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61.
CHEN Man-Sheng DENG Yi-Fang ZHANG Chun-Hua KUANG Dai-Zhi② FENG Yong-Lan PENG Yun-Lin 《结构化学》2007,26(2):219-223
A new manganese coordination polymer 1, [Mn(H2O)4(L)]n(ClO4)2n·2nH2O·3nL (L = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene), has been synthesized and structurally characterized. The crystal structure was determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group Pn with a = 13.9176(8), b = 15.4754(9), c = 15.9670(9) , β = 99.5010(10)o, V = 3391.8(3) 3, Z = 2, C56H68Cl2MnN16O14 , Mr = 1315.10, Dc = 1.288 g/cm3, μ = 0.344 mm-1, F(000) = 1374, R = 0.0733 and wR = 0.2035. In the crystal the manganese atom is six-coordinated by two nitrogen atoms from 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene and four oxygen atoms from water molecules, completing an octahedral geometry. The title complex exhibits a novel supramolecular layer architecture sustained by the concurrence of coordination bonds, hydrogen bonds, and π-π stacking interactions. 相似文献
62.
63.
A. M. Churakov A. Yu. Tyurin E. L. Goncharova S. L. Ioffe Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》1995,44(5):890-896
The addition of 1-aryl-2-bromodiazene 1-oxides to olefins yields 1-aryl-2-(2-bromoalkyl)diazene 1-oxides (4). A radical mechanism of the reaction has been suggested. Compounds4 decompose to give bromohydrazones of formaldehyde and aldehydes. The structural factors that affect the rate of this process are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 917–923, May, 1995.The work was carried out in the Scientific Educational Center of the Institute of Organic Chemistry of the RAS with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461). 相似文献
64.
A hydrothermal cleavage-decomposition mechanism was used to synthesize single-crystal α-Mn2O3 nanorods at 160 °C for 16 h using KMnO4 as manganese source and CTAB as reducing regent. The as-synthesized products were characterized by powder X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and infrared spectrum. The results indicate that the reaction temperature is a crucial factor for the formation of α-Mn2O3 nanorods. These nanorods exhibit single-crystal nature, and have an average diameter of 36 nm and lengths of up to 1 μm. Based on our experimental results, a hydrothermal cleavage-decomposition mechanism has been proposed on the formation of α-Mn2O3 nanorods. 相似文献
65.
As bio‐inspired chemical model of the oxygen‐evolving complex (OEC) in photosystem II, a new tyrosine‐modified corrole ligand 3 and its high‐valent copper and manganese complexes 3a and 3b were synthesized and characterized. The copper complexes 1a and 2a of corrole 1 and 2 were also prepared for comparison. The emission property indicates that the emission of ligands 2 and 3 is located at 670 nm, but no emission is observed for their metal complexes due to its suppression by the metal center. The electrochemical study shows that 3a might dimerize at the first two reversible oxidations, a behavior which was not observed in the case of 1a and 2a . The corrolato manganese(IV) complex 3b shows one reversible reduction and one quasireversible oxidation at ?0.17 and 0.77 V vs. Ag/Ag+, respectively. 相似文献
66.
Marina Lulla Jelena Asari Jaan Aarik Kaupo Kukli Raul Rammula Unto Tapper Eero Kauppinen Väino Sammelselg 《Mikrochimica acta》2006,155(1-2):195-198
Quantitative electron probe microanalysis of highly insulating materials is a complicated problem, partially solved by coating
samples with grounded thin conductive layers or using novel scanning electron microscopy (SEM) techniques, such as low-voltage
and/or variable pressure SEM. In this work, some problems of quantitative X-ray microanalysis of thin HfO2 films, in particular the possibility to determine mass thickness correlated to the density of the layer material, are discussed.
For comparison, Al2O3, Ta2O5 and TiO2 films grown onto both semiconductive Si and insulating quartz substrates were also analysed. All the films studied were synthesized
by atomic layer deposition method. 相似文献
67.
In this article we study the effect of energetic heterogeneity of a crystalline surface on the adsorption of hydrogen ions (protons) from the liquid phase. In particular, we examine the influence of the shape of the adsorption energy distribution on the equilibrium isotherms of hydrogen ions. To that purpose, a few popular distribution functions, including rectangular, exponential, and asymmetric Gaussian are considered. Additionally, multimodal distribution functions, which may correspond to the adsorption on different crystal planes of the oxide, are also used. Lateral interactions between adsorbed charges are modeled using the potential function proposed by Borkovec et al., which accounts also for polarization of the liquid medium. The results presented here are obtained using both Monte Carlo (MC) simulations and theoretical calculations involving Mean Field Approximation (MFA). They indicate that increased energetic heterogeneity of the adsorbing surface may, in general, considerably change the behavior of the adsorption isotherms, regardless of the assumed distribution function. It is also shown that the predictions of the proposed theory are consistent with the data obtained from the MC simulations. 相似文献
68.
S. F. Malysheva N. K. Gusarova N. A. Belogorlova A. V. Afonin S. N. Arbuzova B. A. Trofimov 《Russian Chemical Bulletin》1997,46(10):1799-1801
Diorganylvinylphosphine oxides were synthesized in 31–38% yields on heating (50°C) diorganylphosphine oxides with vinyl sulfoxides
or divinyl sulfone in the presence of KOH.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1895–1896, October, 1997. 相似文献
69.
The surface and materials science of tin oxide 总被引:3,自引:0,他引:3
The study of tin oxide is motivated by its applications as a solid state gas sensor material, oxidation catalyst, and transparent conductor. This review describes the physical and chemical properties that make tin oxide a suitable material for these purposes. The emphasis is on surface science studies of single crystal surfaces, but selected studies on powder and polycrystalline films are also incorporated in order to provide connecting points between surface science studies with the broader field of materials science of tin oxide. The key for understanding many aspects of SnO2 surface properties is the dual valency of Sn. The dual valency facilitates a reversible transformation of the surface composition from stoichiometric surfaces with Sn4+ surface cations into a reduced surface with Sn2+ surface cations depending on the oxygen chemical potential of the system. Reduction of the surface modifies the surface electronic structure by formation of Sn 5s derived surface states that lie deep within the band gap and also cause a lowering of the work function. The gas sensing mechanism appears, however, only to be indirectly influenced by the surface composition of SnO2. Critical for triggering a gas response are not the lattice oxygen concentration but chemisorbed (or ionosorbed) oxygen and other molecules with a net electric charge. Band bending induced by charged molecules cause the increase or decrease in surface conductivity responsible for the gas response signal. In most applications tin oxide is modified by additives to either increase the charge carrier concentration by donor atoms, or to increase the gas sensitivity or the catalytic activity by metal additives. Some of the basic concepts by which additives modify the gas sensing and catalytic properties of SnO2 are discussed and the few surface science studies of doped SnO2 are reviewed. Epitaxial SnO2 films may facilitate the surface science studies of doped films in the future. To this end film growth on titania, alumina, and Pt(1 1 1) is reviewed. Thin films on alumina also make promising test systems for probing gas sensing behavior. Molecular adsorption and reaction studies on SnO2 surfaces have been hampered by the challenges of preparing well-characterized surfaces. Nevertheless some experimental and theoretical studies have been performed and are reviewed. Of particular interest in these studies was the influence of the surface composition on its chemical properties. Finally, the variety of recently synthesized tin oxide nanoscopic materials is summarized. 相似文献
70.
Kang Y Zyryanov GV Rudkevich DM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(6):1924-1932
The use of simple calix[4]arenes for chemical conversion of NO2/N2O4 gases is demonstrated in solution and in the solid state. Upon reacting with these gases, calixarenes 1 encapsulate nitrosonium (NO+) cations within their cavities with the formation of stable calixarene-NO+ complexes 2. These complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. Complexes 2 were effectively used for nitrosation of secondary amides 5, including chiral derivatives. Unique size-shape selectivity was observed, allowing for exclusive nitrosation of less crowded N-Me amides 5 a-e (up to 95 % yields). Bulkier N-Alk (Alk>Me) substrates 5 did not react due to the hindered approach to the encapsulated NO+ reagents. Robust, silica gel based calixarene material 3 was prepared, which reversibly traps NO2/N2O4 with the formation of NO+-storing silica gel 4. With material 4, similar size-shape selectivity was observed for nitrosation. The N-Me-N-nitroso derivatives 6 d,e were obtained with approximately 30 % yields, while bulkier amides were nitrosated with much lower yields (<8 %). Enantiomerically pure encapsulating reagent 2 d was tested for nitrosation of racemic amide 5 t, showing modest but reproducible stereoselectivity and approximately 15 % ee. Given high affinity to NO+ species, which can be generated by a number of NOX gases, these supramolecular reagents and materials may be useful for NOX entrapment and separation in the environment and biomedical areas. 相似文献