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991.
Barkov Alexey Yu. Kochnev Ivan A. Simonov Nikita S. Kutyashev Igor B. Zimnitskiy Nikolay S. Korotaev Vladislav Yu. Sosnovskikh Vyacheslav Ya. 《Chemistry of Heterocyclic Compounds》2021,57(12):1204-1211
Chemistry of Heterocyclic Compounds - A diastereoselective method was developed for the synthesis of 4-trifluoromethyl- and 4-phenyl-substituted... 相似文献
992.
Nikita S. Gudim Ekaterina A. Knyazeva Ludmila V. Mikhalchenko Ivan S. Golovanov Vadim V. Popov Natalia V. Obruchnikova Oleg A. Rakitin 《Molecules (Basel, Switzerland)》2021,26(16)
This paper presents an improved synthesis of 4,7-dibromobenzo[d][1,2,3]thiadiazole from commercially available reagents. According to quantum-mechanical calculations, benzo[d][1,2,3]thiadiazole (isoBTD) has higher values of ELUMO and energy band gap (Eg), which indicates high electron conductivity, occurring due to the high stability of the molecule in the excited state. We studied the cross-coupling reactions of this dibromide and found that the highest yields of π-spacer–acceptor–π-spacer type compounds were obtained by means of the Stille reaction. Therefore, 6 new structures of this type have been synthesized. A detailed study of the optical and electrochemical properties of the obtained π-spacer–acceptor–π-spacer type compounds in comparison with isomeric structures based on benzo[c][1,2,5]thiadiazole (BTD) showed a red shift of absorption maxima with lower absorptive and luminescent capacity. However, the addition of the 2,2′-bithiophene fragment as a π-spacer resulted in an unexpected increase of the extinction coefficient in the UV/vis spectra along with a blue shift of both absorption maxima for the isoBTD-based compound as compared to the BTD-based compound. Thus, a thorough selection of components in the designing of appropriate compounds with benzo[d][1,2,3]thiadiazole as an internal acceptor can lead to promising photovoltaic materials. 相似文献
993.
Dr. Sebastian Mai Sarah Klingler Dr. Ivan Trentin Julian Kund Marcus Holzer Anastasia Andreeva Dr. Robert Stach Prof. Christine Kranz Prof. Carsten Streb Prof. Boris Mizaikoff Prof. Leticia González 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):17078-17086
We report IR and UV/Vis spectroscopic signatures that allow discriminating between the oxidation states of the manganese-based water oxidation catalyst [(Mn4O4)(V4O13)(OAc)3]3−. Simulated IR spectra show that V=O stretching vibrations in the 900–1000 cm−1 region shift consistently by about 20 cm−1 per oxidation equivalent. Multiple bands in the 1450–1550 cm−1 region also change systematically upon oxidation/reduction. The computed UV/Vis spectra predict that the spectral range above 350 nm is characteristic of the managanese-oxo cubane oxidation state, whereas transitions at higher energy are due to the vanadate ligand. The presence of absorption signals above 680 nm is indicative of the presence of MnIII atoms. Spectroelectrochemical measurements of the oxidation from [Mn Mn ] to [Mn ] showed that the change in oxidation state can indeed be tracked by both IR and UV/Vis spectroscopy. 相似文献
994.
Cristiana Cesari Beatrice Berti Francesco Calcagno Cristina Femoni Marco Garavelli Maria Carmela Iapalucci Ivan Rivalta Stefano Zacchini 《Molecules (Basel, Switzerland)》2021,26(6)
The reaction of [Co(CO)4]− (1) with M(I) compounds (M = Cu, Ag, Au) was reinvestigated unraveling an unprecedented case of polymerization isomerism. Thus, as previously reported, the trinuclear clusters [M{Co(CO)4}2]− (M = Cu, 2; Ag, 3; Au, 4) were obtained by reacting 1 with M(I) in a 2:1 molar ratio. Their molecular structures were corroborated by single-crystal X-ray diffraction (SC-XRD) on isomorphous [NEt4][M{Co(CO)4}2] salts. [NEt4](3)represented the first structural characterization of 3. More interestingly, changing the crystallization conditions of solutions of 3, the hexanuclear cluster [Ag2{Co(CO)4}4]2− (5) was obtained in the solid state instead of 3. Its molecular structure was determined by SC-XRD as Na2(5)·C4H6O2, [PPN]2(5)·C5H12 (PPN = N(PPh3)2]+), [NBu4]2(5) and [NMe4]2(5) salts. 5 may be viewed as a dimer of 3 and, thus, it represents a rare case of polymerization isomerism (that is, two compounds having the same elemental composition but different molecular weights) in cluster chemistry. The phenomenon was further studied in solution by IR and ESI-MS measurements and theoretically investigated by computational methods. Both experimental evidence and density functional theory (DFT) calculations clearly pointed out that the dimerization process occurs in the solid state only in the case of Ag, whereas Cu and Au related species exist only as monomers. 相似文献
995.
Lubo Fical Maria Khalikova Hana Ko
ov Vl
kov Ivona Lhotsk Zuzana Hadysov Ivan Vokl Luk ervený Frantiek vec Lucie Novkov 《Molecules (Basel, Switzerland)》2021,26(8)
Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC. 相似文献
996.
Dr. Yuriy Pihosh Jin Uemura Dr. Ivan Turkevych Dr. Kazuma Mawatari Dr. Yutaka Kazoe Dr. Adelina Smirnova Prof. Takehiko Kitamori 《Angewandte Chemie (International ed. in English)》2017,56(28):8130-8133
Autonomous micro/nano mechanical, chemical, and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro-power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage, and delivery to the sensor. Herein, we realized a solar-light-driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen fuel is then consumed by the μFC to generate electricity. Importantly, the by-product water returns back to the photocatalytic μFG via recirculation loop without losses. Both devices rely on novel phenomena in extended-nano-fluidic channels that ensure ultra-fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ca. 17.2 mWh cm−2 at room temperature. 相似文献
997.
Branko Kozuilić Ivančica Leuštek Branka Pavlović Pavao Mildner Slobodan Barbarić 《Applied biochemistry and biotechnology》1987,15(3):265-278
Each of the three high-mannose type glycoproteins studied, acid phosphatase, invertase, and glucose oxidase, could be specifically
cross-linked through its carbohydrate chains. The procedure involves periodate oxidation of carbohydrate residues followed
by reaction of the generated aldehyde groups with adipic acid dihydrazide as a cross-linker. The amount and size as well as
solubility of the formed polymers could be efficiently controlled by varying the reaction conditions, i.e., the oxidation
degree and the concentrations of glycoproteins, cross-linker, and hydrogen ions during the cross-linking reaction. It was
found that the quantity and size of polymers increased with oxidation degree and protein concentration and by lowering the
pH. When the protein concentration was above and pH below certain values, depending on the glycoenzyme, insoluble polymers
formed. The soluble cross-linked polymers retained a high level of original activity, and the minor decrease in specific activity
noticed was shown to occur during the periodate oxidation step. The cross-linked glycoenzymes are much more resistant to denaturation
by high temperature and by changes in pH, demonstrating the usefulness of this method in preparation of the stabilized glycoprotein
derivatives. 相似文献
998.
Alena A. Volgusheva Daria A. Todorenko Ivan V. Konyukhov Elena N. Voronova Sergey I. Pogosyan Tatyana Yu Plyusnina Sergey S. Khruschev Taras K. Antal 《Photochemistry and photobiology》2023,99(4):1106-1114
The effect of the toxicant 2,3′,4,4′,6-pentachlorobiphenyl (PCB-119) on the growth, chlorophyll content, and PSII activity of C. sorokiniana cells was investigated. A strong negative effect of the toxicant was observed at PCB concentration of 0.05 μg mL−1, when culture growth ceased, chlorophyll strongly bleached, and cell death occurred. The use of original highly sensitive fluorimeter to measure three types of high-resolution chlorophyll fluorescence kinetics allowed us to detect an initial dramatic decrease in the activity of primary photosynthetic reactions, followed by their almost complete recovery at the end of the incubation period when most cells were dead. The study of the distribution of individual cells in culture in terms of Fv/Fm parameter, which reflects the quantum yield of PSII photochemistry, revealed the existence of 2–3% of cells retaining high Fv/Fm (>0.7) in the presence of the toxicant. The treated cultures were able to resume growth after prolonged incubation in fresh medium. The high sensitivity fluorescence methods used made it possible to identify stress-resistant cells which maintain high photosynthetic activity in the presence of lethal doses of toxic substances; these cells provide recovery of the population after stress. 相似文献
999.
David A. Pérez Berrocal Dr. Thimmalapura M. Vishwanatha Dr. Daniel Horn-Ghetko J. Josephine Botsch Laura A. Hehl Dr. Sebastian Kostrhon Dr. Mohit Misra Prof. Dr. Ivan Ðikić Dr. Paul P. Geurink Dr. Hans van Dam Prof. Dr. Brenda A. Schulman Dr. Monique P. C. Mulder 《Angewandte Chemie (International ed. in English)》2023,62(32):e202303319
Protein post-translational modification with ubiquitin (Ub) is a versatile signal regulating almost all aspects of cell biology, and an increasing range of diseases is associated with impaired Ub modification. In this light, the Ub system offers an attractive, yet underexplored route to the development of novel targeted treatments. A promising strategy for small molecule intervention is posed by the final components of the enzymatic ubiquitination cascade, E3 ligases, as they determine the specificity of the protein ubiquitination pathway. Here, we present UbSRhodol, an autoimmolative Ub-based probe, which upon E3 processing liberates the pro-fluorescent dye, amenable to profile the E3 transthiolation activity for recombinant and in cell-extract E3 ligases. UbSRhodol enabled detection of changes in transthiolation efficacy evoked by enzyme key point mutations or conformational changes, and offers an excellent assay reagent amenable to a high-throughput screening setup allowing the identification of small molecules modulating E3 activity. 相似文献
1000.
Haobo Dong Xueying Hu Ruirui Liu Mengzheng Ouyang Hongzhen He Tianlei Wang Xuan Gao Yuhang Dai Wei Zhang Yiyang Liu Yongquan Zhou Dan J. L. Brett Ivan P. Parkin Paul R. Shearing Guanjie He 《Angewandte Chemie (International ed. in English)》2023,62(41):e202311268
For zinc-ion batteries (ZIBs), the non-uniform Zn plating/stripping results in a high polarization and low Coulombic efficiency (CE), hindering the large-scale application of ZIBs. Here, inspired by biomass seaweed plants, an anionic polyelectrolyte alginate acid (SA) was used to initiate the in situ formation of the high-performance solid electrolyte interphase (SEI) layer on the Zn anode. Attribute to the anionic groups of −COO−, the affinity of Zn2+ ions to alginate acid induces a well-aligned accelerating channel for uniform plating. This SEI regulates the desolvation structure of Zn2+ and facilitates the formation of compact Zn (002) crystal planes. Even under high depth of discharge conditions (DOD), the SA-coated Zn anode still maintains a stable Zn stripping/plating behavior with a low potential difference (0.114 V). According to the classical nucleation theory, the nucleation energy for SA-coated Zn is 97 % less than that of bare Zn, resulting in a faster nucleation rate. The Zn||Cu cell assembled with the SA-coated electrode exhibits an outstanding average CE of 99.8 % over 1,400 cycles. The design is successfully demonstrated in pouch cells, where the SA-coated Zn exhibits capacity retention of 96.9 % compared to 59.1 % for bare Zn anode, even under the high cathode mass loading (>10 mg/cm2). 相似文献