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961.
Yukiya Kitayama Yasumichi Yazaki Junya Emoto Eiji Yuba Atsushi Harada 《Molecules (Basel, Switzerland)》2022,27(18)
A new programed upper critical solution temperature-type thermoresponsive polymer was developed using water-soluble anionic polymer conjugates derived from polyallylamine and phthalic acid with cleavage-induced phase transition property. Intrinsic charge inversion from anion to cation of the polymer side chain is induced through a side chain cleavage reaction in acidic aqueous media. With the progress of side chain cleavage under fixed external conditions, the polymer conjugates express a thermoresponsive property, followed by shifting a phase boundary due to the change in polymer composition. When the phase transition boundary eventually reached the examined temperature, phase transition occurs under fixed external conditions. Such new insight obtained in this study opens up the new concept of time-programed stimuli-responsive polymer possessing a cleavage-induced phase transition. 相似文献
962.
Kenichi Kato Shunsuke Ohtani Masayuki Gon Kazuo Tanaka Tomoki Ogoshi 《Chemical science》2022,13(44):13147
Spatial arrangement of multiple planar chromophores is an emerging strategy for molecule-based chiroptical materials via easy and systematic synthesis. We attached five pyrene planes to a chiral macrocycle, pillar[5]arene, producing a set of chiroptical molecules in which pyrene-derived absorption and emission were endowed with dissymmetry by effective transfer of chiral information. The chiroptical response was dependent on linker structures and substituted patterns because of variable interactions between pyrene units. One of these hybrids showed larger dissymmetry factor and response wavelength (glum = 7.0 × 10−3 at ca. 547 nm) than reported pillar[5]arene-based molecules using the pillar[5]arene cores as parts of photo-responsive π-conjugated units.Chirality of a C5-symmetric pillar[5]arene was effectively transmitted to pyrene arrays in hybrid molecules. The pyrenes showed achiral monomer fluorescence and circularly polarized excimer emission. 相似文献
963.
Dr. Eunji Lee Hyunsoo Ryu Huiyeong Ju Seulgi Kim Dr. Ji-Eun Lee Prof. Jong Hwa Jung Prof. Shunsuke Kuwahara Prof. Mari Ikeda Prof. Yoichi Habata Prof. Shim Sung Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(4):949-953
Some biological receptors change their shapes and rigidity by metalation to recognize substrates precisely via adaptive guest binding process. Herein we present a semi-flexible tricyclic host molecule whose conformation is rigidified by dimetalation to uptake organic guests selectively. Considering two metal binding sites and an empty space between them, pillar[5]-bis-thiacrown (L) was synthesized. The tricyclic host L forms a disilver(I) complex [Ag2L(NO3)2], with an Ag⋅⋅⋅Ag separation of 9.976 Å. Binding studies based on 1H NMR including 2D NOESY and DOSY experiments towards α,ω-dicyanoalkanes [CN(CH2)nCN, n=2–6, shortly C2–C6] demonstrated that the dimetalated L, Ag2L preferentially recognizes C2 over other guests than that of free L. Furthermore, the dimetalated the host only uptakes C2 in the presence of other guests. Crystal structures support the idea that the space between two silver(I) centers plays a decisive role on the selective guest binding forming an Ag-C2-Ag@L arrangement via the length-selective recognition. This work demonstrates the chemical example of the adaptive guest binding and presents a new perspective on the metallosupramolecules of pillararenes. 相似文献
964.
Takahiro Tsutsui Shunsuke Kusaba Dr. Masahiro Yamashina Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(17):4320-4324
Host functions of polyaromatic nanocavities were revealed by using an M2L4 molecular cage and capsule. On the basis of the previously reported M2L4 capsule with a closed polyaromatic cavity, a new M2L4 cage (as a mixture of the isomers) was prepared by the quantitative assembly of two metal ions and four desymmetrized bispyridine ligands with a single polyaromatic panel. The obtained, open nanocavity of the cage exhibited enhanced binding abilities toward large dyes and pigments in water. For example, two molecules of coumarin dyes were bound in the nanocavity and showed strong whitish emission (up to ΦF=34 %). Furthermore, metallopigments, the sizes of which are larger than the inner cavities of the cage and capsule, were bound only in the open polyaromatic nanocavity of the cage to give water-soluble 1:1 host–guest complexes. 相似文献
965.
Prof. Tsutomu Yokozawa Natsumi Harada Hajime Sugita Prof. Yoshihiro Ohta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10059-10062
Suzuki–Miyaura coupling reaction of BrC6H4-X-C6H4Br 1 (X=CH2, CO, N-Bu, O, S, SO, and SO2) with arylboronic acid 2 was investigated in the presence of tBu3PPd precatalyst and CsF/[18]crown-6 as a base to establish whether or not the Pd catalyst can undergo catalyst transfer on these functional groups. In the reaction of 1 (X=CH2, CO, N-Bu, O, and SO2) with 2 , aryl-disubstituted product 3 (Ar-C6H4-X-C6H4-Ar) was exclusively obtained, indicating that the Pd catalyst undergoes catalyst transfer on these functional groups. On the other hand, the reaction of 1 e (X=S) and 1 f (X=SO) with 2 afforded only aryl-monosubstituted product 4 (Ar-C6H4-X-C6H4-Br) and a mixture of 3 and 4 , respectively, indicating that S and SO interfere with intramolecular catalyst transfer. Furthermore, we found that Suzuki–Miyaura polycondensation of 1 (X=CH2, CO, N-Bu, O, and SO2) and phenylenediboronic acid 5 in the presence of tBu3PPd precatalyst afforded high-molecular-weight polymer even when excess 1 was used. The polymers obtained from 1 (X=CH2, N-Bu, and O) and 5 turned out to be cyclic. 相似文献
966.
Huie Zhu Shunsuke Yamamoto Jun Matsui Tokuji Miyashita 《Molecular Crystals and Liquid Crystals》2015,618(1):89-94
We prepared highly oriented ferroelectric poly(vinylidene fluoride) (PVDF) Langmuir–Blodgett (LB) nanofilms by an assistance of amphiphilic poly(N-dodecylacrylamide) (pDDA) nanosheets. In the nanofilms, semi-crystalline PVDF contains abundant polar β crystals, a parallel packing of PVDF all-trans molecules. Combing semi-conductive PEDOT:PSS and ferroelectric PVDF LB nanofilms, we fabricated a sandwiched capacitor (Al/PVDF LB nanofilm/PEDOT:PSS/Al). The capacitor shows asymmetric hysteresis curves and high remanent polarization values. 相似文献
967.
Yuta Watanabe Dr. Yohei Haketa Dr. Kazuto Nakamura Shunsuke Kaname Dr. Nobuhiro Yasuda Prof. Hiromitsu Maeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(30):6767-6772
The introduction of arylethynyl moieties at the pyrrole α- and β-positions of dipyrrolyldiketone BF2 complexes as anion-responsive π-electronic molecules was investigated. The arylethynyl-substituted derivatives formed a variety of anion complexes with planar [1+1]- and interlocked [2+1]-type structures in solution and in the solid state. The derivatives with long alkyl chains in the introduced arylethynyl groups also formed mesophases in the form of ion pairs of the anion complexes and a counter cation. The geometries of the constituent anion complexes affected the packing modes of the dimension-controlled assemblies. 相似文献
968.
969.
正Organic azides have shown versatile reactivity to induce various organic transformations for the synthesis of nitrogencontaining organic molecules such as 1,3-dipolar cycloadditions with unsaturated bonds, the Curtius rearrangement,and formation of nitrogen-centered radicals, most of which are driven by the entropic loss of molecular dinitrogen [1].Among organic azides, vinyl azides have shown unique re- 相似文献
970.
Prof. Dr. Tomoya Miura Yumi Ishihara Dr. Takayuki Nakamuro Shunsuke Moritani Prof. Dr. Yuuya Nagata Prof. Dr. Masahiro Murakami 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(10):e202103962
A rhodium(II)-catalyzed asymmetric cyclooligomerization of bifunctional monomers possessing triazolyl and vinyl groups at 2,3- and 3,4-positions on the thiophene ring is studied. Structurally interesting cyclic dimers in which thienylene and cyclopropylene units are alternately connected are obtained as the major components. The eight-membered rings in the center are non-planar and adopt a tub-shaped conformation. We also observe the phenomenon of racemization caused by a tub-to-tub ring-flipping, the activation energy of which is determined as 108 kJ mol−1 by electronic circular dichroism spectra measurement. 相似文献