排序方式: 共有73条查询结果,搜索用时 15 毫秒
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Ryo Kimura Dr. Hikaru Kuramochi Dr. Pengpeng Liu Takuya Yamakado Prof. Dr. Atsuhiro Osuka Prof. Dr. Tahei Tahara Prof. Dr. Shohei Saito 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(38):16572-16577
Flapping fluorophores (FLAP) with a flexible 8π ring are rapidly gaining attention as a versatile photofunctional system. Here we report a highly photostable “flapping peryleneimide” with an unprecedented fluorogenic mechanism based on a bent-to-planar conformational change in the S1 excited state. The S1 planarization induces an electronic configurational switch, almost quenching the inherent fluorescence (FL) of the peryleneimide moieties. However, the FL quantum yield is remarkably improved with a prolonged lifetime upon a slight environmental change. This fluorogenic function is realized by sensitive π-conjugation design, as a more π-expanded analogue does not show the planarization dynamics. With strong visible-light absorption, the FL lifetime response synchronized with the flexible flapping motion is useful for the latest optical techniques such as FL lifetime imaging microscopy (FLIM). 相似文献
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Dr. Mohammed Ahmed Dr. Ken-ichi Inoue Dr. Satoshi Nihonyanagi Prof. Dr. Tahei Tahara 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9585-9592
Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular-level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, that is, the tetraphenylborate-ion (TPB−)/water and tetraphenylarsonium-ion (TPA+)/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of the anionic TPB− interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen-bonded OH groups, which are hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen-bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region. 相似文献
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Daisuke Tomida Kiyoshi Kuroda Naruhiro Hoshino Kousuke Suzuki Yuji Kagamitani Toru Ishiguro Tsuguo Fukuda Chiaki Yokoyama 《Journal of Crystal Growth》2010,312(21):3161-3164
The solubility of GaN in supercritical ammonia with ammonium chloride as a mineralizer was measured with a weight-loss method. Temperature-, pressure-, and mineralizer concentration-dependence of the solubility of GaN were investigated. The solubility increased with increase in temperature, and its pressure dependence was very low. The solubility behavior was quite different from the case of using the mineralizer KNH2 as a basic mineralizer. 相似文献
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Removal of aqueous ammonium with magnesium phosphates obtained from the ammonium-elimination of magnesium ammonium phosphate 总被引:1,自引:0,他引:1
Sugiyama S Yokoyama M Ishizuka H Sotowa K Tomida T Shigemoto N 《Journal of colloid and interface science》2005,292(1):133-138
In order to recycle magnesium ammonium phosphate (MgNH4PO4.6H2O: MAP) obtained from MAP process, which is one of the attractive processes for removal of aqueous ammonium and phosphate from wastewater, ammonium elimination from MAP to magnesium phosphates and ammonium incorporation into the magnesium phosphates have been investigated in the present study. It is confirmed that magnesium hydrogen phosphate (MgHPO4) is favorably obtained from the ammonium elimination from MAP at temperatures greater than 353 K, although magnesium phosphate (Mg3(PO4)2) and magnesium pyrophosphate (Mg2P2O7) have been suggested as possible candidates. Based on the dissolution-precipitation mechanism for the removal of aqueous ammonium with magnesium phosphates, three magnesium phosphates were employed for the removal of aqueous ammonium. The order of the removal rate of the aqueous ammonium was MgHPO4>Mg3(PO4)2>Mg2P2O7, as expected from the solubility of those magnesium phosphates. The removability of the solid obtained from ammonium elimination of MAP is also confirmed. The present results show that MAP can be employed as an advanced material for the removal/recovery of ammonium, although it is generally accepted that an excess of MAP obtained from the wastewater treatment can be only used as a slow-acting fertilizer. 相似文献
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Masashi Hamaguchi Naoki Tomida Eiko Mochizuki Takumi Oshima 《Tetrahedron letters》2005,46(8):1259-1262
Reaction of azodicarboxylates with acyloxyketenes arising from dehydrochlorination of acyloxyphenylacetyl chlorides was carried out to give triacylamidine derivatives in good yields. The same triacylamidine derivatives were also obtained in good yields from the reaction with mesoionic 1,3-dioxolium-4-olates generated by Rh2(OAc)4-catalyzed decomposition of phenyldiazoacetic anhydride derivatives. Formation of the same compounds from different starting materials is explained by 1,3-dipolar addition between electron deficient NN bonds and mesoionic 1,3-dioxolium-4-olates, indicating fast equilibrium between acyloxyketenes and mesoionic 1,3-dioxolium-4-olates. 相似文献
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Katoh M Yoshikawa T Tomonari T Katayama K Tomida T 《Journal of colloid and interface science》2000,226(1):145-150
Adsorption characteristics of alkali metal ion-exchanged ZSM-5 zeolites, M-ZSM-5 (M=Li, Na, K, Rb, and Cs), for CO(2)/N(2) mixtures were investigated by a column method and IR study. It was shown that CO(2) was adsorbed from CO(2)/N(2) mixtures on M-ZSM-5 zeolites by two types of adsorbtion at temperatures below 333 K. One was a weak adsorption due to interaction with the wall of ZSM-5, and the other was a strong adsorption caused by interactions with the cation of ZSM-5. IR-spectra of gases adsorbed at various temperatures revealed that the CO(2) were strongly adsorbed on M-ZSM-5 in several ways, which seemed to be caused by different adsorption sites. At temperatures above 373 K, almost all CO(2) adsorbed were on cation sites, while N(2) coadsorbed with CO(2) was shown to interact with the wall of ZSM-5 under all experimental conditions. Copyright 2000 Academic Press. 相似文献
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Femtosecond fluorescence dynamics imaging microscopy was performed. Femtosecond fluorescence dynamics images were constructed based on the "mean" fluorescence decay or rise time constants that were evaluated by the time-resolved intensity sampling using a fluorescence up-conversion microscope. This dynamics imaging microscopy was carried out for the organic microcrystals alpha-perylene and tetracene-doped anthracene microcrystal, and ultrafast dynamics in the organic microcrystals were clearly imaged in the two-dimensional manner. For the alpha-perylene microcrystal, the obtained dynamics images showed that the crystal edges exhibited relatively shorter free exciton and the Y-state lifetimes compared to the crystal center, reflecting the higher concentration of defects. For the tetracene-doped anthracene microcrystal, the image was constructed based on the time constant of excitation energy transfer from anthracene to tetracene. By experiments changing the doping ratio of tetracene in anthracene, it was concluded that the inhomogeneity observed in the dynamics image arises from the difference in the local concentration of tetracene in the mixed crystal. 相似文献
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