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151.
Soichiro Nakatsuka Yusuke Watanabe Yoshinobu Kamakura Satoshi Horike Daisuke Tanaka Takuji Hatakeyama 《Angewandte Chemie (International ed. in English)》2020,59(4):1435-1439
A triphosphaazatriangulene (H3L) was synthesized through an intramolecular triple phospha‐Friedel–Crafts reaction. The H3L triangulene contains three phosphinate groups and an extended π‐conjugated framework, which enables the stimuli‐responsive reversible transformation of [Cu(HL)(DMSO)?(MeOH)]n, a 3D‐MOF that exhibits reversible sorption characteristics, into (H3L?0.5 [Cu2(OH)4?6 H2O] ?4 H2O), a 1D‐columnar assembled proton‐conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10?3 S cm?1 at 95 % relative humidity and 60 °C. 相似文献
152.
Yong‐Sheng Wei Liming Sun Miao Wang Jinhua Hong Lianli Zou Hongwen Liu Yu Wang Mei Zhang Zheng Liu Yinwei Li Satoshi Horike Kazu Suenaga Qiang Xu 《Angewandte Chemie (International ed. in English)》2020,59(37):16013-16022
Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal–organic framework encapsulating a trinuclear FeIII2FeII complex (denoted as Fe3) within the channels, a well‐defined nitrogen‐doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII/CoII) via synthesizing isostructural trinuclear‐complex precursors (Fe2Zn/Fe2Co), namely the “heteroatom modulator approach”, is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal–nitrogen moiety, clearly identified by direct transmission electron microscopy and X‐ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal–metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities. 相似文献
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154.
Dr. Naruyoshi Komiya Nao Itami Prof. Takeshi Naota 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9497-9505
Morphology control for intense solid‐state phosphorescence of non‐emissive, but potentially emissive crystals of platinum complexes and the mechanistic rationale are described. A series of trans‐bis(salicylaldiminato)platinum(II) complexes bearing linear alkyl chains ( 1 a : n=5; 1 b : n=8; 1 c : n=12; 1 d : n=14; 1 e : n=16; 1 f : n=18) was synthesized and the solid‐state emission properties were examined by using crystals/aggregates prepared under various precipitation conditions. Crystals of 1 e , prepared using “kinetic” conditions including rapid cooling, high concentrations, and poor solvents, emit intensive yellow phosphorescence (λmax=545 nm) under UV irradiation at 298 K with an absolute quantum efficiency of 0.36, whereas all the crystals of 1 a – 1 f prepared using “thermodynamic” conditions including slow cooling, low concentrations, and good solvents were either non‐ or less emissive with Φ298K values of 0.12 ( 1 a ), 0.11 ( 1 b ), 0.10 ( 1 c ), 0.07 ( 1 d ), 0.02 ( 1 e ), and 0.02 ( 1 f ) under the same measurement conditions. The amorphous solid 1 e , prepared by rapid cooling and freeze‐drying, was also non‐emissive (Φ298K=0.02, 0.02). Temperature‐dependent emission spectra showed that the kinetic crystals of 1 e exhibit high heat‐resistance towards emission decay with increasing temperature, whereas the amorphous solid 1 e is entirely heat‐quenchable. This is a rare example of the change from a non‐emissive crystal into a highly emissive crystal by morphology control through crystal engineering. Emission spectra and powder X‐ray diffraction (XRD) patterns of the emissive, kinetic crystals of 1 e are clearly distinct from those of the less emissive, thermodynamic crystals of 1 a – 1 f . Single‐crystal XRD unequivocally establishes that the thermodynamic crystals of 1 d have a multilayered lamellar structure supported by highly regulated, consecutive π‐stacking interactions between imine moieties, whereas the kinetic crystals of 1 e have a face‐to‐edge lamellar structure with less stacking. These results lead to the conclusion that 1) morphology control of long‐chained complexes exclusively generates a metastable herringbone‐based lamellar packing motif that exhibits intense emission and high heat‐resistance, while 2) a thermodynamically stable, highly regulated, consecutive stacking motif is unfavorable for solid‐state emission. 相似文献
155.
Nakamura R Kakeya K Furuta N Muta E Nishisaka H Mizutani T 《The Journal of organic chemistry》2011,76(15):6108-6115
Coupled oxidation of [tetraarylporphyrinato]iron(III) chloride carrying substituents in the ortho or para positions was performed by allowing the iron porphyrin to react with dioxygen, ascorbic acid, and pyridine to give biladienone as the major product and bilindione as a minor one. Efforts to find reaction conditions and workup procedures to obtain bilindione improved the yields of triarylbilindiones ranging between 2% and 19%. Electron-withdrawing substituents in the para position on the aryl groups increased the selectivity of bilindione relative to biladienone: the isolated yields of bilindione and biladienone were 2% and 85% (OMe), 6% and 44% (COOMe), and 7% and 28% (CN), respectively. Electronic effects of substituents affected both isolation procedures and the spectroscopic properties of bilindiones. Tri(4-methoxyphenyl)bilindione showed a red-shifted electronic absorption compared to unsubstituted and 4-methoxycarbonyl substituted analogues. This was ascribed to the destabilization of the HOMO-1 level by the methoxy groups. 相似文献
156.
Komatsu T Terada H Kobayashi N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(6):1849-1854
This report describes the synthesis and enzyme activities of multilayered protein nanotubes with an α-glucosidase (αGluD) interior surface. The nanotubes were prepared by using an alternating layer-by-layer (LbL) assembly of human serum albumin (HSA) and oppositely charged poly-L-arginine (PLA) into a track-etched polycarbonate (PC) membrane (pore size=400 nm) followed by addition of αGluD as the last layer of the wall. Subsequent dissolution of the PC template yielded (PLA/HSA)(2)PLA/αGluD nanotubes. SEM measurements revealed the formation of uniform hollow cylinders with (413±17) nm outer diameter and (52±3) nm wall thickness. In aqueous media, the nanotubes captured a fluorogenic glucopyranoside, 4-methyl-umbelliferyl-α-D-glucopyranoside (MUGlc), into their one-dimensional pore space and hydrolyzed the substrate efficiently to form α-D-glucose. We determined the enzyme parameters (Michaelis constant, K(M), and catalytic constant, k(cat), values) of the protein nanotubes. The several-micrometers-long cylinders were of sufficient length to be spun down by centrifugation at 4000 g, so the product could therefore be easily separated. Similar biocatalysts were prepared by complexation of biotinylated-αGluD into HSA-based nanotubes bearing a single avidin layer as an internal surface. The obtained hybrid nanotubes also exhibited the same enzyme activity for the MUGlc hydrolysis. 相似文献
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金属纳米结构的表面等离激元可以突破光学衍射极限,为光子器件的微型化和集成光学芯片的实现奠定基础.基于表面等离激元的各种基本光学元件已经研制出来.然而,由于金属结构的固有欧姆损耗以及向衬底的辐射损耗等,表面等离激元的传输能量损耗较大,极大地制约了其在纳米光子器件和回路中的应用.研究能量损耗的影响因素以及如何有效降低能量损耗对未来光子器件的实际应用具有重要意义.本文从纳米线表面等离激元的基本模式出发,介绍了它在不同条件下的场分布和传输特性,在此基础上着重讨论纳米线表面等离激元传输损耗的影响因素和测量方法以及目前常用的降低传输损耗的思路.最后给出总结以及如何进一步降低能量损耗方法的展望.表面等离激元能量损耗的相关研究对于纳米光子器件的设计和集成光子回路的构建有着重要作用. 相似文献
159.
Masafumi Ueda Mirai Kokubun Nao Yanagi Norifumi Yamamoto Yasuhiro Mazaki 《Molecules (Basel, Switzerland)》2022,27(21)
Janus-type triskelion-shaped fluorophores comprising coumarins bearing various electron-donating substituents (1aad, 1add, 1ccd, and 1cdd) were successfully synthesized via an intramolecular Ullmann coupling. Density functional theory (DFT) calculations indicated that all the compounds presented two different molecular surfaces, similar to Janus-type molecules. The absorption and fluorescence spectra of asymmetrical derivatives 1aad, 1add, 1ccd, and 1cdd exhibited a bathochromic shift due to their narrow highest occupied molecular orbital (HOMO) –lowest unoccupied molecular orbital (LUMO) gap. Natural transition orbital (NTO) analysis indicated that the excited state orbital overlaps differ among the C3 symmetrical and asymmetrical dyes. These triskelion-shaped fluorophores were found to form molecular nanoaggregates in THF/H2O mixtures and demonstrated aggregation-induced emission (AIE) enhancement characteristics as a result of restricting their molecular inversion. These results indicate that Janus-type AIE fluorophores are potentially applicable as solid-state fluorescent chiral materials, which can be optimized by controlling their molecular rearrangement in the solid state. 相似文献
160.
Nao Yao Legeng Yu Dr. Zhong-Heng Fu Dr. Xin Shen Dr. Ting-Zheng Hou Dr. Xinyan Liu Yu-Chen Gao Dr. Rui Zhang Dr. Chen-Zi Zhao Dr. Xiang Chen Prof. Qiang Zhang 《Angewandte Chemie (International ed. in English)》2023,62(41):e202305331
Viscosity is an extremely important property for ion transport and wettability of electrolytes. Easy access to viscosity values and a deep understanding of this property remain challenging yet critical to evaluating the electrolyte performance and tailoring electrolyte recipes with targeted properties. We proposed a screened overlapping method to efficiently compute the viscosity of lithium battery electrolytes by molecular dynamics simulations. The origin of electrolyte viscosity was further comprehensively probed. The viscosity of solvents exhibits a positive correlation with the binding energy between molecules, indicating viscosity is directly correlated to intermolecular interactions. Salts in electrolytes enlarge the viscosity significantly with increasing concentrations while diluents serve as the viscosity reducer, which is attributed to the varied binding strength from cation–anion and cation–solvent associations. This work develops an accurate and efficient method for computing the electrolyte viscosity and affords deep insight into viscosity at the molecular level, which exhibits the huge potential to accelerate advanced electrolyte design for next-generation rechargeable batteries. 相似文献