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991.
992.
Hiroki Fukunaga Dr. Wataru Kosaka Honoka Nemoto Dr. Kouji Taniguchi Dr. Shogo Kawaguchi Dr. Kunihisa Sugimoto Prof. Dr. Hitoshi Miyasaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16755-16766
The insertion of “sandwiched spins” between magnetic layers could efficiently affect the interlayer magnetic correlations, but doing so increases the complexity in the interlayer spin alignment because of competition between the inserted spin-layer interaction JNNI and the interlayer through-space interaction JNNNI if the magnitude of JNNI is of the same order as JNNNI with reciprocal signs of the respective interactions. Herein, systematic tuning of the magnetic phase variations by JNNI and JNNNI in two kinds of metal-variable isostructural series of supramolecular pillared layer magnets [MCp*2][{Ru2II,II(2,3,5,6-F4CO2)4}2(TCNQ)] ⋅ 2 DCE (M=Co, Fe, Cr; 2,3,5,6-F4PhCO2−=2,3,5,6-tetrafluorobenzoate; TCNQ=7,7,8,8-tetracyano-p-quinodimethane; DCE=1,2-dichloroethane) and their DCE-free series, in which [MCp*2]+ (Cp*=η5-C5Me5) species with S=0, 1/2, and 3/2 for M=Co, Fe, Cr, respectively, are sandwiched between ferrimagnetic layers of [{Ru2}2(TCNQ)]−, is demonstrated. The results showed that the flexible magnetic natures of these magnets are changeable in dependence on JNNI and JNNNI, as well as on interlayer inserted spins M. 相似文献
993.
994.
Yusuke Hashimoto Munetaka Taguchi Shun Fukami Hiroki Momono Tomohiro Matsushita Hiroyuki Matsuda Fumihiko Matsui Hiroshi Daimon 《Surface and interface analysis : SIA》2019,51(1):115-119
Fe 2p core-level photoelectron spectra of magnetite were measured using soft X-ray and hard X-ray, and its emission angle dependence was investigated. The photoelectron diffraction pattern from different atomic sites differs because the atomic arrangement surrounding each site is different. By selecting the forward-focusing-peak (FFP) directions characteristic to each atomic site and measuring the kinetic energy dependence of the FFP intensities at the Fe 2p core-level range, we succeed in detecting the variation of the peak intensity of Fe 2p core-level spectra at different emission directions. This result, consistent with recent results, suggests that the lower-binding-energy peak of the Fe 2p core-level spectrum may be assigned as the B site component. 相似文献
995.
Hiroki Ishikawa Naohiro Uemura Rei Saito Prof. Yasushi Yoshida Prof. Takashi Mino Prof. Yoshio Kasashima Prof. Masami Sakamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9758-9763
Dynamic enantioselective crystallization enabled the chiral symmetry breaking of two spiropyrans and one spirooxazine. The three spiro compounds afforded racemic conglomerate crystals, and easily racemized in alcoholic solution without irradiation. Optically pure enantiomorphic crystals were obtained by vapor-diffusion crystallization or attrition-enhanced deracemization (Viedma ripening). Their absolute configurations were determined by single-crystal X-ray analysis and each enantiomorphic crystal was correlated with its solid-state circular dichroism (CD) spectrum. 相似文献
996.
997.
Comparative evaluation of new Cookson‐type reagents for LC/ESI‐MS/MS assay of 25‐hydroxyvitamin D3 in neonatal blood samples 下载免费PDF全文
Shoujiro Ogawa Hiroki Kittaka Kenta Shinoda Satoshi Ooki Akiho Nakata Tatsuya Higashi 《Biomedical chromatography : BMC》2016,30(6):938-945
The screening of vitamin D deficiency in neonatal infants, which is based on the blood 25‐hydroxyvitamin D3 [25(OH)D3] quantification, is important for the early detection, diagnosis and health risk assessment of several diseases. In this study, two new Cookson‐type reagents, 4‐(4‐diethylaminophenyl)‐1,2,4‐triazoline‐3,5‐dione (DEAPTAD) and 4‐(6‐quinolyl)‐1,2,4‐triazoline‐3,5‐dione, were designed and synthesized, then compared with the previous reagents, 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione (PTAD) and 4‐(4‐dimethylaminophenyl)‐1,2,4‐triazoline‐3,5‐dione (DAPTAD), in terms of sensitivity and specificity in the assay of 25(OH)D3 in neonatal blood samples by liquid chromatography/electrospray ionization–tandem mass spectrometry. Among the reagents, DEAPTAD was found to be the most promising. The limit of detection (0.38 fmol on the column) of the DEAPTAD‐derivatized 25(OH)D3 was 60 and 2 times lower than those of the intact 25(OH)D3 and the PTAD derivative, respectively. 25(OH)D3 was more clearly detected in the plasma sample as the DEAPTAD derivative than the DAPTAD derivative owing to the lower background noise. DEAPTAD derivatization was also useful for the separation of 25(OH)D3 from a potent interfering metabolite, 3‐epi‐25‐hydroxyvitamin D3. By using DEAPTAD, a trace amount of 25(OH)D3 in dried blood spots was reproducibly determined without interference from coexisting compounds. Thus, DEAPTAD was proved useful in the measurement of 25(OH)D3 in neonatal blood samples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
998.
Asymmetric Synthesis of an Amino Acid Derivative from Achiral Aroyl Acrylamide by Reversible Michael Addition and Preferential Crystallization 下载免费PDF全文
Yuki Kaji Naohiro Uemura Prof. Yoshio Kasashima Hiroki Ishikawa Prof. Yasushi Yoshida Prof. Takashi Mino Prof. Masami Sakamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16429-16432
Single‐handed α‐amino acid derivatives were generated from achiral precursors without an external chiral source. Conjugate addition of phenethylamine to an achiral aroyl acrylamide under homogeneous conditions gave the α‐amino amides in quantitative yields, which crystallized as a conglomerate of a P21 crystal system. Dynamic preferential crystallization or attrition‐enhanced deracemization resulted in the formation of enantiomorphic crystals of 99 % ee. 相似文献
999.
Hiroki Nakayama Shingo Harada Ayaka Kanda Irene Mei-Yi Kwok Tetsuhiro Nemoto 《Tetrahedron》2018,74(20):2435-2439
We previously developed a chemoselective asymmetric phenol dearomatization using a silver catalyst and benzoic acid as an additive to enhance the reaction efficiency. The mechanistic role of the additive, however, remained unclear. Herein we describe detailed studies to elucidate the additive effect, which revealed that benzoic acid plays two supporting roles in the silver-catalyzed reaction. First, it promotes protonation of a silver enolate intermediate to improve the chemical yield of a spirolactam. Second, it dissociates a homochiral dimer of silver phosphate to generate a monomeric species. 相似文献
1000.
Beom-Seok Ko Kimio Yoshimura Akihiro Hiroki Yasunari Maekawa 《Journal of polymer science. Part A, Polymer chemistry》2021,59(1):108-116
The radiation-induced graft polymerization (RGP) of styrene into poly(ethylene-co-tetrafluoroethylene) films was performed at various monomer concentrations and solvents at 60 °C. The grafted polystyrene (g-PS) was isolated using the swelling-induced detachment phenomenon, and the number-averaged molecular weight (Mn) and the number of g-PS (Np) were determined using gel permeation chromatography. The Mn increased consistently with an increase in the grafting time up to 2–3 hours, indicating very low termination rates, which was a result of the “gel effect”. This is the first direct evidence of the gradual Mn increase over time using RGP in thermally and chemically stable polymer films such as fluorinated polymers. When the Mn and Np were plotted as a function of the degree of grafting (DOG), sudden Np drops along with rapid Mn increases were observed in the DOG region of 80–90%, indicating negligible initiation and propagation; however, a recombination termination between two propagating g-PS radicals dominated the later part of the grafting process. Further increases in both Mn and Np were observed subsequently, implying that reinitiation and propagation events were triggered by morphological changes, as observed by small- and ultrasmall-angle X-ray scattering experiments, which liberated the dormant radicals from the lamellar crystals. 相似文献