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401.
M. Ángeles Fuentes Dr. Bianca K. Muñoz Kane Jacob Dr. Laure Vendier Dr. Ana Caballero Prof. Michel Etienne Prof. Pedro J. Pérez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1327-1334
The complexes Fn‐TpAg(L) (Fn‐Tp=a perfluorinated hydrotris(indazolyl) borate ligand; L=acetone or tetrahydrofuran) efficiently catalyze the functionalization of non‐activated alkanes such as hexane, 2,3‐dimethylbutane, or 2‐methylpentane by insertion of CHCO2Et units (from N2CHCO2Et, ethyl diazoacetate, EDA) into their C? H bonds. The reactions are quantitative (EDA‐based), with no byproducts derived from diazo coupling being formed. In the case of hexane, the functionalization of the methyl C? H bonds has been achieved with the highest regioselectivity known to date with this diazo compound. This catalytic system also operates under biphasic conditions by using fluorous solvents such as Fomblin or perfluorophenanthrene. Several cycles of catalyst recovery and reuse have been performed, with identical chemo‐ and regioselectivities. 相似文献
402.
Structural and magnetic properties of nanocrystalline Fe75???x Co x Cu1 Nb3Si15B6 (x?=?0, 2, 5) alloys are reported using magnetic measurements X-ray diffraction, Mössbauer spectroscopy. Results show that: (1) for the specimens with x?=?0 reveal that the volume fraction of the nanograins and their grain diameter ranges between 56% and 80% and 10 and 18 nm, (2) annealing above 700°C apart from Fe3Si type nanocrystals, magnetically hard Fe3B, Fe23B phases also appear, leading to a sharp increase of the coercive field, (3) Co content and applied stress during annealing has considerable effect on relative permeability and stress induced anisotropy, which is perpendicular to the ribbon axis, Mössbauer spectroscopy also suggests changes in spin texture. 相似文献
403.
Dr. Conor T. Kelly Sean Dunne Dr. Irina A. Kühne Dr. Andrew Barker Dr. Kane Esien Dr. Solveig Felton Dr. Helge Müller-Bunz Dr. Yannick Ortin Prof. Grace G. Morgan 《Angewandte Chemie (International ed. in English)》2023,62(18):e202217388
Reversible proton-induced spin state switching of an FeIII complex in solution is observed at room temperature. A reversible magnetic response was detected in the complex, [FeIII(sal2323)]ClO4 ( 1 ), using Evans’ method 1H NMR spectroscopy which indicated cumulative switching from low-spin to high-spin upon addition of one and two equivalents of acid. Infrared spectroscopy suggests a coordination-induced spin state switching (CISSS) effect, whereby protonation displaces the metal-phenoxo donors. The analogous complex, [FeIII(4-NEt2-sal2323)]ClO4 ( 2 ), with a diethylamino group on the ligand, was used to combine the magnetic change with a colorimetric response. Comparison of the protonation responses of 1 and 2 reveals that the magnetic switching is caused by perturbation of the immediate coordination sphere of the complex. These complexes constitute a new class of analyte sensor which operate by magneto-modulation, and in the case of 2 , also yield a colorimetric response. 相似文献
404.
Lisaleigh Kane David A. Norman Scott A. White Mark W. Matsen Michael M. Satkowski Steven D. Smith Richard J. Spontak 《Macromolecular rapid communications》2001,22(5):281-296
While theoretical and experimental efforts have thoroughly addressed microphase‐ordered AB diblock copolymer blends with a parent homopolymer (hA or hB) or a second block copolymer, surprisingly few studies have considered comparable ABA triblock copolymers in the presence of hB or an AB diblock copolymer. In this study, we elucidate the roles of additive molecular weight and constraint by examining three matched series of miscible ABA/hB and ABA/AB blends. Self‐consistent field theory is employed to analyze molecular characteristics, e. g., segmental distributions, microdomain periods and midblock bridging fractions, as functions of blend composition. Predictions are compared to morphological characteristics discerned by transmission electron microscopy and small‐angle X‐ray scattering. The corresponding mechanical properties of these blends are measured by dynamic mechanical analysis. The results of this comprehensive work reveal that addition of hB swells the B‐lamellae of the ABA copolymer and has a generally deleterious effect on both the dynamic elastic modulus and midblock bridging fraction. In contrast, addition of a lamellar or cylindrical AB copolymer to the same ABA copolymer can promote an increase or decrease in lamellar period and bridging fraction, depending on relative block sizes. 相似文献