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61.
Jikun Li Xinxin Feng Wei Zhu Nikita Oskolkov Tianhui Zhou Boo Kyung Kim Noman Baig Prof. Michael T. McMahon Prof. Eric Oldfield 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):264-271
Diamagnetic chemical exchange saturation transfer (CEST) contrast agents offer an alternative to Gd3+‐based contrast agents for MRI. They are characterized by containing protons that can rapidly exchange with water and it is advantageous to have these protons resonate in a spectral window that is far removed from water. Herein, we report the first results of DFT calculations of the 1H nuclear magnetic shieldings in 41 CEST agents, finding that the experimental shifts can be well predicted (R2=0.882). We tested a subset of compounds with the best MRI properties for toxicity and for activity as uncouplers, then obtained mice kidney CEST MRI images for three of the most promising leads finding 16 (2,4‐dihydroxybenzoic acid) to be one of the most promising CEST MRI contrast agents to date. Overall, the results are of interest since they show that 1H NMR shifts for CEST agents—charged species—can be well predicted, and that several leads have low toxicity and yield good in vivo MR images. 相似文献
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Timur M. Bulatov Mikhail V. Pugachev Nikita V. Shtyrlin Yurii G. Shtyrlin 《Tetrahedron letters》2018,59(33):3220-3222
A new synthetic approach to 6-alkenyl-substituted pyridoxine derivatives was developed based on the Heck reaction. The reaction, which was catalyzed using a mixture of Pd(OAc)2, (o-Tol)3P and Bu3N as a base, led to seven new 6-alkenyl pyridoxine derivatives. When acrylic acid was used the products of decarboxylation and dimerization were formed. 相似文献
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A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones 下载免费PDF全文
Dr. Evgeniya A. Trifonova Nikita M. Ankudinov Dr. Andrey A. Mikhaylov Dr. Denis A. Chusov Dr. Yulia V. Nelyubina Prof. Dr. Dmitry S. Perekalin 《Angewandte Chemie (International ed. in English)》2018,57(26):7714-7718
The rapid development of enantioselective C?H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee). 相似文献
67.
M. Sc. Indrajit Paul M. Sc. Abir Goswami M. Sc. Nikita Mittal Prof. Dr. Michael Schmittel 《Angewandte Chemie (International ed. in English)》2018,57(1):354-358
Three supramolecular slider‐on‐deck systems DS1 – DS3 were obtained as two‐component aggregates from the sliders S1 – S3 and deck D with its three zinc porphyrin (ZnPor) binding sites. The binding of the two‐footed slider to the deck varies with the donor qualities of and the steric hindrance at the pyridine/pyrimidine (pyr) feet, and was effected by two Npyr→ZnPor interactions. Accordingly, the sliders move over the three zinc porphyrins in the deck at different speeds, namely with 32.2, 220, and 440 kHz at room temperature. The addition of N‐methylpyrrolidine as an organocatalyst to DS1 – DS3 generates catalytic three‐component machineries. By using a conjugate addition as a probe reaction, we observed a correlation between the operating speed of the slider‐on‐deck systems and the yields of the catalytic reaction. As the thermodynamic binding of the slider decreases, both the frequency of the sliding motion and the yield of the catalytic reaction increase. 相似文献
68.
Tatiana N. Drebushchak Nikita V. Chukanov Elena V. Boldyreva 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(12):o623-o625
The ɛ‐form of chlorpropamide [systematic name: 4‐chloro‐N‐(propylaminocarbonyl)benzenesulfonamide], C10H13ClN2O3S, has been obtained as single crystals from solution (and not as a polycrystalline sample by heating the α‐, γ‐ or δ‐forms). The results of anisotropic structure refinements for the ɛ‐ and δ‐forms are reported. The density of the δ‐polymorph is the highest, and that of the ɛ‐polymorph the lowest, among the five known chlorpropamide polymorphs. The main intermolecular hydrogen‐bonding pattern in polymorphs δ and ɛ is the same as in polymorphs α, β and γ, but the conformations differ. The densities of the polymorphs were found to depend on the molecular conformations. 相似文献
69.
Dr. Vasily G. Panferov Nikita A. Ivanov Dr. Tony Mazzulli Dr. Davor Brinc Dr. Vathany Kulasingam Prof. Sergey N. Krylov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215548
Lateral flow immunoassay (LFIA) is a rapid, simple, and inexpensive point-of-need method. A major limitation of LFIA is a high limit of detection (LOD), which impacts its diagnostic sensitivity. To overcome this limitation, we introduce a signal-enhancement procedure that is performed after completing LFIA and involves controllably moving biotin- and streptavidin-functionalized gold nanoparticles by electrophoresis. The nanoparticles link to immunocomplexes forming multilayer aggregates on the test strip, thus, enhancing the signal. Here, we demonstrate lowering the LOD of hepatitis B surface antigen from approximately 8 to 0.12 ng mL−1, making it clinically acceptable. Testing 118 clinical samples for hepatitis B showed that signal enhancement increased the diagnostic sensitivity of LFIA from 73 % to 98 % while not affecting its 95 % specificity. Electrophoresis-driven enhancement of LFIA is universal (antigen-independent), takes two minutes, and can be performed by an untrained person. 相似文献
70.
Elena V. Dorozhko Nikita A. Lunev Elena I. Korotkova Galina B. Slepchenko Olga I. Lipskikh Ekaterina I. Mikhnevich 《Electroanalysis》2023,35(9):e202300054
In this work two strategies for the synthesis of peroxidase silver conjugates for the qualitative and quantitative determination of immunoglobulins (IgG) to ixodid tick-borne borreliosis (ITBB) (Lyme disease) in human serum were proposed. The first approach for Ab-HRP@AgNP conjugate synthesis involved silver nanoparticles (Ag NPs) capped with a commercial peroxidase conjugate (Ab-HRP) by passive adsorption. The second strategy was based on the initial coupling of Ag NPs with human anti-species antibodies (Ab) by passive adsorption followed by the introduction of horseradish peroxidase (HRP) enzyme into the reaction mixture as a blocking reagent for Ab@AgNP@HRP conjugate synthesis. The formation of peroxidase silver conjugates was proved by UV/Vis spectroscopy and Transmission Electron Microscopy (TEM). The catalytic activity of Ab-HRP@AgNP and Ab@AgNP@HRP conjugates was evaluated by Michaelis-Menten kinetics. A commercially available 96-well microtiter plate with recombinant antigens to ITBB was used as a platform for immobilization of analyzed IgG. The HRP in Ab-HRP@AgNP conjugate was found to retain a sufficient level of activity for interaction with the H2O2 substrate to form an intensely colored reaction product. Therefore Ab-HRP@AgNP conjugate can be used in enzyme-linked immunosorbent assay (ELISA) with spectrophotometric detection of 3,3’,5,5’-Tetramethylbenzidine (TMB Ox) for quantitative determination of IgG to ITBB in human serum in the concentration range 12.5–800 ng ml−1 with LOD 2 ng ml−1. Ab@AgNP@HRP conjugate is recommended for the electrochemical determination of IgG to ITBB in human serum at LOD 3 ng ml−1 with registration of silver oxidation by linear sweep anodic stripping voltammetry (LSASV). Ag NPs in Ab-HRP@AgNP and Ab@AgNP@HRP conjugates do not change electrochemical activity during storage and can be used as an electrochemical label in LSASV method in case of HRP inactivation. The immunoassay based on peroxidase silver conjugates expands the analytical potential for the determination of IgG to ITBB especially during the period of increasing incidence. 相似文献