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141.
Dr. Yohei Adachi Taishi Nabeya Keigo Kawakami Kosuke Yamaji Prof. Dr. Frieder Jäkle Prof. Dr. Joji Ohshita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3306-3314
The introduction of unconventional elements into π-conjugated systems has been studied to manipulate the electronic states and properties of compounds. Herein, boron- and germanium-containing hybrid macrocycles, as a new class of element-hybrid conjugated systems, have been synthesized. The palladium-catalyzed Stille cross coupling of bis(bromothienyl)borane and bis(trimethylstannylthienyl)- or bis(trimethylstannylphenyl)-substituted dithienogermoles as the boron- and germanium-containing building blocks, respectively, produced a mixture of several macrocyclic compounds. Single-crystal X-ray analysis of the 2:2 coupling product revealed a planar structure with a cavity inside the macrocycle. The optical properties of the macrocyclic products indicated rather small electronic interactions between the building units. However, intramolecular photoenergy transfer from the dithienogermole unit to the boron unit was clearly observed with respect to the fluorescence spectra. 相似文献
142.
Iridium‐Catalyzed Reductive Carbon–Carbon Bond Cleavage Reaction on a Curved Pyridylcorannulene Skeleton 下载免费PDF全文
Dr. Shohei Tashiro Dr. Mihoko Yamada Prof. Dr. Mitsuhiko Shionoya 《Angewandte Chemie (International ed. in English)》2015,54(18):5351-5354
The cleavage of C? C bonds in π‐conjugated systems is an important method for controlling their shape and coplanarity. An efficient way for the cleavage of an aromatic C? C bond in a typical buckybowl corannulene skeleton is reported. The reaction of 2‐pyridylcorannulene with a catalytic amount of IrCl3?n H2O in ethylene glycol at 250 °C resulted in a structural transformation from the curved corannulene skeleton to a strain‐free flat benzo[ghi]fluoranthene skeleton through a site‐selective C? C cleavage reaction. This cleavage reaction was found to be driven by both the coordination of the 2‐pyridyl substituent to iridium and the relief of strain in the curved corannulene skeleton. This finding should facilitate the design of carbon nanomaterials based on C? C bond cleavage reactions. 相似文献
143.
A cholesterol-conjugated fluorescence Zn(2+) sensor based on the fluorescein platform was designed and synthesized. The cholesterol moiety is essential for localizing the Zn(2+) sensor to the cell membrane, allowing the sensor to probe changes in the Zn(2+) concentration in a localized area of the cell. 相似文献
144.
A phenanthroline-based macrocycle 1 has been newly developed which has two chemically equivalent metal chelating sites within the spatially restricted cavity for dinuclear metal arrangement. The macrocycle 1 reacts with Zn(CF(3)CO(2))(2) or ZnCl(2) to form homodinuclear Zn(II)-complexes. A single-crystal X-ray structural analysis of the resulting Zn(2)1(CF(3)CO(2))(4) determined the complex structure in which two Zn(II) ions are bound by two phenanthroline sites and two CF(3)CO(2)(-) ions bind to each Zn(II) ion in a tetrahedral geometry. Similarly, a homodinuclear Cu(I)-macrocycle was formed from 1 and Cu(CH(3)CN)(4)BF(4). Notably, from 1 and an equimolar mixture of Cu(CH(3)CN)(4)BF(4) and Zn(CF(3)CO(2))(2), a heterodinuclear Cu(I)-Zn(II)-macrocycle was exclusively formed in high yield (>90%) because of the relatively low stability of the dinuclear Cu(I)-macrocycle. A heterodinuclear Ag(I)-Zn(II)-macrocycle was similarly formed with fairly high selectivity from a mixture of Ag(I) and Zn(II) ions. Such selective heterodinuclear metal arrangement was not observed with other combinations of M-Zn(II) (M = Li(I), Mg(II), Pd(II), Hg(II), La(III), and Tb(III)). 相似文献
145.
Clever GH Kawamura W Tashiro S Shiro M Shionoya M 《Angewandte Chemie (International ed. in English)》2012,51(11):2606-2609
Neatly wrapped up: alternately stacked square-planar platinum(II) complexes inside a dinuclear coordination cage were prepared to give a discrete and soluble Pt(5) -array of the Magnus' salt type. Characterization of the complex in solution was complemented by an X-ray crystal structure of {[Pt(pyridine)(4)]? [PtCl(4)](2) @Cage}; this structure showed the linear, pentanuclear array within the cages and their circular packing into a hollow tubular superstructure. 相似文献
146.
Toshiyuki Iida Joji Ohshita Taisuke Uemura Hiroshi Fukuoka Nobuaki Ohta Kenji Komaguchi Yoshiteru Itagaki Masaru Shiotani Shoji Yamanaka Atsutaka Kunai 《Silicon Chemistry》2002,1(5-6):383-389
The spin states of a series of silicon- and carbon-bridged phenyl nitroxides were examined with respect to the temperature dependent ESR and SQUID measurements. Of those, a linear relationship between the ESR signal intensity and 1/T (T = absolute temperature) and an increase of χmolT along lowering T were observed for a compound having disilanylene-bridged m- and p-phenyl nitroxide units (Si2mp), indicating ferromagnetic spin-spin interaction in this molecule. In contrast to this, no clear intramolecular spin-spin interaction took place in the monosilanylene analogue (Si1mp). Mono- and disilanylene-bridged phenylnitroxides with p-, p- or m-, m-substitution (Si1pp,Si1mm, Si1pp, and Si2mm) exhibited the singlet ground state. The trisilanylene and siloxanylene bridges did not play an obvious role in the spin interaction, in either a ferro- or antiferromagnetic fashion, regardless of the substitution modes of the phenylenes. MO calculations on the model compounds provided a mechanistic interpretation for the high-spin interaction through the σ-π system. 相似文献
147.
Simultaneous Arrangement of up to Three Different Molecules on the Pore Surface of a Metal–Macrocycle Framework: Cooperation and Competition 下载免费PDF全文
Dr. Shohei Tashiro Tsutomu Umeki Dr. Ryou Kubota Prof. Dr. Mitsuhiko Shionoya 《Angewandte Chemie (International ed. in English)》2014,53(32):8310-8315
Porous crystals are excellent materials with potential spatial functions through molecular encapsulation within the pores. Co‐encapsulation of multiple different molecules further expands their usability and designability. Herein we report the simultaneous arrangement of up to three different guest molecules, TTF (tetrathiafulvalene), ferrocene, and fluorene, on the pore surfaces of a porous crystalline metal–macrocycle framework (MMF). The position and orientation of adsorbed molecules arranged in the pore were determined by single‐crystal X‐ray diffraction analysis. The anchoring effect of hydrogen bonds between the hydroxy groups of the guest molecules and inter‐guest cooperation and competition are significant factors in the adsorption behaviors of the guest molecules. This finding would serve as a design basis of multicomponent functionalized nanospaces for elaborate reactions that are realized in enzymes. 相似文献
148.
Kiyoshi Shibata Hiroshi Kimura Akira Tsuchida Tsuneo Okubo Shohei Sato Kohji Yoshinaga 《Colloid and polymer science》2006,284(4):372-379
Electro-optic responses of colloidal crystals consist of poly(maleic anhydride-co-styrene)-modified silica spheres (P(MA-ST)/SiO2) in acetonitrile and the crystals immobilized with a gelator, N-benzyloxycarbonyl-L-isoleucilaminooctadecane (Z-L-Ile-C-18), are studied by reflected-light intensity measurements and time-resolved reflection spectroscopy. Application of
an alternating electric field deforms P(MA-ST)/SiO2 crystal lattices reversibly. The response waveforms from the crystals are dependent on the frequency and strength of the
applied electric field; similar dependencies have been qualitatively observed for the colloidal crystals consisting of polystyrene
or silica spheres in aqueous media in our previous studies. Both gelated and ungelated P(MA-ST)/SiO2 crystals change the reflection intensity, however, the amplitude is larger for the latter. The small response for the gelated
P(MA-ST)/SiO2 crystals is attributed to the higher elastic modulus (G). The G value of the gelated P(MA-ST)/SiO2 crystals in acetonitrile is estimated from the change in the inter-sphere distance to be 8.0 Pa, which is about 2.3 and 2.4
times larger than that for ungelated P(MA-ST)/SiO2 crystals in acetonitrile and colloidal silica crystals in aqueous media, respectively. 相似文献
149.
Ohno H Hamaguchi H Ohata M Kosaka S Tanaka T 《Journal of the American Chemical Society》2004,126(28):8744-8754
We have developed a highly regio- and stereoselective synthesis of medium-sized heterocycles containing one or two heteroatoms via cyclization of bromoallenes bearing an oxygen, nitrogen, or carbon nucleophilic functionality in the presence of a palladium(0) catalyst and alcohol. In this reaction, bromoallenes act as an allyl dication equivalent, and the intramolecular nucleophilic attack takes place exclusively at the central carbon atom of the allene moiety. Interestingly, bromoallenes having a carbon nucleophile with a five-atom tether afford eight-membered rings with trans-configuration, while those having an oxygen or a nitrogen nucleophile give the corresponding cis-rings selectively. This is the first example that demonstrates the synthesis of medium-sized rings via cyclization of bromoallenes, and this reaction provides a very useful method for a catalytic synthesis of seven- and eight-membered heterocycles without using high dilution conditions. 相似文献
150.
Joji Ohshita 《Journal of organometallic chemistry》2006,691(9):1907-1911
Ring-opening halosilation of cyclic ethers with reagents of (Me2N)2SiMe2/4MeI (1a) and (Me2N)2SiMe2/4allylBr (1b) was studied. Tetrahydrofuran and cyclohexene oxide reacted with 1a and 1b to give ring-opened di(haloalkoxy)dimethylsilanes in good yield. With less strained tetrahydropyran, however, only reagent 1a gave the ring-opened product. Reactions of reagents 1a and 1b with propylene oxide also proceeded smoothly, although the regioselectivity was rather low. When similar reactions were carried out with (Me2N)2SiMe2/2MeI (2a) and (Me2N)2SiMe2/2allylBr (2b) in a ratio of cyclic ethers/2a or 2b = 1/1, the corresponding 1:1 adducts were obtained. 相似文献