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61.
Dr. Kristina Sorochkina Dr. Konstantin Chernichenko Prof. Dr. Vladimir V. Zhivonitko Dr. Martin Nieger Prof. Dr. Timo Repo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(61):e202201927
Ortho-phenylene-bridged phosphinoborane (2,6-Cl2Ph)2B-C6H4-PCy2 1 was synthesized in three steps from commercially available starting materials. 1 reacts with H2 or H2O under mild conditions to form corresponding zwitterionic phosphonium borates 1-H2 or 1-H2O . NMR studies revealed both reactions to be remarkably reversible. Thus, when exposed to H2, 1-H2O partially converts to 1-H2 even in the presence of multiple equivalents of water in the solution. The addition of parahydrogen to 1 leads to nuclear spin hyperpolarization both in dry and hydrous solvents, confirming the dissociation of 1-H2O to free 1 . These observations were supported by computational studies indicating that the formation of 1-H2 and 1-H2O from 1 are thermodynamically favored. Unexpectedly, 1-H2O can release molecular hydrogen to form phosphine oxide 1-O . Kinetic, mechanistic, and computational (DFT) studies were used to elucidate the unique “umpolung” water reduction mechanism. 相似文献
62.
Kuznetsov V. V. Podlovchenko B. I. Frolov K. V. Volkov M. A. Khanin D. A. 《Russian Journal of Electrochemistry》2022,58(10):896-906
Russian Journal of Electrochemistry - The composite materials involving platinum nanoparticles on the surface of carbides of Mo, Zr, and Nb are synthesized by the currentless redox reaction between... 相似文献
63.
Svitlana O. Sotnik Artem M. Mishchenko Eduard B. Rusanov Andriy V. Kozytskiy Konstantin S. Gavrilenko Sergey V. Ryabukhin Dmitriy M. Volochnyuk Sergey V. Kolotilov 《Molecules (Basel, Switzerland)》2021,26(12)
The third generation Buchwald precatalysts Pd(ABP)(Phos)(OMs) (also known as Phos Pd G3)) with XPhos and RuPhos were prepared in multigram scale by a modified procedure (ABP = fragment of C-deprotonated 2-aminobiphenyl, XPhos = 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl, RuPhos = 2-dicyclohexylphosphino-2′,6′-diisopropoxybiphenyl, OMs− = CH3SO3−). The 1H- and 31P-NMR spectra of the title complexes and some impurities, measured by various 1D and 2D techniques, were analyzed in detail. The solvent-dependent isomerization of Pd(ABP)(XPhos)(OMs) was studied by NMR, and the X-ray structures of two isomers were determined. The impurities in precatalysts, such as Pd(ABP)(HABP)(OMs) (HABP—neutral 2-aminobiphenyl coordinated to Pd2+ in N-monodentate mode) and PdCl2(XPhos)2, were identified and characterized by single crystal X-ray diffraction. A simple method for the quick quality control (QC) of the precatalysts, suitable for routine use, was proposed. The method was based on the assessment of the impurity content on the basis of the 1H-NMR spectra analysis. 相似文献
64.
Elizaveta D. Gladkova Arina A. Chepanova Ekaterina S. Ilina Alexandra L. Zakharenko Jhannes Reynisson Olga A. Luzina Konstantin P. Volcho Olga I. Lavrik Nariman F. Salakhutdinov 《Molecules (Basel, Switzerland)》2021,26(7)
A new type of berberine derivatives was obtained by the reaction of berberrubine with aliphatic sulfonyl chlorides. The new polycyclic compounds have a sultone ring condensed to C and D rings of a protoberberine core. The reaction conditions were developed to facilitate the formation of sultones with high yields without by-product formation. Thus, it was shown that the order of addition of reagents affects the composition of the reaction products: when sulfochlorides are added to berberrubine, their corresponding 9-O-sulfonates are predominantly formed; when berberrubine is added to pre-generated sulfenes, sultones are the only products. The reaction was shown to proceed stereo-selectively and the cycle configuration was confirmed by 2D NMR spectroscopy. The inhibitory activity of the synthesized sultones and their 12-brominated analogs against the DNA-repair enzyme tyrosyl-DNA phosphodiesterase 1 (Tdp1), an important target for a potential antitumor therapy, was studied. All derivatives were active in the micromolar and submicromolar range, in contrast to the acyclic analogs and 9-O-sulfonates, which were inactive. The significance of the sultone cycle and bromine substituent in binding with the enzyme was confirmed using molecular modeling. The active inhibitors are mostly non-toxic to the HeLa cancer cell line, and several ligands show synergy with topotecan, a topoisomerase 1 poison in clinical use. Thus, novel berberine derivatives can be considered as candidates for adjuvant therapy against cancer. 相似文献
65.
Dmitriy S. Yambulatov Stanislav A. Nikolaevskii Mikhail A. Kiskin Kirill V. Kholin Mikhail N. Khrizanforov Yulia G. Budnikova Konstantin A. Babeshkin Nikolay N. Efimov Alexander S. Goloveshkin Vladimir K. Imshennik Yurii V. Maksimov Evgeny M. Kadilenko Nina P. Gritsan Igor L. Eremenko 《Molecules (Basel, Switzerland)》2021,26(10)
The reaction of the redox active 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) and iron(II) iodide in acetonitrile led to a new complex [(dpp-BIAN)FeIII2] (1). Molecular structure of 1 was determined by the single crystal X-ray diffraction analysis. The spin state of the iron cation in complex 1 at room temperature and the magnetic behavior of 1 in the temperature range of 2–300 K were studied using Mossbauer spectroscopy and magnetic susceptibility measurements, respectively. The neutral character of dpp-BIAN in 1 was confirmed by IR and UV spectroscopy. The electrochemistry of 1 was studied in solution and solid state using cyclic voltammetry. The generation of the radical anion form of the dpp-BIAN ligand upon reduction of 1 in a CH2Cl2 solution was monitored by EPR spectroscopy. 相似文献
66.
Aldar A. Munkuev Evgenii S. Mozhaitsev Arina A. Chepanova Evgeniy V. Suslov Dina V. Korchagina Olga D. Zakharova Ekaterina S. Ilina Nadezhda S. Dyrkheeva Alexandra L. Zakharenko Jhannes Reynisson Konstantin P. Volcho Nariman F. Salakhutdinov Olga I. Lavrik 《Molecules (Basel, Switzerland)》2021,26(11)
Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is a promising target for anticancer therapy due to its ability to counter the effects topoisomerase 1 (Top1) poison, such as topotecan, thus, decreasing their efficacy. Compounds containing adamantane and monoterpenoid residues connected via 1,2,4-triazole or 1,3,4-thiadiazole linkers were synthesized and tested against Tdp1. All the derivatives exhibited inhibition at low micromolar or nanomolar concentrations with the most potent inhibitors having IC50 values in the 0.35–0.57 µM range. The cytotoxicity was determined in the HeLa, HCT-116 and SW837 cancer cell lines; moderate CC50 (µM) values were seen from the mid-teens to no effect at 100 µM. Furthermore, citral derivative 20c, α-pinene-derived compounds 20f, 20g and 25c, and the citronellic acid derivative 25b were found to have a sensitizing effect in conjunction with topotecan in the HeLa cervical cancer and colon adenocarcinoma HCT-116 cell lines. The ligands are predicted to bind in the catalytic pocket of Tdp1 and have favorable physicochemical properties for further development as a potential adjunct therapy with Top1 poisons. 相似文献
67.
Sapozhnikova Irina M. Ulomsky Evgeny N. Rusinov Vladimir L. Chupakhin Oleg N. Stepanov Alexander V. Savateeva-Lyubimova Tatiana N. Sivak Konstantin V. 《Chemistry of Heterocyclic Compounds》2021,57(4):467-472
Chemistry of Heterocyclic Compounds - A series of azolo[5,1-c][1,2,4]triazines containing a cyano group were prepared as analogs of the drug Triazavirin (riamilovir). Sodium... 相似文献
68.
A feasibility study of X‐ray phase‐contrast mammographic tomography at the Imaging and Medical beamline of the Australian Synchrotron 下载免费PDF全文
Yakov I. Nesterets Timur E. Gureyev Sheridan C. Mayo Andrew W. Stevenson Darren Thompson Jeremy M. C. Brown Marcus J. Kitchen Konstantin M. Pavlov Darren Lockie Francesco Brun Giuliana Tromba 《Journal of synchrotron radiation》2015,22(6):1509-1523
Results are presented of a recent experiment at the Imaging and Medical beamline of the Australian Synchrotron intended to contribute to the implementation of low‐dose high‐sensitivity three‐dimensional mammographic phase‐contrast imaging, initially at synchrotrons and subsequently in hospitals and medical imaging clinics. The effect of such imaging parameters as X‐ray energy, source size, detector resolution, sample‐to‐detector distance, scanning and data processing strategies in the case of propagation‐based phase‐contrast computed tomography (CT) have been tested, quantified, evaluated and optimized using a plastic phantom simulating relevant breast‐tissue characteristics. Analysis of the data collected using a Hamamatsu CMOS Flat Panel Sensor, with a pixel size of 100 µm, revealed the presence of propagation‐based phase contrast and demonstrated significant improvement of the quality of phase‐contrast CT imaging compared with conventional (absorption‐based) CT, at medically acceptable radiation doses. 相似文献
69.
70.
The fundamental aspects of charging in electrospray ionization (ESI) are hotly debated. In the present study, ESI charging of DNA oligonucleotides was explored in both positive (ESI+) and negative (ESI?) polarity using mass spectrometry detection. Single‐stranded 12‐mer CCCCAATTCCCC in buffer solution (aqueous NH4Ac, 100 mM) produced similar charge state distribution (CSD) in either ESI+ or ESI?. Similarity of CSD in ESI+ and ESI? was also observed for the double‐stranded 12‐mer CGCGAATTCGCG. By adding typical low‐vapor reagents (e.g. m‐nitro benzyl alcohol, m‐NBA; sulfolane) into the same buffer solution (<0.5% w/v), both CCCCAATTCCCC and CGCGAATTCGCG revealed strong supercharging (SC) effect in ESI?, while very little or no SC effect was observed in ESI+. With either sulfolane or m‐NBA, the CGCGAATTCGCG duplex dissociated into single strands in ESI?. No SC was observed in both ESI+ and ESI? for thermally denatured CGCGAATTCGCG duplex in NH4Ac buffer without the reagents. These findings are difficult to reconcile with the earlier model, which attributes SC in aqueous buffer solution to the conformational changes of analytes. Our observations suggest that the ionic strength of ESI droplets strongly affects the CSD of biopolymers such as DNA oligonucleotides and that SC effect is related to the depletion of ionic strength during the ESI process. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献