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91.
92.
Self‐Assembly of a Giant Tetrahedral 3 d–4 f Single‐Molecule Magnet within a Polyoxometalate System 下载免费PDF全文
Dr. Masooma Ibrahim Dr. Valeriu Mereacre Dr. Nicolas Leblanc Prof. Wolfgang Wernsdorfer Dr. Christopher E. Anson Prof. Annie K. Powell 《Angewandte Chemie (International ed. in English)》2015,54(51):15574-15578
A giant tetrahedral heterometallic polyoxometalate (POM) [Dy30Co8Ge12W108O408(OH)42(OH2)30]56?, which shows single‐molecule magnet (SMM) behavior, is described. This hybrid contains the largest number of 4f ions of any polyoxometalate (POM) reported to date and is the first to incorporate two different 3d–4f and 4f coordination cluster assemblies within same POM framework. 相似文献
93.
Corrigendum: Crowdsourcing Natural Products Discovery to Access Uncharted Dimensions of Fungal Metabolite Diversity 下载免费PDF全文
94.
Development of standards for reliable surface analyses by ISO technical committee 201 on surface chemical analysis 下载免费PDF全文
C. J. Powell R. Shimizu K. Yoshihara S. Ichimura 《Surface and interface analysis : SIA》2015,47(1):127-134
The need for reliable surface analyses together with quality‐management requirements for analytical laboratories led the International Organization for Standardization (ISO) to form its Technical Committee (TC) 201 on Surface Chemical Analysis in 1991. This article describes the organization of TC 201, the strategies that have been found useful for identifying and assessing possible projects for new international standards, and the 57 international standards and other documents prepared to date by TC 201. Standards have now been developed for Auger‐electron spectroscopy, glow‐discharge spectroscopy, various types of scanning probe microscopy, secondary‐ion mass spectrometry, sputter‐depth profiling, total‐reflection X‐ray fluorescence spectroscopy, X‐ray photoelectron spectroscopy, and X‐ray reflectometry. In addition, standards have been developed with definitions of terms used in surface chemical analysis; the handling, preparation of specimens for surface analysis; information and data‐transfer formats; and methods for determining the lateral resolution of beam‐based methods of surface analysis. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
95.
G. D. Galvin J. F. Hutton B. Jones H. Naylor M. C. Phillips G. Powell E. Wyn-Jones 《Rheologica Acta》1973,12(4):519-523
Summary We review the difficulties encountered in the design and operation of apparatus for rheological studies on liquids at pressures up to 900 MN m–2 and temperatures from –30 to 120°C. Such rheological information is required in connection with elastohydrodynamic lubrication in which high pressures and shear rates are encountered.With 3 figures 相似文献
96.
97.
Ashok K. VishwakarmaPrasanna S. Ghalsasi Arulsamy NavamoneyYanhua Lan A.K. Powell 《Polyhedron》2011,30(9):1565-1570
Compounds of the general formula A2CuCl4, (where A = 4-fluoroanilinium (1) and 4-chloroanilinium (2)) were prepared, structurally characterized and their thermal and magnetic properties studied. These compounds have a layered structure, distorted perovskite, where layers of CuCl42− are sandwiched between a 4-haloanilinium cation bilayer. A single crystal X-ray diffraction study on (4-fluoroanilinium)2CuCl4, (1), shows that it crystallizes in the monoclinic P21/c space group with cell dimensions a = 15.5113(5) Å, b = 7.3788(2) Å, c = 7.0929(2) Å, β = 99.004(2)°, volume 801.81(4) Å3 at 150 K. Compound 2, (4-chloroanilinium)2CuCl4, crystallizes isostructurally to 1 at RT, but at 150 K it adopts the Pccn space group. This structural transition for 2 is reversible, and has been observed using Differential Scanning Calorimetric (DSC) measurements. The dc-magnetic studies using a SQUID magnetometer suggest that both compounds are soft ferromagnets and show an onset of long range magnetic ordering below 9 K. The ac-susceptibility measurements confirm the presence of this ferromagnetic ordering in both the compounds. 相似文献
98.
An improved methodology for the synthesis of substituted pyrido[2,3-d]pyrimidinediones from 6-aminouracils and the corresponding enaminone has been developed which provides high yields via an operationally simple process. The method has been extended to encompass a range of electron-rich enaminones, a substrate class that does not perform well under the standard conditions. 相似文献
99.
100.
Stuiber S Wu G Nehrkorn J Dreiser J Lan Y Novitchi G Anson CE Unruh T Powell AK Waldmann O 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(33):9094-9106
The synthesis, crystal structure and magnetic characterisation by magnetisation and inelastic neutron scattering (INS) of a mixed-valent Mn(10) supertetrahedral aggregate [Mn(III)(6)Mn(II)(4)(μ(4)-O)(4)(μ(3)-N(3))(3)(μ(3)-Br)(Hmpt)(6)(Br)]Br(0.7)(N(3))(0.3)·2MeOH·3MeCN (1) (H(3)mpt=3-methylpentan-1,3,5-triol) is reported. The magnetic core of the molecule can be described as an octahedron of six S=2 Mn(III) ions with four faces, each capped by a S=5/2 Mn(II) ion such as to form the supertetrahedron. Unlike most related complexes, the molecular symmetry is slightly reduced from approximately T(d) to C(3). The magnetic data reveal a total spin of S=22 in the ground state due to ferromagnetic exchange couplings within the molecule. The combined INS and magnetic data permits the accurate determination of the exchange coupling constants. Two types are found. The couplings between the Mn(III) ions in the inner octahedron are characterised by J(a)=18.4(3) K, whereas the couplings between the apical Mn(II) ions to the neighbouring Mn(III) ions are given by J(b)=7.3(2) K. The significantly larger coupling strength J(a) as compared to J(b), and the near-T(d) symmetry have profound consequences on the energy spectrum, which are discussed and carefully analysed. In particular, the observed INS spectra can consistently be reproduced by a simplified model in which the inner octahedron is replaced by one large spin of length S(0)=12. This model provides intuitive insight into the structure of the magnetic spectrum. Additionally, the magnetic excitations at low temperature are analysed within the frame of ferromagnetic linear spin-wave theory, which permits an analytical calculation of the energy levels. For ferromagnetic clusters, a close analogy to the Hückel method of electronic structure calculation can be drawn, which allows one to grasp the results of the spin-wave theory or the magnetic excitation spectrum, respectively, in a chemical language. 相似文献