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71.
Mio Matsumura Yuki Matsuhashi Masato Kawakubo Tadashi Hyodo Yuki Murata Masatoshi Kawahata Kentaro Yamaguchi Shuji Yasuike 《Molecules (Basel, Switzerland)》2021,26(1)
The expectation that antimony (Sb) compounds should display phosphorescence emissions based on the “heavy element effect” prompted our interest in the introduction of antimony to a biaryl as the bridging atom in a fused heterole system. Herein, the synthesis, molecular structures, and optical properties of novel benzene-fused heteroacenes containing antimony or arsenic atoms are described. The stiboles and arsole were prepared by the condensation of dibromo(phenyl)stibane or dichloro(phenyl)arsine with dilithium intermediates derived from the corresponding dibromo compounds. Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystal analysis revealed that the linear pentacyclic stibole was highly symmetric in both the solution and crystal states. In contrast, the curved pentacyclic stibole adopted a helical structure in solution, and surprisingly, only M helical molecules were crystallized from the racemate. All synthesized compounds produced very weak or no emissions at room temperature or in the solid state. In contrast, the linear penta- and tetracyclic stiboles exhibited clear phosphorescence emissions in the CHCl3 frozen matrix at 77 K under aerobic conditions. 相似文献
72.
Yuki Kitamura Yuki Murata Mizuki Iwai Mio Matsumura Shuji Yasuike 《Molecules (Basel, Switzerland)》2021,26(1)
Pd-catalyzed regioselective C–H arylation is a useful tool for the chemical modification of aromatic heterocycles and 2-arylbenzofuran derivatives are of interest as biologically active substances. Herein, the reaction of triarylantimony difluorides with benzofurans under aerobic conditions in 1,2-DCE, using 5 mol% Pd (OAc)2 and 2 eq. of CuCl2 at 80 °C, produced a variety of 2-arylbenzofurans in moderate-to-high yields. The reaction is sensitive to the electronic nature of the substituents on the benzene ring of the triarylantimony difluorides: an electron-donating group showed higher reactivity than an electron-withdrawing group. Single crystal X-ray analysis of tri(p-methylphenyl) antimony difluoride revealed that the central antimony atom exhibits trigonal bipyramidal geometry. 相似文献
73.
Hoover S Nam J Gorham PW Grashorn E Allison P Barwick SW Beatty JJ Belov K Besson DZ Binns WR Chen C Chen P Clem JM Connolly A Dowkontt PF DuVernois MA Field RC Goldstein D Vieregg AG Hast C Israel MH Javaid A Kowalski J Learned JG Liewer KM Link JT Lusczek E Matsuno S Mercurio BC Miki C Miočinović P Naudet CJ Ng J Nichol RJ Palladino K Reil K Romero-Wolf A Rosen M Ruckman L Saltzberg D Seckel D Varner GS Walz D Wu F 《Physical review letters》2010,105(15):151101
We report the observation of 16 cosmic ray events with a mean energy of 1.5 × 101? eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2° for the event arrival directions. 相似文献
74.
Takeshi Sakai Takehiko Yagi Ryosuke Takeda Toshiki Hamatani Yuki Nakamoto Hirokazu Kadobayashi 《高压研究》2020,40(1):12-21
ABSTRACTBoth micro-paired and conical support type double-stage diamond anvil cells (ds-DAC) were tested using a newly synthesized ultra-fine nano-polycrystalline diamond (NPD). Well-focused X-ray sub-micron beam and the conically supported 2nd stage anvils (micro-anvils) with 10?μm culet enable us to obtain good quality X-ray diffraction peaks from the sample at around 400?GPa. The relationship between confining pressure and sample pressure depends heavily on the initial height (thickness) of micro-anvils, the difference of a few micrometers leads to a quite different compression path. The conical support type is a solution to retain both enough thickness and strength of micro-anvils at higher confining pressure conditions. All conical support ds-DAC experiments terminated by the failure of the 1st stage anvil instead of 2nd one. The combination of ultra-fine NPD 2nd stage anvil and NPD 1st stage anvil opens a new frontier for measurement of the X-ray absorption spectrum above 300?GPa. 相似文献
75.
Shuhei Furukawa Kenji Hirai Keiji Nakagawa Yohei Takashima Ryotaro Matsuda Takaaki Tsuruoka Mio Kondo Rie Haruki Daisuke Tanaka Hirotoshi Sakamoto Satoru Shimomura Osami Sakata Susumu Kitagawa 《Angewandte Chemie (International ed. in English)》2009,48(10):1697-1697
A porous copper coordination framework grew epitaxially as a single crystal on the surface of a single crystal of a porous zinc coordination framework, as described by S. Kitagawa and co‐workers in their Communication on page 1766 ff. The picture shows the structural relationship between the copper and zinc frameworks, which has been unveiled by synchrotron surface X‐ray diffraction measurements; in‐plane rotational epitaxial growth compensates for the different lattice constants of the two crystals.
76.
77.
Lee VY Fukawa T Nakamoto M Sekiguchi A Tumanskii BL Karni M Apeloig Y 《Journal of the American Chemical Society》2006,128(35):11643-11651
((t)Bu(2)MeSi)(2)Sn=Sn(SiMe(t)Bu(2))(2) 1, prepared by the reaction of (t)Bu(2)MeSiNa with SnCl(2)-diox in THF and isolated as dark-green crystals, represents the first example of acyclic distannene with a Sn=Sn double bond that is stable both in the crystalline form and in solution. This was proved by the crystal and NMR spectral data of 1. Distannene 1 has these peculiar structural features: a shortest among all acyclic distannenes Sn=Sn double bond of 2.6683(10) A, a nearly planar geometry around both Sn atoms, and a highly twisted Sn=Sn double bond. The reactions of 1 toward carbon tetrachloride and phenylacetylene also correspond to the reactivity anticipated for the Sn=Sn double bond. The one-electron reduction of 1 with potassium produced the distannene anion radical, the heavy analogue of alkene ion radicals, for which the particular crystal structure and low-temperature EPR behavior are also discussed. 相似文献
78.
Let G be a graph and let S?V(G). We say that S is dominating in G if each vertex of G is in S or adjacent to a vertex in S. We show that every triangulation on the torus and the Klein bottle with n vertices has a dominating set of cardinality at most $\frac{n}{3}Let G be a graph and let S?V(G). We say that S is dominating in G if each vertex of G is in S or adjacent to a vertex in S. We show that every triangulation on the torus and the Klein bottle with n vertices has a dominating set of cardinality at most $\frac{n}{3}$. Moreover, we show that the same conclusion holds for a triangulation on any non‐spherical surface with sufficiently large representativity. These results generalize that for plane triangulations proved by Matheson and Tarjan (European J Combin 17 (1996), 565–568), and solve a conjecture by Plummer (Private Communication). © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 17–30, 2010 相似文献
79.
Innocenzi P Kidchob T Bertolo JM Piccinini M Guidi MC Marcelli C 《The journal of physical chemistry. B》2006,110(22):10837-10841
Rapid scan time-resolved infrared spectroscopy has been used to investigate in situ the kinetics of the chemical processes involved in the formation of self-assembled mesostructured films. The experiments have been done in transmission mode on films cast on a diamond disk using an infrared microscope. Two specific materials have been studied: silica and titania mesoporous films templated by a triblock copolymer surfactant (Pluronic F-127). The time dependence of solvent evaporation and condensation of the chemical species have been clearly observed. Different stages in the film formation have been identified, which support well the general theory of self-assembly. The in situ FTIR spectroscopy using time-resolved rapid scan has proven to be a very effective tool for in situ analysis of film formation from a liquid phase. 相似文献
80.
Mio Koyama Akito Shimomura Katsuhiko Miyamoto Takashige Omatsu 《Applied physics. B, Lasers and optics》2014,116(2):249-254
The frequency-doubling of a picosecond vortex fiber laser, formed of a 1-μm picosecond master laser and a large-mode-area fiber amplifier by using a nonlinear LiB3O5, crystal, was performed. A maximum second-harmonic power of 7.7 W was achieved, corresponding to a conversion efficiency of 31 %. The second harmonic had an annular spatial form owing to a phase singularity with a doubled topological charge, and its wavefront helicity was selectively controlled by tuning the stress applied to the fiber amplifier. 相似文献