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641.
642.
Hye Jin Choi Taek Soon Lee Myunghyun Paik Suh 《Angewandte Chemie (International ed. in English)》1999,38(10):1405-1408
A three-dimensional network with one-dimensional channels (see picture) has been self-assembled from the nickel(II ) complex of cyclam and 1,3,5-benzenetricarboxylate in water through hydrogen-bond formation. The channels have an appropriate diameter (10.3 Å) to include D -glucose with a formation constant of Kf=(1.38±0.01)×104 M −1. Under similar conditions maltose is not included. 相似文献
643.
644.
Jungahn Kim Seo Young Jeong Kwang Ung Kim Young Hye Ahn Roderic P. Quirk 《Journal of polymer science. Part A, Polymer chemistry》1996,34(16):3277-3288
Studies on the mechanism for the formation of the stable dispersion polystyrene prepared by anionic dispersion polymerization of styrene in n-hexane using poly(t-butylstyrene) as the stabilizing moiety in steric stabilizer have been performed by a combination of size exclusion chromatographic (SEC) and transmission electron microscopic (TEM) analyses. When the molecular weight of poly(t-butylstyrene) as the stabilizing moiety exceeded 1.76 X 104 g/mol, the formed polymer particles successfully retained a steric stability. Block copolymerization of t-butylstyrene and styrene in n-hexane has also provided the dispersion polymer particles with a relatively narrow size distribution. The stable dispersion polystyrenes have been produced in n-hexane by polymerization of styrene using the mixture of sec-butyllithium and poly(t-butylstyryl)lithium. The polymerization is called living dispersion polymerization (LDP), in which poly(t-butylstyrene-b-styrene) as the steric stabilizer and polystyrene can be formed simultaneously. The particle size was readily controlled by a combination of the concentration of monomer and the molar ratio of poly(t-butylstyryl)lithium to sec-butyllithium, for instance, [stabilizing moiety]/[RLi]. © 1996 John Wiley & Sons, Inc. 相似文献
645.
Hee Yang Lee Dr. Seungyeop Baek Minhae Cha Prof. Seung-Hoon Yang Illhwan Cho Heewon Shin Dr. Sejin Lee Dr. Hye Yun Kim Songmin Lee Dr. Jisu Shin Dr. Donghee Lee Kyeonghwan Kim InWook Park Soljee Yoon Dr. Jiyoon Kim Seong Jeong Park Dr. Seong Muk Kim Ko Eun Kim Hye Ju Kim Min-Seok Oh Dr. Gwan-Ho Lee Dr. Byung-Yong Yu Priyadharshini Kannan Dr. Keunwan Park Prof. YoungSoo Kim 《Angewandte Chemie (International ed. in English)》2023,62(7):e202210209
Amyloid-β (Aβ) in the form of neurotoxic aggregates is regarded as the main pathological initiator and key therapeutic target of Alzheimer's disease. However, anti-Aβ drug development has been impeded by the lack of a target needed for structure-based drug design and low permeability of the blood–brain barrier (BBB). An attractive therapeutic strategy is the development of amyloid-based anti-Aβ peptidomimetics that exploit the self-assembling nature of Aβ and penetrate the BBB. Herein, we designed a dimeric peptide drug candidate based on the N-terminal fragment of Aβ, DAB, found to cross the BBB and solubilize Aβ oligomers and fibrils. Administration of DAB reduced amyloid burden in 5XFAD mice, and downregulated neuroinflammation and prevented memory impairment in the Y-maze test. Peptide mapping assays and molecular docking studies were utilized to elucidate DAB-Aβ interaction. To further understand the active regions of DAB, we assessed the dissociative activity of DAB with sequence modifications. 相似文献
646.
647.
Dr. Hye Won Moon Dr. Feng Wang Dr. Kalishankar Bhattacharyya Dr. Oriol Planas Dr. Markus Leutzsch Dr. Nils Nöthling Dr. Alexander A. Auer Dr. Josep Cornella 《Angewandte Chemie (International ed. in English)》2023,62(49):e202313578
Organobismuth-catalyzed transfer hydrogenation has recently been disclosed as an example of low-valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide mechanistic insights into a Bi-catalyzed transfer hydrogenation of azoarenes using p-trifluoromethylphenol ( 4 ) and pinacolborane ( 5 ) as hydrogen sources. A kinetic analysis elucidated the rate orders in all components in the catalytic reaction and determined that 1 a (2,6-bis[N-(tert-butyl)iminomethyl]phenylbismuth) is the resting state. In the transfer hydrogenation of azobenzene using 1 a and 4 , an equilibrium between 1 a and 1 a ⋅ [OAr]2 (Ar=p-CF3−C6H4) is observed, and its thermodynamic parameters are established through variable-temperature NMR studies. Additionally, pKa-gated reactivity is observed, validating the proton-coupled nature of the transformation. The ensuing 1 a ⋅ [OAr]2 is crystallographically characterized, and shown to be rapidly reduced to 1 a in the presence of 5 . DFT calculations indicate a rate-limiting transition state in which the initial N−H bond is formed via concerted proton transfer upon nucleophilic addition of 1 a to a hydrogen-bonded adduct of azobenzene and 4 . These studies guided the discovery of a second-generation Bi catalyst, the rate-limiting transition state of which is lower in energy, leading to catalytic transfer hydrogenation at lower catalyst loadings and at cryogenic temperature. 相似文献