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931.
932.
Oleg V. Shishkin 《Journal of Molecular Structure》1996,385(3):318-214
Conformational flexibility of the 1,4-dihydropyridine ring in 4-aryl derivatives of the 2,6-dimethyl-3,5-dicarbmethoxy-1,4-dihydropyridine has been studied using the MM3 molecular mechanics method. Change of the C=C---C---C= endocyclic torsion angle of dihydrocycle in the range of 35° entails an increase of energy less than 1 kcal mol−1. The energy levels below 99% of the molecular population for each molecule were estimated. The interval of the torsion angle change for these regions is about 60°. 相似文献
933.
934.
Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen‐Dependent Photodynamic Cancer Therapy
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Dr. Oleg Babii Dr. Sergii Afonin Prof. Liudmyla V. Garmanchuk Dr. Viktoria V. Nikulina Tetiana V. Nikolaienko Olha V. Storozhuk Dmytro V. Shelest Dr. Olga I. Dasyukevich Prof. Liudmyla I. Ostapchenko Dr. Volodymyr Iurchenko Dr. Sergey Zozulya Prof. Anne S. Ulrich Prof. Igor V. Komarov 《Angewandte Chemie (International ed. in English)》2016,55(18):5493-5496
Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene‐derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light‐sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV‐generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light. 相似文献
935.
Design,Synthesis, and Application of an Optimized Monofluorinated Aliphatic Label for Peptide Studies by Solid‐State 19F NMR Spectroscopy
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Serhii O. Kokhan Andriy V. Tymtsunik Dr. Stephan L. Grage Dr. Sergii Afonin Dr. Oleg Babii Dr. Marina Berditsch Alexander V. Strizhak Dmytro Bandak Dr. Maxim O. Platonov Prof. Igor V. Komarov Prof. Anne S. Ulrich Dr. Pavel K. Mykhailiuk 《Angewandte Chemie (International ed. in English)》2016,55(47):14788-14792
A conformationally restricted monofluorinated α‐amino acid, (3‐fluorobicyclo[1.1.1]pentyl)glycine (F‐Bpg), was designed as a label for the structural analysis of membrane‐bound peptides by solid‐state 19F NMR spectroscopy. The compound was synthesized and validated as a 19F label for replacing natural aliphatic α‐amino acids. Calculations suggested that F‐Bpg is similar to Leu/Ile in terms of size and lipophilicity. The 19F NMR label was incorporated into the membrane‐active antimicrobial peptide PGLa and provided information on the structure of the peptide in a lipid bilayer. 相似文献
936.
Donchev AG Galkin NG Illarionov AA Khoruzhii OV Olevanov MA Ozrin VD Pereyaslavets LB Tarasov VI 《Journal of computational chemistry》2008,29(8):1242-1249
The recently introduced force field (FF) QMPFF3 is thoroughly validated in gas, liquid, and solid phases. For the first time, it is demonstrated that a physically well-grounded general purpose FF fitted exclusively to a comprehensive set of high level vacuum quantum mechanical data applied as it is to simulation of condensed phase provides high transferability for a wide range of chemical compounds. QMPFF3 demonstrates accuracy comparable with that of the FFs explicitly fitted to condensed phase data, but due to high transferability it is expected to be successful in simulating large molecular complexes. 相似文献
937.
Yan Z. Voloshin Oleg A. Varzatskii Alexander S. Belov Zoya A. Starikova Alexander V. Dolganov Tatiana V. Magdesieva 《Polyhedron》2008
Direct template macrocyclization of the three dimethylglyoxime molecules on the iron(II) ion and the capping of nonmacrocyclic K3CoDm3 tris-dimethylglyoximate with triethylantimony(V) derivatives led to the formation of triethylantimony-capped iron(II) and cobalt(III) clathrochelates. The complexes obtained have been characterized using elemental analysis, MALDI-TOF mass, IR, UV–Vis, 57Fe Mössbauer and 1H and 13C NMR spectroscopies, and X-ray crystallography. The influence of the nature of an encapsulated metal ion, the capping groups and the chelate fragments on a clathrochelate framework geometry is discussed. The cyclic voltammograms show oxidation and reduction waves assignable to Fe2+/3+ and Co2+/3+ couples of the encapsulated metal ion. 相似文献
938.
Palii AV Reu OS Ostrovsky SM Klokishner SI Tsukerblat BS Sun ZM Mao JG Prosvirin AV Zhao HH Dunbar KR 《Journal of the American Chemical Society》2008,130(44):14729-14738
In this article we report for the first time experimental details concerning the synthesis and full characterization (including the single-crystal X-ray structure) of the spin-canted zigzag-chain compound [Co(H2L)(H2O)]infinity [L = 4-Me-C6H4-CH2N(CPO3H2)2], which contains antiferromagnetically coupled, highly magnetically anisotropic Co(II) ions with unquenched orbital angular momenta, and we also propose a new model to explain the single-chain magnet behavior of this compound. The model takes into account (1) the tetragonal crystal field and the spin-orbit interaction acting on each Co(II) ion, (2) the antiferromagnetic Heisenberg exchange between neighboring Co(II) ions, and (3) the tilting of the tetragonal axes of the neighboring Co units in the zigzag structure. We show that the tilting of the anisotropy axes gives rise to spin canting and consequently to a nonvanishing magnetization for the compound. In the case of a strong tetragonal field that stabilizes the orbital doublet of Co(II), the effective pseudo-spin-1/2 Hamiltonian describing the interaction between the Co ions in their ground Kramers doublet states is shown to be of the Ising type. An analytical expression for the static magnetic susceptibility of the infinite spin-canted chain is obtained. The model provides an excellent fit to the experimental data on both the static and dynamic magnetic properties of the chain. 相似文献
939.
Schröder F Esken D Cokoja M van den Berg MW Lebedev OI Van Tendeloo G Walaszek B Buntkowsky G Limbach HH Chaudret B Fischer RA 《Journal of the American Chemical Society》2008,130(19):6119-6130
The gas-phase loading of [Zn4O(bdc)3] (MOF-5; bdc = 1,4-benzenedicarboxylate) with the volatile compound [Ru(cod)(cot)] (cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene) was followed by solid-state (13)C magic angle spinning (MAS) NMR spectroscopy. Subsequent hydrogenolysis of the adsorbed complex inside the porous structure of MOF-5 at 3 bar and 150 degrees C was performed, yielding ruthenium nanoparticles in a typical size range of 1.5-1.7 nm, embedded in the intact MOF-5 matrix, as confirmed by transmission electron microscopy (TEM), selected area electron diffraction (SAED), powder X-ray diffraction (PXRD), and X-ray absorption spectroscopy (XAS). The adsorption of CO molecules on the obtained Ru@MOF-5 nanocomposite was followed by IR spectroscopy. Solid-state (2)H NMR measurements indicated that MOF-5 was a stabilizing support with only weak interactions with the embedded particles, as deduced from the surprisingly high mobility of the surface Ru-D species in comparison to surfactant-stabilized colloidal Ru nanoparticles of similar sizes. Surprisingly, hydrogenolysis of the [Ru(cod)(cot)]3.5@MOF-5 inclusion compound at the milder condition of 25 degrees C does not lead to the quantitative formation of Ru nanoparticles. Instead, formation of a ruthenium-cyclooctadiene complex with the arene moiety of the bdc linkers of the framework takes place, as revealed by (13)C MAS NMR, PXRD, and TEM. 相似文献
940.
Csok Z Vechorkin O Harkins SB Scopelliti R Hu X 《Journal of the American Chemical Society》2008,130(26):8156-8157
A new pincer-type bis(amino)amine (NN2) ligand and its lithium and nickel complexes, including Ni(II) methyl, ethyl, and phenyl complexes, were synthesized. The Ni(II) alkyl complexes react cleanly with alkyl halides including chlorides to form C-C coupled products and Ni(II) halides. More interestingly, the Ni(II) alkyls undergo unprecedented reactions with CH2Cl2 and CHCl3 to cleave all the C-Cl bonds and replace them with C-C bonds. The reactions are highly selective and lead to the first efficient catalytic coupling of CH2Cl2 with alkyl Grignards. A conversion of 82% and a turnover number of 47 are achieved within minutes. Coupling of CD2Cl2 and 1,1-dichloro-3,3-dimethylbutane with nBuMgCl is also realized. Preliminary mechanistic study suggests a radical initiated process for these reactions. 相似文献