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排序方式: 共有311条查询结果,搜索用时 15 毫秒
121.
Y Yang Y Xie Q Zhang K Nakatani H Tian W Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11685-11694
Three photochromic compounds-2-butyl-5,6-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]-1?H-benzo[de]isoquinoline-1,3(2?H)-dione (BTE-NA), 4,5-bis[5-(4-methoxyphenyl)-2-methylthiophen-3-yl]benzo[c][1,2,5]thiadiazole (BTA), and BTTA, which contain naphthalimide, benzothiadiazole, and benzobisthiadiazole as six-membered ethene bridges with different aromaticities-were systematically studied in solution, sol-gel, and single-crystal states. They exhibit typical photochromic performance with considerably high cyclization quantum yields. BTE-NA, BTA, and BTTA form a typical donor-π-acceptor (D-π-A) system with significant intramolecular charge transfer (ICT) between HOMO and LUMO upon excitation, thus realizing the fluorescence modulation by both photochromism and solvatochromism. The three ethene bridges with different degrees of aromaticity can provide a systematic comparison of the thermal stability evolution for their corresponding closed forms (c-BTE-NA, c-BTA, and c-BTTA). c-BTE-NA shows first-order decay in various solvents from cyclohexane to acetonitrile. c-BTA only shows first-order decay in polar solvents such as chloroform, whereas it is stable in nonpolar solvents like toluene. In contrast, the less aromatic property of BTTA gives rise to its unprecedented thermal stability in various solvents even at elevated temperatures in toluene (328?K). Moreover, the small energy barrier between the parallel and antiparallel conformers allows the full conversion from BTTA to c-BTTA. In well-ordered crystal states, all three compounds adopt a parallel conformation. Interestingly, BTTA forms a twin crystal of asymmetric nature with interactions between the electron-rich oxygen atom of the methoxy group and the carbon atom of the electron-deficient benzobisthiadiazole moiety. This work contributes to the understanding of aromaticity-controlled thermal stability of photochromic systems based on a six-membered ring as an ethene bridge, and a broadening of the novel building blocks for photochromic bisthienylethene systems. 相似文献
122.
Olivier Kahn Yu Pei Keitaro Nakatani Yves Journaux 《Molecular Crystals and Liquid Crystals》2013,570(1):481-493
One of the main challenges in the field of the molecular materials is the design of molecular-based ferromagnets. Our basic strategy along this line consists of assembling ferrimagnetic chains within the crystal lattice in a ferromagnetic fashion. This can be achieved owing to the (almost) limitless flexibility of the molecular chemistry. The chains may be either regular or alternating. Examples of both situations are presented. MnCu(pbaOH)(H2O)3 with pbaOH=2-hydroxy-1,3-propylenebis(oxamato) is a regular chain compound ordering ferromagnetically at TC=4.6 K, and MnCu(obbz).1H2O with obbz=oxamido-N,N′-bis(2-benzoato) is an alternating chain compound exhibiting a spontaneous magnetization below TC=14 K. To get information on the mechanism of the magnetic ordering, a broad spectrum of physical techniques is utilized, including magnetic susceptibility and magnetization measurements, EPR spectroscopy and heat capacity data. The perspectives in this new field are outlined. 相似文献
123.
Hanping He Dr. Masaki Hagihara Dr. Kazuhiko Nakatani Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10641-10648
A newly designed ligand, methylcarbamoylnaphthyridine dimer (MCND), was synthesized and characterized. Ligand binding to d(GAA)10 was investigated by UV thermal denaturation, circular dichroism spectroscopy, surface plasmon resonance, and cold‐spray‐ionization time‐of‐flight mass spectrometry. The results indicated that MCND bound to the d(GAA)n repeat to form a stable hairpin structure with a major binding stoichiometry of 3:1. The most likely binding site was identified as the G? G mismatch in the AGA/AGA triad. The polymerase stop assay showed that MCND binding to the d(GAA)n repeat effectively interfered with the extension of the primer at the first two GAA sites on the template with both prokaryotic Taq DNA polymerase and human DNA polymerase α. 相似文献
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Takeshi Nakatani Tomohiro Matsushita Yutaka Miyatake Tomohito Nohno Atsushi Kobayashi Keiki Fukumoto Shunsuke Okamoto Azusa Nakamoto Fumihiko Matsui Ken Hattori Masato Kotsugi Yuji Saitoh Shigemasa Suga Hiroshi Daimon 《Progress in Surface Science》2003,71(5-8):217-239
A stereograph of atomic arrangement was displayed directly on the screen of display-type spherical-mirror analyzer without any computer-aided conversion process for the first time. This stereoscopic photograph enables viewing three-dimensional atomic arrangement. This technique was realized taking advantage of the phenomenon of circular dichroism in photoelectron angular distribution. The azimuthal shifts of forward focusing peaks in a photoelectron angular distribution taken with left and right helicity light in a special arrangement are the same as the parallaxes in a stereo view of atoms. Hence a stereoscopic recognition of three-dimensional atomic arrangement is possible, when the left eye and the right eye respectively view the two images obtained by left and right helicity light simultaneously. 相似文献