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991.
Dr. Nicolai Wagner Milena Schuhmacher Annett Lohmann Dr. André Nadler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15483-15487
Photorelease of caged compounds is among the most powerful experimental approaches for studying cellular functions on fast timescales. However, its full potential has yet to be exploited, as the number of caged small molecules available for cell biological studies has been limited by synthetic challenges. Addressing this problem, a straightforward, one-step procedure for efficiently synthesizing caged compounds was developed. An in situ generated benzylic coumarin triflate reagent was used to specifically functionalize carboxylate and phosphate moieties in the presence of free hydroxy groups, generating various caged lipid metabolites, including a number of GPCR ligands. By combining the photo-caged ligands with the respective receptors, an easily implementable experimental platform for the optical control and analysis of GPCR-mediated signal transduction in living cells was developed. Ultimately, the described synthetic strategy allows rapid generation of photo-caged small molecules and thus greatly facilitates the analysis of their biological roles in live cell microscopy assays. 相似文献
992.
Tatsuya Sakakura Assoc. Prof. Naoya Murakami Dr. Yoshiyuki Takatsuji Masayuki Morimoto Prof. Tetsuya Haruyama 《Chemphyschem》2019,20(11):1467-1474
Electric-discharge nitrogen comprises three main types of excited nitrogen species-atomic nitrogen (Natom), excited nitrogen molecules (N2*), and nitrogen ions (N2+) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N-compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The Natom amount was analyzed quantitatively to clarify the contribution of Natom to the P/L reaction. We focused on the quantitative relationship between Natom and the produced N-compounds, and found that both N2* and N2+, which are active species other than Natom, contributed to P/L reaction. The production of N-compounds from N2* and N2+ was enhanced upon UV irradiation of the water phase, but the production of N-compounds from Natom did not increase by UV irradiation. These results revealed that the P/L reactions starting from Natom and those starting from N2* and N2+ follow different mechanisms. 相似文献
993.
994.
995.
Cover Picture: Densely Packed Hydrophobic Clustering: Encapsulated Valerates Form a High‐Temperature‐Stable {Mo132} Capsule System (Angew. Chem. Int. Ed. 23/2016) 下载免费PDF全文
996.
Realignment of Nanocrystal Aggregates into Single Crystals as a Result of Inherent Surface Stress 下载免费PDF全文
Zhaoming Liu Dr. Haihua Pan Genxing Zhu Yaling Li Dr. Jinhui Tao Biao Jin Prof. Ruikang Tang 《Angewandte Chemie (International ed. in English)》2016,55(41):12836-12840
Crystallization by particle attachment is widely observed in both natural and synthetic environments. Although this form of nonclassical crystallization is generally described by oriented attachment, random aggregation of building blocks to give single‐crystal products is also observed, but the mechanism of crystallographic realignment is unknown. We herein reveal that random attachment during aggregation‐based growth initially produces a nonoriented growth front. Subsequent evolution of the orientation is driven by the inherent surface stress applied by the disordered surface layer and results in single‐crystal formation by grain‐boundary migration. This mechanism is corroborated by measurements of orientation rate versus external stress, which demonstrated a predictive relationship between the two. These findings advance our understandings about aggregation‐based growth via nanocrystal blocks and suggest an approach to material synthesis that takes advantage of stress‐induced coalignment. 相似文献
997.
Dr. Yunxi Yao Prof. Konstantinos P. Giapis 《Angewandte Chemie (International ed. in English)》2016,55(38):11595-11599
Most Eley–Rideal abstraction reactions involve an energetic gas‐phase atom reacting directly with a surface adsorbate to form a molecular product. Molecular projectiles are generally less reactive, may dissociate upon collision with the surface, and thus more difficult to prove that they can participate intact in abstraction reactions. Here we provide experimental evidence for direct reactions occurring between molecular N2+ and O2+ projectiles and surface‐adsorbed D atoms in two steps: first, the two atoms of the diatomic molecule undergo consecutive collisions with a metal surface atom without bond rupture; and second, the rebounding molecule abstracts a surface D atom to form N2D and O2D intermediates, respectively, detected as ions. The kinematics of the collisional interaction confirms product formation by an Eley–Rideal reaction mechanism and accounts for inelastic energy losses commensurate with surface re‐ionization. Such energetic hydrogenation of dinitrogen may provide facile activation of its triple bond as a first step towards bond cleavage. 相似文献
998.
Lanthanide‐Catalyzed Reversible Alkynyl Exchange by Carbon–Carbon Single‐Bond Cleavage Assisted by a Secondary Amino Group 下载免费PDF全文
Yinlin Shao Fangjun Zhang Prof. Dr. Jie Zhang Prof. Dr. Xigeng Zhou 《Angewandte Chemie (International ed. in English)》2016,55(38):11485-11489
Lanthanide‐catalyzed alkynyl exchange through C?C single‐bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β‐alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo‐ and cross‐dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions. 相似文献
999.
A Programmable Signaling Molecular Recognition Nanocavity Prepared by Molecular Imprinting and Post‐Imprinting Modifications 下载免费PDF全文
Ryo Horikawa Dr. Hirobumi Sunayama Dr. Yukiya Kitayama Dr. Eri Takano Prof. Dr. Toshifumi Takeuchi 《Angewandte Chemie (International ed. in English)》2016,55(42):13023-13027
Inspired by biosystems, a process is proposed for preparing next‐generation artificial polymer receptors with molecular recognition abilities capable of programmable site‐directed modification following construction of nanocavities to provide multi‐functionality. The proposed strategy involves strictly regulated multi‐step chemical modifications: 1) fabrication of scaffolds by molecular imprinting for use as molecular recognition fields possessing reactive sites for further modifications at pre‐determined positions, and 2) conjugation of appropriate functional groups with the reactive sites by post‐imprinting modifications to develop programmed functionalizations designed prior to polymerization, allowing independent introduction of multiple functional groups. The proposed strategy holds promise as a reliable, affordable, and versatile approach, facilitating the emergence of polymer‐based artificial antibodies bearing desirable functions that are beyond those of natural antibodies. 相似文献
1000.
Dr. Jonathan Rittle Prof. Jonas C. Peters 《Angewandte Chemie (International ed. in English)》2016,55(40):12262-12265
Nitrogenase enzymes mediate the six‐electron reductive cleavage of cyanide to CH4 and NH3. Herein we demonstrate for the first time the liberation of CH4 and NH3 from a well‐defined iron cyanide coordination complex, [SiPiPr3]Fe(CN) (where [SiPiPr3] represents a tris(phosphine)silyl ligand), on exposure to proton and electron equivalents. [SiPiPr3]Fe(CN) additionally serves as a useful entry point to rare examples of terminally‐bound Fe(CNH) and Fe(CNH2) species that, in accord with preliminary mechanistic studies, are plausible intermediates of the cyanide reductive protonation to generate CH4 and NH3. Comparative studies with a related [SiPiPr3]Fe(CNMe2) complex suggests the possibility of multiple, competing mechanisms for cyanide activation and reduction. 相似文献