.
Wolfgang Bock Vyacheslav Futorny Mikhail Neklyudov 《Journal of Pure and Applied Algebra》2021,225(3):106535
A realization by linear vector fields is constructed for any Lie algebra which admits a biorthogonal system and for its any suitable representation. The embedding into Lie algebras of linear vector fields is in analogue to the classical Jordan—Schwinger map. A number of examples of such Lie algebras of linear vector fields is computed. In particular, we obtain examples of the twisted Heisenberg-Virasoro Lie algebra and the Schrödinger-Virasoro Lie algebras among others. More generally, we construct an embedding of an arbitrary locally convex topological algebra into the Cuntz algebra. 相似文献
69.
Using the factorization method, we construct finite-difference Schrödinger operators (Jacobi matrices) whose discrete spectra are composed from independent arithmetic, or geometric series. Such systems originate from the periodic, orq-periodic closure of a chain of corresponding Darboux transformations. The Charlier, Krawtchouk, Meixner orthogonal polynomials, theirq-analogs, and some other classical polynomials appear as the simplest examples forN = 1 andN = 2 (N is the period of closure). A natural generalization involves discrete versions of the Painlevé transcendents.On leave of absence from the Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia. 相似文献
70.