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61.
Facile Synthesis of Dibenzopentalene Dianions and Their Application as New π‐Extended Ligands
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Takuya Kuwabara Dr. Kazuya Ishimura Prof. Dr. Takahiro Sasamori Prof. Dr. Norihiro Tokitoh Prof. Dr. Masaichi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7571-7575
Reduction of phenyl(silyl)ethynes with potassium followed by quenching with iodine gave dibenzopentalenes in moderate yields. The intermediates of the reactions, dipotassium dibenzopentalenides, were isolated. The first dibenzopentalene–transition‐metal complex was successfully synthesized. The ruthenium atoms are located above the six‐membered rings. However, X‐ray diffraction analysis and theoretical calculations revealed that the aromatic nature of the five‐membered rings was retained. The cyclic voltammetry of the Ru complex revealed two oxidation waves with relatively large separation. 相似文献
62.
An Isotope‐Coded Fluorogenic Cross‐Linker for High‐Performance Target Identification Based on Photoaffinity Labeling
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Dr. Takenori Tomohiro Shota Morimoto Toshiya Shima Dr. Junya Chiba Dr. Yasumaru Hatanaka 《Angewandte Chemie (International ed. in English)》2014,53(49):13502-13505
A photoaffinity labeling (PAL)‐based method for the rapid identification of target proteins is presented in which a high‐performance chemical tag, an isotope‐coded fluorescent tag (IsoFT), can be attached to the interacting site by irradiation. Labeled peptides can be easily distinguished among numerous proteolytic digests by sequential detection with highly sensitive fluorescence spectroscopy and mass spectrometry. Subsequent MS/MS analysis provides amino acid sequence information with a higher depth of coverage. The combination of PAL and heterogeneous target‐selecting techniques significantly reduces the amount of time and protein required for identification. An additional photocleavable moiety successfully accelerated proteomic analysis using cell lysate. This method is a widely applicable approach for the rapid and accurate identification of interacting proteins. 相似文献
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64.
Shuntaro Matsuta Noriaki Shima Hidenao Kakehashi Akari Ishikawa Ryutaro Asai Atsushi Nitta Misato Wada Shihoko Nakano Hiroe Kamata Yoshio Nishiyama Hirohisa Nagatani Hisanori Imura Munehiro Katagi 《Journal of mass spectrometry : JMS》2020,55(9)
Various cathinone‐derived designer drugs (CATs) have recently appeared on the drug market. This study examined the mechanism for the generation of dehydrated ions for CATs during electrospray ionization collision‐induced dissociation (ESI‐CID). The generation mechanism of dehydrated ions is dependent on the amine classification in the cathinone skeleton, which is used in the identification of CATs. The two hydrogen atoms eliminated during the dehydration of cathinone (primary amine) and methcathinone (secondary amine) were determined, and the reaction mechanism was elucidated through the deuterium labeling experiments. The hydrogen atom bonded to the amine nitrogen was eliminated with the proton added during ESI, in both of the tested compounds. This provided evidence that CATs with tertiary amine structures (such as dimethylcathinone and α‐pyrrolidinophenones [α‐PPs]) do not undergo dehydration. However, it was shown that the two major tertiary amine metabolites (1‐OH and 2″‐oxo) of CATs generate dehydrated ions in ESI‐CID. The dehydration mechanisms of the metabolites of α‐pyrrolidinobutiophenone (α‐PBP) belongs to α‐PPs were also investigated. Stable‐isotope labeling showed the dehydration of the 1‐OH metabolite following a simple mechanism where the hydroxy group was eliminated together with the proton added during ESI. In contrast, the dehydration mechanism of the 2″‐oxo metabolite involved hydrogen atoms in three or more locations along with the carbonyl group oxygen, indicating that dehydration occurred via multiple mechanisms likely including the rearrangement reaction of hydrogen atoms. These findings presented herein indicate that the dehydrated ions in ESI‐CID can be used for the structural identification of CATs. 相似文献
65.
Shahi Imam Reja Yuichiro Hori Takuya Kamikawa Kohei Yamasaki Miyako Nishiura Steven D. Bull Kazuya Kikuchi 《Chemical science》2022,13(5):1419
The ability to monitor proteolytic pathways that remove unwanted and damaged proteins from cells is essential for understanding the multiple processes used to maintain cellular homeostasis. In this study, we have developed a new protein-labeling probe that employs an ‘OFF–ON–OFF’ fluorescence switch to enable real-time imaging of the expression (fluorescence ON) and degradation (fluorescence OFF) of PYP-tagged protein constructs in living cells. Fluorescence switching is modulated by intramolecular contact quenching interactions in the unbound probe (fluorescence OFF) being disrupted upon binding to the PYP-tag protein, which turns fluorescence ON. Quenching is then restored when the PYP-tag–probe complex undergoes proteolytic degradation, which results in fluorescence being turned OFF. Optimization of probe structures and PYP-tag mutants has enabled this fast reacting ‘OFF–ON–OFF’ probe to be used to fluorescently image the expression and degradation of short-lived proteins.An “OFF–ON–OFF” fluorescence probe for real-time imaging of the expression (fluorescence ‘OFF’) and degradation (fluorescence ‘ON’) of short lived PYP-tag proteins in cellular systems. 相似文献
66.
Kentaro Yonesato Hiroyasu Ito Daisuke Yokogawa Kazuya Yamaguchi Kosuke Suzuki 《Angewandte Chemie (International ed. in English)》2020,59(38):16361-16365
Small Agn nanoclusters (n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face‐centered‐cubic‐type small {Ag7}5+ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si3W27O96]18?. The cluster showed unique {Ag7}5+‐to‐POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag7}5+ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O2, water, and solvents. 相似文献
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68.
Keika Hattori Kazuya Yamaguchi Junichiro Yamaguchi Kenichiro Itami 《Tetrahedron》2012,68(37):7605-7612
The palladium- and copper-catalyzed C–H arylation reactions of 1H- and 2H-indazoles with haloarenes are described. A PdCl2/phen/Ag2CO3/K3PO4 catalytic system is effective for the C–H arylation of 1H- and 2H-indazoles with haloarenes, whereas a less expensive CuI/phen/LiOt-Bu catalytic system is applicable to the C–H coupling of substituted 2H-indazoles and iodoarenes. The utility of newly developed catalyst was demonstrated in the rapid synthesis of YC-1 (an antitumor agent) and YD-3 (platelet anti-aggregating agent). These new reactions represent important direct functionalization tools of indazoles, well-known bioisosteres of pharmaceutically important indole core. 相似文献
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70.
Feroza Begum Yoshinori Namihira S. M. Abdur Razzak Shubi F. Kaijage Nguyen H. Hai Kazuya Miyagi Hiroki Higa Nianyu Zou 《Optical Review》2009,16(2):54-58
This research presents a simple index-guiding square photonic crystal fibers (SPCFs) that has a silica core surrounded by
air hole with two different diameters. It is demonstrated that the designed two-different-size hole-arrayed index-guiding
SPCFs has a ultra-flattened chromatic dispersion of 0 ± 0.9 ps/(nm·km) in a wavelength range of 1.34 to 1.61 μm and low confinement
loss of less than 10−7 dB/m in a wavelength range of 1.2 to 1.7 μm. It has also been shown that the proposed SPCFs show reasonable dispersion tolerance. 相似文献