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排序方式: 共有3469条查询结果,搜索用时 15 毫秒
1.
Ryuto Yasui Dr. Daiki Shimizu Prof. Kenji Matsuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(27):e202104242
The single-molecular conductance between two π-conjugated wires with and without a radical substituent has been compared. Specifically, methyl- and iminonitroxide-substituted 4-(biphenyl-4-yl)pyridine wires bound onto a porphyrin template were subjected to scanning tunneling microscopy (STM) apparent-height measurement at the interface between highly oriented pyrolytic graphite (HOPG) and octan-1-oic acid. Statistical analysis of the STM images revealed that the radical-substituted wire has 3.2±1.7-fold higher conductance than the methyl-substituted reference. Although density functional theory (DFT) calculation suggests that only 17 % of the SOMO is distributed on the wire moiety, the effect was significant. This study presents the potential of radical substituents to achieve high conductivity in molecular wires. 相似文献
2.
Rational Molecular Design towards Vis/NIR Absorption and Fluorescence by using Pyrrolopyrrole aza‐BODIPY and its Highly Conjugated Structures for Organic Photovoltaics 下载免费PDF全文
Prof. Dr. Soji Shimizu Taku Iino Prof. Dr. Akinori Saeki Prof. Dr. Shu Seki Prof. Dr. Nagao Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2893-2904
Pyrrolopyrrole aza‐BODIPY (PPAB) developed in our recent study from diketopyrrolopyrrole by titanium tetrachloride‐mediated Schiff‐base formation reaction with heteroaromatic amines is a highly potential chromophore due to its intense absorption and fluorescence in the visible region and high fluorescence quantum yield, which is greater than 0.8. To control the absorption and fluorescence of PPAB, particularly in the near‐infrared (NIR) region, further molecular design was performed using DFT calculations. This results in the postulation that the HOMO–LUMO gap of PPAB is perturbed by the heteroaromatic moieties and the aryl‐substituents. Based on this molecular design, a series of new PPAB molecules was synthesized, in which the largest redshifts of the absorption and fluorescence maxima up to 803 and 850 nm, respectively, were achieved for a PPAB consisting of benzothiazole rings and terthienyl substituents. In contrast to the sharp absorption of PPAB, a PPAB dimer, which was prepared by a cross‐coupling reaction of PPAB monomers, exhibited panchromatic absorption across the UV/Vis/NIR regions. With this series of PPAB chromophores in hand, a potential application of PPAB as an optoelectronic material was investigated. After identifying a suitable PPAB molecule for application in organic photovoltaic cells based on evaluation using time‐resolved microwave conductivity measurements, a maximized power conversion efficiency of 1.27 % was achieved. 相似文献
3.
Daisuke Asai Tadashi Fukuda Kazunori Morokuma Daiki Funamoto Yuko Yamaguchi Takeshi Mori Yoshiki Katayama Keigo Shibayama Hideki Nakashima 《Macromolecular bioscience》2019,19(10)
Vaccines typically contain an antigen, delivery system (vehicle), and adjuvant, all of which contribute to inducing a potent immune response. Consequently, design of new vaccines is difficult, because the contributions and interactions of these components are difficult to distinguish. Here, it is aimed to develop an easy‐to‐use, non‐immunogenic, injectable depot system for sustained antigen release that will be suitable for assessing the efficacy of prolonged antigen exposure per se for inducing an immune response. This should mimic real‐life infections. Recombinant elastin‐like polypeptides with periodic cysteine residues (cELPs) are selected, which reportedly show little or no immunogenicity, as carriers and tetanus toxoid (Ttd) as an antigen. After subcutaneous injection of the mixture, cELP rapidly forms a disulfide cross‐linked hydrogel in situ, within which Ttd is physically incorporated, affording a biodegradable antigen depot. A series of Ttd‐containing hydrogels is examined. A single injection induces high levels of tetanus antibody with high avidity for at least 20 weeks in mice. The chain length of cELP proves critical, whereas differences in hydrophobicity has little effect, although hydrophilic cELPs are more rapidly biodegraded. This system's ability to distinguish the contribution of sustained antigen release to antibody induction should be helpful for rational design of next‐generation vaccines. 相似文献
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Prof. Dr. Masaki Shimizu Sho Nagano Takumi Kinoshita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5162-5167
Fluorescence–phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358–374 and 457–470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708–0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing. 相似文献
6.
Lars J. Wesenberg Erika Diehl Till J. B. Zähringer Carolin Dörr Dr. Dieter Schollmeyer Dr. Akihiro Shimizu Prof. Dr. Jun-ichi Yoshida Prof. Dr. Ute A. Hellmich Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17574-17580
The efficient production of many medicinally or synthetically important starting materials suffers from wasteful or toxic precursors for the synthesis. In particular, the aromatic non-protected primary amine function represents a versatile synthetic precursor, but its synthesis typically requires toxic oxidizing agents and transition metal catalysts. The twofold electrochemical amination of activated benzene derivatives via Zincke intermediates provides an alternative sustainable strategy for the formation of new C−N bonds of high synthetic value. As a proof of concept, we use our approach to generate a benzoxazinone scaffold that gained attention as a starting structure against castrate-resistant prostate cancer. Further improvement of the structure led to significantly increased cancer cell line toxicity. Thus, exploiting environmentally benign electrooxidation, we present a new versatile and powerful method based on direct C−H activation that is applicable for example the production of medicinally relevant compounds. 相似文献
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Dmitri V. Konarev Aleksey V. Kuzmin Salavat S. Khasanov Alexander F. Shestakov Akihiro Otsuka Hideki Yamochi Hiroshi Kitagawa Rimma N. Lyubovskaya 《化学:亚洲杂志》2020,15(17):2689-2695
Two salts of the aromatic hydrocarbon decacyclene, {cryptand[2.2.2](Cs+)} (decacyclene.?) ( 1 ) and {Bu3MeP+}(decacyclene.?) ( 2 ), were obtained. In both salts, decacyclene.? radical anions formed channels occupied by cations. However, corrugated hexagonal decacyclene.? layers could be outlined in the crystal structure of 1 with several side‐by‐side C???C approaches. The decacyclene.? radical anions showed strong distortion in both salts, deviating from the C3 symmetry owing to the repulsion of closely arranged hydrogen atoms and the Jahn‐Teller effect. Radical anions showed intense unusually low energy absorption in the IR‐range, with maxima at 4800 and 6000 cm?1. According to the carculations, these bands can originate from the SOMO‐LUMO+1 and SOMO‐LUMO+2 transitions, respectively. Radical anions exhibited a S=1/2 spin state, with an effective magnetic moment of 1.72 μB at 300 K. The decacyclene.? spin antiferromagnetically coupled with a Weiss temperature of ?11 K. Spin ordering was not observed down to 1.9 K owing to spin frustration in the hexagonal decacyclene.? layers. 相似文献
9.
Hirao Shigekazu Kakiuchi Hideki Akata Naofumi Tamari Toshiya Sugihara Shinji Shima Nagayoshi Yokoyama Sumi Tanaka Masahiro 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(7):3077-3083
Journal of Radioanalytical and Nuclear Chemistry - This paper discusses the spatiotemporal variation in atmospheric tritiated water (HTO) concentration near the Fukushima Daiichi Nuclear Power... 相似文献
10.
Noriko Shimizu Tomoji Ozeki Hideyasu Shikama Tsuneji Sano Masahiro Sadakane 《Journal of Cluster Science》2014,25(3):755-770
We found that three isomers of mono-Ru substituted Keggin-type germanotungstate with a dmso ligand, [GeW11O39RuII(dmso)]6?, could be formed by a reaction of α-Keggin-type mono-lacunary germanotungstate, [α-GeW11O39]8?, with Ru(dmso)4Cl2. The main isomer is an α-isomer, and the others are β2-isomer and β3-isomer, which were confirmed by 1H NMR, cyclic voltammetry, IR, and single crystal X-ray structure analysis. 相似文献