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51.
Dr. Sigurd Øien-Ødegaard Dr. Calliope Bazioti Dr. Evgeniy A. Redekop Dr. Øystein Prytz Prof. Karl Petter Lillerud Prof. Unni Olsbye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21581-21586
Herein, we report the discovery of a toroidal inorganic cluster of zirconium(IV) oxysulfate of unprecedented size with the formula Zr70(SO4)58(O/OH)146⋅x(H2O) (Zr70), which displays different packing of ring units and thus several polymorphic crystal structures. The ring measures over 3 nm across, has an inner cavity of 1 nm and displays a pseudo-10-fold rotational symmetry of Zr6 octahedra bridged by an additional Zr in the outer rim of the ring. Depending on the co-crystallizing species, the rings form various crystalline phases in which the torus units are connected in extended chain and network structures. One phase, in which the ring units are arranged in layers and form one-dimensional channels, displays high permanent porosity (BET surface area: 241 m2 g−1), and thus demonstrates a functional property for potential use in, for example, adsorption or heterogeneous catalysis. 相似文献
52.
53.
Aram Arutyunov Valeriano Antunes de Oliveira Fernando Lobo Pereira Evgeniy Zhukovskiy 《Applicable analysis》2015,94(1):129-143
In the paper, the set-valued covering mappings are studied. The statements on solvability, solution estimates, and well-posedness of inclusions with conditionally covering mappings are proved. The results obtained are applied to the investigation of differential inclusions unsolved for the unknown function. The statements on solvability, solution estimates, and well-posedness of these inclusions are derived. 相似文献
54.
Evgeniy V. Ivanov 《The Journal of chemical thermodynamics》2010,42(12):1458-1464
Densities of solutions of H2O and D2O in nitromethane, with the solute mole fractions ranging up to 0.03, were measured with an error of 1.5 · 10−5 cm3 · mol−1 at (278.15, 288.15, 298.15, 308.15, and 318.15) K using a vibrating-tube densimeter. Apparent and partial volumes and isobaric expansibilities (down to the infinite dilution) of water isotopologues were calculated. The temperature-dependent behavior of D2O–H2O solute isotope effects on the molar quantities studied were described taking into account the structure- and interaction-related peculiarities of the dissolving medium in question. 相似文献
55.
Densities of (water + hexamethylphosphoric triamide) in the entire mole-fraction composition at five temperatures, from (288.15 to 308.15) K, and atmospheric pressure were measured by using a magnetic float densimeter with an error of ±1.1 · 10?5 g · cm?3. Excess molar volumes of the mixtures and apparent molar volumes of the components (down to their infinite dilution) were calculated. The volumetric effects of mixing being very large in magnitude present negative deviations from ideality and become decreasingly negative with increasing temperature. The apparent molar volume of organic co-solvent displays a clearly pronounced minimum in the water-rich region at all the temperatures studied. It has been shown that there is a thermodynamically substantiated interrelation between volume and enthalpy (heat capacity) properties of the mixtures considered. 相似文献
56.
Prof. Dr. Danil N. Dybtsev Maxim P. Yutkin Dr. Denis G. Samsonenko Prof. Dr. Vladimir P. Fedin Dr. Alexey L. Nuzhdin Andrey A. Bezrukov Prof. Konstantin P. Bryliakov Prof. Evgeniy P. Talsi Prof. Rodion V. Belosludov Prof. Hiroshi Mizuseki Prof. Yoshiyuki Kawazoe Dr. Oleg S. Subbotin Vladimir R. Belosludov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(34):10348-10356
Two new, homochiral, porous metal–organic coordination polymers [Zn2(ndc){(R)‐man}(dmf)]?3DMF and [Zn2(bpdc){(R)‐man}(dmf)]?2DMF (ndc=2,6‐naphthalenedicarboxylate; bpdc=4,4′‐biphenyldicarboxylate; man=mandelate; dmf=N,N′‐dimethylformamide) have been synthesized by heating ZnII nitrate, H2ndc or H2bpdc and chiral (R)‐mandelic acid (H2man) in DMF. The colorless crystals were obtained and their structures were established by single‐crystal X‐ray diffraction. These isoreticular structures share the same topological features as the previously reported zinc(II) terephthalate lactate [Zn2(bdc){(S)‐lac}(dmf)]?DMF framework, but have larger pores and opposite absolute configuration of the chiral centers. The enhanced pores size results in differing stereoselective sorption properties: the new metal–organic frameworks effectively and stereoselectively (ee up to 62 %) accommodate bulkier guest molecules (alkyl aryl sulfoxides) than the parent [Zn2(bdc){(S)‐lac}(dmf)]?DMF, while the latter demonstrates decent enantioselectivity toward precursor of chiral anticancer drug sulforaphane, CH3SO(CH2)4OH. The new homochiral porous metal–organic coordination polymers are capable of catalyzing a highly selective oxidation of bulkier sulfides (2‐NaphSMe (2‐C10H7SMe) and PhSCH2Ph) that could not be achieved by the smaller‐pore [Zn2(bdc){(S)‐lac}(dmf)]?DMF. The sorption of different guest molecules (both R and S isomers) into the chiral pores of [Zn2(bdc){(S)‐lac}(dmf)]?DMF was modeled by using ab initio calculations that provided a qualitative explanation for the observed sorption enantioselectivity. The high stereo‐preference is accounted for by the presence of coordinated inner‐pore DMF molecule that forms a weak C? H???O bond between the DMF methyl group and the (S)‐PhSOCH3 sulfinyl group. 相似文献
57.
de Groot M Buma WJ Gromov EV Burghardt I Köppel H Cederbaum LS 《The Journal of chemical physics》2006,125(20):204303
The low-lying excited singlet states of paravinyl phenol (pVP) are investigated experimentally and theoretically paying attention to their similarity to excited states of paracoumaric acid, the chromophore of the photoactive yellow protein (PYP). Resonance enhanced multiphoton ionization and laser induced fluorescence spectroscopic techniques are employed to obtain supersonically cooled, vibrationally resolved excitation and emission spectra related to the lowest (1)A'(V') excited state of pVP. Comprehensive analyses of the spectral structures are carried out by means of the equation-of-motion coupled cluster singles and doubles and time dependent density functional theory methods in combination with the linear vibronic coupling model and Franck-Condon calculations. The assignments of the spectral patterns are given, mostly in terms of excitations of totally symmetric modes. Weak activity of the non-totally-symmetric modes indicates low probability of photochemical processes in the Franck-Condon region of the (1)A'(V') state. The second (1)A'(V) and third (1)A" (Ryd) excited states of pVP are characterized with regard to their electronic structure, properties, and effects of geometry relaxations. The lengthening of the double bond relevant to the trans-cis isomerization of the PYP chromophore is found for the (1)A'(V) state. A possibility of photochemical processes and strong vibronic interactions in this state can be expected. The theoretical results for the (1)A"(Ryd) state predict that dissociation with respect to the O-H bond is possible. 相似文献
58.
Evgeniy A. Ivanov Sergey I. Reshetnikov Mikhail V. Sidyakin Anatoliy N Startsev 《Reaction Kinetics and Catalysis Letters》2006,88(2):325-332
Summary An unsteady-state kinetic model of both benzene hydrogenation (HDA) and thiophene hydrogenolysis (HDS) on a sulfide hydrotreating
catalyst Ni-Mo/Al2O3 has been developed. The model adequately describes experimental data obtained at the pressure 2 MPa, temperature 573 K and
at various contact times and ratios of benzene/thiophene. The model is based on the assumption that the catalyst surface contains
only one type of active sites, i.e., Ni atoms in the sulfide bimetallic species, which are responsible for both hydrogenolysis and hydrogenation reactions. 相似文献
59.
Evgeniya A. Stepnova Tatiana A. Babushkina Evgeniy V. Vorontsov Sergey A. Lopatin 《European Polymer Journal》2007,43(6):2414-2421
Regioselective quaternization of chitosan and its amphiphilic derivatives has been carried out by means of reaction with betaine in the presence of the coupling reagent 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) in aqueous media at pH 5.5 ± 0.5. This reaction results in preparation of N-/(trimethylammonio)acetyl/chitosan chloride and its amphiphilic derivatives. The degree of quaternization increases with increasing EEDQ/chitosan ratio and is partly accompanied by N-ethoxycarbonylation. That side-product formation can be minimized by increasing betaine/EEDQ ratio. 相似文献
60.