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41.
Nadine Wellington Sabrina Macklai Prof. Philip Britz-McKibbin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(67):15277-15280
A zwitterionic heterocyclic boronic acid based on 4-isoquinolineboronic acid (IQBA) exhibits the highest reported binding affinity for sialic acid or N-acetylneuraminic acid (Neu5Ac, K=5390±190 m −1) through the formation of a cyclic boronate ester complex under acidic conditions (pH 3). This anomalous pH-dependent binding enhancement does not occur with common neutral saccharides (e.g., glucose, fructose, sorbitiol), because it is mediated via selective complexation to a α-hydroxycarboxylate moiety forming a stable ion pair and ternary complex with Neu5Ac in phosphate buffer. IQBA expands biorecognition beyond classical vicinal diols under neutral or alkaline buffer conditions, which enables the direct analysis of Neu5Ac by native fluorescence with sub-micromolar detection limits. 相似文献
42.
Jianlong Ma Chaoxian Yan Yijing Li Huixiao Duo Qiang Li Xiaofeng Lu Prof. Yong Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7168-7176
One of the most important endogenous reactive oxygen species, hypochlorous acid (HClO), is involved in numerous pathological and physiological processes. Herein, a near-infrared fluorescence probe (CyHR) was designed and synthesized for ultrafast (within 0.2 s), sensitive (limit of detection=39.44 nm ), and selective response to HClO. The reaction mechanism was systematically analyzed by MS, 1H NMR spectroscopy, HPLC-MS techniques, and theoretical calculations. The results indicated that HClO can be recognized by CyHR, which is based on chlorine–oxygen (Cl−O) bond formation. To the best of our knowledge, this study is the first to find Cl−O bonds among organic aromatic compounds, given that Cl−O bonds are common among inorganics. Through biological experiments, CyHR was successfully applied to image exogenous and endogenous HClO in macrophage cells (RAW 264.7). Thus, CyHR is a promising tool for HClO-related physiological and pathological studies and may provide a means for designing HClO-specific fluorescence probes. 相似文献
43.
Yun Bai Huaiyu Wang Jianghua He Yuetao Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11710-11716
An immortal N-(diphenylphosphanyl)-1,3-diisopropyl-4,5-dimethyl-1,3-dihydro-2H-imidazol-2-imine/diisobutyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum (P(NIiPr)Ph2/(BHT)AliBu2)-based frustrated Lewis pair (FLP) polymerization strategy is presented for rapid and scalable synthesis of the sequence-controlled multiblock copolymers at room temperature. Without addition of extra initiator or catalyst and complex synthetic procedure, this method enabled a tripentacontablock copolymer (n=53, k=4, dpn=50) to be achieved with the highest reported block number (n=53) and molecular weight (Mn=310 kg mol−1) within 30 min. More importantly, this FLP polymerization strategy provided access to the multiblock copolymers with tailored properties by precisely adjusting the monomer sequence and block numbers. 相似文献
44.
Recyclable and reusable Pd(OAc)2/PPh3/PEG‐2000 system for homocoupling reaction of arylboronic acids under air without base 下载免费PDF全文
A stable and efficient Pd(OAc)2/PPh3/PEG‐2000 catalytic system for homocoupling of arylboronic acids has been developed. In the presence of Pd(OAc)2 and PPh3, the homocoupling reaction of arylboronic acids was carried out smoothly in PEG‐2000 at 70 °C under air without base to afford a variety of symmetric biaryls in good to excellent yields. The isolation of the products was readily performed by extraction with diethyl ether, and the Pd(OAc)2/PPh3/PEG‐2000 system could be easily recycled and reused six times without significant loss of catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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46.
Simultaneous quantification of leukotrienes and hydroxyeicosatetraenoic acids in cell culture medium using liquid chromatography/tandem mass spectrometry 下载免费PDF全文
Leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are important bioactive lipid mediators that participate in various pathophysiological processes. To advance understanding of the mechanisms that regulate these mediators in physiological and pathological processes, an analytical method using liquid chromatography/tandem mass spectrometry for the simultaneous quantification of LTB4, LTC4, LTD4, LTE4, 5‐HETE, 8‐HETE, 12‐HETE and 15‐HETE in cell culture media was developed. A Supel?‐Select HLB solid‐phase extraction cartridge was used for sample preparation. The compounds were separated on a C18 column using gradient elution with acetonitrile–water–formic acid (20:80:0.1, v/v/v) and acetonitrile–formic acid (100:0.1, v/v). The calibration curves of LTB4, LTD4, LTE4 and HETEs were linear in the range of 0.025–10 ng/mL, and the calibration curve of LTC4 was linear in the range of 0.25–10 ng/mL. Validation assessment showed that the method was highly reliable with good accuracy and precision. The stability of LTs and HETEs was also investigated. Using the developed method, we measured LTs and HETEs in the culture supernatant of the human mast cell line HMC‐1. The present method could facilitate investigations of the mechanisms that regulate the production, release and signaling of LTs and HETEs. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
47.
48.
Identification of metabolites of rupestonic acid in rat urine by liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry 下载免费PDF全文
Dongyu Gu Yi Yang Qibin Chen Madina Habasi Jiangyu Zhao Haji Akber Aisa 《Biomedical chromatography : BMC》2015,29(4):595-603
Rupestonic acid, a potential anti‐influenza agent, is an important and characteristic compound in Artemisia rupestris L., a well‐known traditional Uighur medicine for the treatment of colds. In the present study, high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry was used to detect and identify the metabolites in rat urine after oral administration of rupestonic acid. A total of 10 metabolites were identified or partially characterized. The structure elucidations of the metabolites were performed by comparing the changes in accurate molecular masses and fragment ions with those of the parent compound. The results showed that the main metabolites of rupestonic acid in rat urine were formed by oxidation, hydrogenation and glucuronidation. A metabolism pathway was proposed for the first time based on the characterized structures. This metabolism study can provide essential information for drug discovery, design and clinical application of rupestonic acid. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
49.
Highly dispersed palladium nanoclusters incorporated in amino‐functionalized silica spheres for the selective hydrogenation of succinic acid to γ‐butyrolactone 下载免费PDF全文
Highly dispersed palladium nanoclusters incorporated on amino‐functionalized silica sphere surfaces (Pd/SiO2‐NH2) were fabricated by a simple one‐pot synthesis utilizing 3‐(2‐aminoethylamino)propyltrimethoxysilane (AAPTS) as coordinating agent. Uniform palladium nanoclusters with an average size of 1.1 nm can be obtained during the co‐condensation of tetraethyl orthosilicate and AAPTS owing to the strong interaction between palladium species and amino groups in AAPTS. The palladium particle size can be controlled by addition of AAPTS and plays a significant role in the catalytic performance. The Pd/SiO2‐NH2 catalyst exhibits high catalytic activity for succinic acid hydrogenation with 100% conversion and 94% selectivity towards γ‐butyrolactone using 1,4‐dioxane as solvent at 240°C and 60 bar for 4 h. Moreover, the Pd/SiO2‐NH2 catalyst is robust and readily reusable without loss of its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
50.
Unprecedented Oxidative Addition and Metal‐Only Lewis Pair Chemistry of Antimony Trihalides 下载免费PDF全文
Prof. Dr. Holger Braunschweig Dr. Rian D. Dewhurst Florian Hupp Dr. Justin Wolf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1860-1862
Reaction of the zero‐valent platinum complex [Pt(PCy3)2] with SbF3 generates the cationic diplatinum stibenium complex [{(Cy3P)2Pt}2(μ‐SbF2)]+, the first unsupported metal‐only Lewis pair containing an antimony‐centered Lewis acid. In contrast, SbCl3 undergoes oxidative addition to [Pt(PCy3)2], resulting in the dihalostibanyl complex trans‐[PtCl(SbCl2)(PCy3)2], the first example of oxidative addition of an antimony–halide bond to a transition metal. 相似文献