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1.
Tatsuro Shirota Narutoshi Mano Masashi Tsuge Kennosuke Hoshina 《Rapid communications in mass spectrometry : RCM》2010,24(5):679-686
The processes of H3O+ production from alcohols (ethanol, 2‐propanol, 1‐propanol, 2‐butanol) and ethers (diethyl ether and ethyl methyl ether), and their deuterium‐substituted species, by intense laser fields (800 nm, 100 fs, ~1 × 1014 W/cm) were investigated through time‐of‐flight (TOF) mass spectrometry. H3O+ formation was observed for all these compounds except for ethyl methyl ether. From the analysis of TOF signals of H(3?n)DnO+ (n = 0, 1, 2, and 3) that have expanding tails with increasing flight time, it has been confirmed that the reaction proceeds through metastable dissociation from the intermediate species C2H(5?m)DmO+(m = 0–5). The common shape of the H(3?n)DnO+ signal profiles contains two major distributions in the time constant, i.e., fast and slow components of <50 ns and ~500 ns, respectively. The H(3?n)DnO+ branching ratio is interpreted to be the result of complete scrambling of four hydrogen atoms at the C? C site in C2H4‐OH+, and partial exchange (18–38%) of a hydrogen atom in the OH group with four other hydrogen atoms within 1 ns prior to H(3?n)DnO+ production. Ab initio calculations for the isomers and transition states of C2H5O+ were also performed, and the observed H(3?n)DnO+ production mechanism has been discussed. In addition, a stable isomer having a complex structure and two isomerization pathways were discovered to contribute to the H3O+ formation process. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
2.
Dongyue Su Jiarui Qi Xiaoman Liu Lei Wang Hao Zhang Hui Xie Xin Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4032-4035
Single‐cell encapsulation has become an effective strategy in cell surface engineering; however, the construction of cell wall‐like layers that allow the switching of the inherent functionality of the engineered cell is still rare. In this study, we show a universal way to create an enzyme‐modulated oxygen‐consuming sandwich‐like layer by using polydopamine, laccase, and tannic acid as building blocks, which then could generate an anaerobic microenvironment around the cell. This layer protected the encapsulated C. pyrenoidosa cell against external stresses and enabled it to switch from normal photosynthetic O2 production to photobiological H2 production. The layer showed an smaller effect on the PSII activity, which contributed a significant enhancement on the rate (0.32 μmol H2 h?1 (mg chlorophyll)?1) and the duration (7 d) of H2 production. This strategy is expected to provide a pathway for modulating the functionality of cells and for breakthroughs in the development of green energy alternatives. 相似文献
3.
Yusuke Isaka Yudai Kawase Yasutaka Kuwahara Kohsuke Mori Hiromi Yamashita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5456-5460
Much effort has been devoted to photocatalytic production of hydrogen peroxide (H2O2) as an alternative to fossil fuels. From an economic point of view, reductive synthesis of H2O2 from O2 coupled with the oxidative synthesis of value‐added products is particularly interesting. We herein report application of MIL‐125‐NH2, a photoactive metal–organic framework (MOF), to a benzylalcohol/water two‐phase system that realized photocatalytic production and spontaneous separation of H2O2 and benzaldehyde. Hydrophobization of the MOF enabled its separation from the aqueous phase. This resulted in enhanced photocatalytic efficiency and enabled application of various aqueous solutions including extremely low pH solution which is favorable for H2O2 production but fatal to MOF structure. In addition, a highly concentrated H2O2 solution was obtained by simply reducing the volume of the aqueous phase. 相似文献
4.
Dr. Allan Jay P. Cardenas Bojana Ginovska Dr. Neeraj Kumar Dr. Jianbo Hou Dr. Simone Raugei Dr. Monte L. Helm Dr. Aaron M. Appel Dr. R. Morris Bullock Dr. Molly O'Hagan 《Angewandte Chemie (International ed. in English)》2016,55(43):13509-13513
The fastest synthetic molecular catalysts for H2 production and oxidation emulate components of the active site of hydrogenases. The critical role of controlled structural dynamics is recognized for many enzymes, including hydrogenases, but is largely neglected in designing synthetic catalysts. Our results demonstrate the impact of controlling structural dynamics on H2 production rates for [Ni(PPh2NC6H4R2)2]2+ catalysts (R=n‐hexyl, n‐decyl, n‐tetradecyl, n‐octadecyl, phenyl, or cyclohexyl). The turnover frequencies correlate inversely with the rates of chair–boat ring inversion of the ligand, since this dynamic process governs protonation at either catalytically productive or non‐productive sites. These results demonstrate that the dynamic processes involved in proton delivery can be controlled through modification of the outer coordination sphere, in a manner similar to the role of the protein architecture in many enzymes. As a design parameter, controlling structural dynamics can increase H2 production rates by three orders of magnitude with a minimal increase in overpotential. 相似文献
5.
Hongwen Zhang Jintao Ming Jiwu Zhao Quan Gu Chao Xu Zhengxin Ding Rusheng Yuan Zizhong Zhang Huaxiang Lin Xuxu Wang Jinlin Long 《Angewandte Chemie (International ed. in English)》2019,58(23):7718-7722
An artificial photosynthetic (APS) system consisting of a photoanodic semiconductor that harvests solar photons to split H2O, a Ni‐SNG cathodic catalyst for the dark reaction of CO2 reduction in a CO2‐saturated NaHCO3 solution, and a proton‐conducting membrane enabled syngas production from CO2 and H2O with solar‐to‐syngas energy‐conversion efficiency of up to 13.6 %. The syngas CO/H2 ratio was tunable between 1:2 and 5:1. Integration of the APS system with photovoltaic cells led to an impressive overall quantum efficiency of 6.29 % for syngas production. The largest turnover frequency of 529.5 h?1 was recorded with a photoanodic N‐TiO2 nanorod array for highly stable CO production. The CO‐evolution rate reached a maximum of 154.9 mmol g?1 h?1 in the dark compartment of the APS cell. Scanning electrochemical–atomic force microscopy showed the localization of electrons on the single‐nickel‐atom sites of the Ni‐SNG catalyst, thus confirming that the multielectron reduction of CO2 to CO was kinetically favored. 相似文献
6.
Hongwen Zhang Jintao Ming Jiwu Zhao Quan Gu Chao Xu Zhengxin Ding Rusheng Yuan Zizhong Zhang Huaxiang Lin Xuxu Wang Jinlin Long 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7800-7804
An artificial photosynthetic (APS) system consisting of a photoanodic semiconductor that harvests solar photons to split H2O, a Ni‐SNG cathodic catalyst for the dark reaction of CO2 reduction in a CO2‐saturated NaHCO3 solution, and a proton‐conducting membrane enabled syngas production from CO2 and H2O with solar‐to‐syngas energy‐conversion efficiency of up to 13.6 %. The syngas CO/H2 ratio was tunable between 1:2 and 5:1. Integration of the APS system with photovoltaic cells led to an impressive overall quantum efficiency of 6.29 % for syngas production. The largest turnover frequency of 529.5 h?1 was recorded with a photoanodic N‐TiO2 nanorod array for highly stable CO production. The CO‐evolution rate reached a maximum of 154.9 mmol g?1 h?1 in the dark compartment of the APS cell. Scanning electrochemical–atomic force microscopy showed the localization of electrons on the single‐nickel‐atom sites of the Ni‐SNG catalyst, thus confirming that the multielectron reduction of CO2 to CO was kinetically favored. 相似文献
7.
Julia Bkowicz Ilona Turowska‐Tyrk 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):o437-o440
The analysis of the crystal structures of rac‐3‐benzoyl‐2‐methylpropionic acid, C11H12O3, (I), morpholinium rac‐3‐benzoyl‐2‐methylpropionate monohydrate, C4H10NO+·C11H11O3−·H2O, (II), pyridinium [hydrogen bis(rac‐3‐benzoyl‐2‐methylpropionate)], C5H6N+·(H+·2C11H11O3−), (III), and pyrrolidinium rac‐3‐benzoyl‐2‐methylpropionate rac‐3‐benzoyl‐2‐methylpropionic acid, C4H10N+·C11H11O3−·C11H12O3, (IV), has enabled us to predict and understand the behaviour of these compounds in Yang photocyclization. Molecules containing the Ar—CO—C—C—CH fragment can undergo Yang photocyclization in solvents but they can be photoinert in the crystalline state. In the case of the compounds studied here, the long distances between the O atom of the carbonyl group and the γ‐H atom, and between the C atom of the carbonyl group and the γ‐C atom preclude Yang photocyclization in the crystals. Molecules of (I) are deprotonated in a different manner depending on the kind of organic base used. In the crystal structure of (III), strong centrosymmetric O...H...O hydrogen bonds are observed. 相似文献
8.
Aleksandra Bocian Adam Gorczyski Dawid Marcinkowski Grzegorz Dutkiewicz Violetta Patroniak Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(4):367-374
The intermolecular interactions in the structures of a series of Schiff base ligands have been thoroughly studied. These ligands can be obtained in different forms, namely, as the free base 2‐[(2E)‐2‐(1H‐imidazol‐4‐ylmethylidene)‐1‐methylhydrazinyl]pyridine, C10H11N5, 1 , the hydrates 2‐[(2E)‐2‐(1H‐imidazol‐2‐ylmethylidene)‐1‐methylhydrazinyl]‐1H‐benzimidazole monohydrate, C12H12N6·H2O, 2 , and 2‐{(2E)‐1‐methyl‐2‐[(1‐methyl‐1H‐imidazol‐2‐yl)methylidene]hydrazinyl}‐1H‐benzimidazole 1.25‐hydrate, C13H14N6·1.25H2O, 3 , the monocationic hydrate 5‐{(1E)‐[2‐(1H‐1,3‐benzodiazol‐2‐yl)‐2‐methylhydrazinylidene]methyl}‐1H‐imidazol‐3‐ium trifluoromethanesulfonate monohydrate, C12H13N6+·CF3O3S?·H2O, 5 , and the dicationic 2‐{(2E)‐1‐methyl‐2‐[(1H‐imidazol‐3‐ium‐2‐yl)methylidene]hydrazinyl}pyridinium bis(trifluoromethanesulfonate), C10H13N52+·2CF3O3S?, 6 . The connection between the forms and the preferred intermolecular interactions is described and further studied by means of the calculation of the interaction energies between the neutral and charged components of the crystal structures. These studies show that, in general, the most important contribution to the stabilization energy of the crystal is provided by π–π interactions, especially between charged ligands, while the details of the crystal architecture are influenced by directional interactions, especially relatively strong hydrogen bonds. In one of the structures, a very interesting example of the nontypical F…O interaction was found and its length, 2.859 (2) Å, is one of the shortest ever reported. 相似文献
9.
Gorączko AJ 《Journal of the American Society for Mass Spectrometry》2011,22(1):187-191
Isotope clusters in library electron ionization mass spectra of germanes often appear a few u lower than theoretically expected
from elemental composition; for example, the dominant peak of the Ge4H10+ pattern is shifted 8 u down. This phenomenon is due to combinations of three essential components: the molecular ion Ge
n
H2n+2+ and two products of hydrogen elimination, Ge
n
H+ and Ge
n
+. Using these components, isotope clusters can be accurately projected for germanium hydrides from Ge2H6 up to Ge5H12. 相似文献
10.
Biotransformation of (±)‐threo‐7,8‐dihydroxy(7,8‐2H2)tetradecanoic acids (threo‐(7,8‐2H2)‐ 3 ) in Saccharomyces cerevisiae afforded 5,6‐dihydroxy(5,6‐2H2)dodecanoic acids (threo‐(5,6‐2H2)‐ 4 ), which were converted to (5S,6S)‐6‐hydroxy(5,6‐2H2)dodecano‐5‐lactone ((5S,6S)‐(5,6‐2H2)‐ 7 ) with 80% e.e. and (5S,6S)‐5‐hydroxy(5,6‐2H2)dodecano‐6‐lactone ((5S,6S)‐5,6‐2H2)‐ 8 ). Further β‐oxidation of threo‐(5,6‐2H2)‐ 4 yielded 3,4‐dihydroxy(3,4‐2H2)decanoic acids (threo‐(3,4‐2H2)‐ 5 ), which were converted to (3R,4R)‐3‐hydroxy(3,4‐2H2)decano‐4‐lactone ((3R,4R)‐ 9 ) with 44% e.e. and converted to 2H‐labeled decano‐4‐lactones ((4R)‐(3‐2H1)‐ and (4R)‐(2,3‐2H2)‐ 6 ) with 96% e.e. These results were confirmed by experiments in which (±)‐threo‐3,4‐dihydroxy(3,4‐2H2)decanoic acids (threo‐(3,4‐2H2)‐ 5 ) were incubated with yeast. From incubations of methyl (5S,6S)‐ and (5R,6R)‐5,6‐dihydroxy(5,6‐2H2)dodecanoates ((5S,6S)‐ and (5R,6R)‐(5,6‐2H2)‐ 4a ), the (5S,6S)‐enantiomer was identified as the precursor of (4R)‐(3‐2H1)‐ and (2,3‐2H2)‐ 6 ). Therefore, (4R)‐ 6 is synthesized from (3S,4S)‐ 5 by an oxidation/keto acid reduction pathway involving hydrogen transfer from C(4) to C(2). In an analogous experiment, methyl (9S,10S)‐9,10‐dihydroxyoctadecanoate ((9S,10S)‐ 10a ) was metabolized to (3S,4S)‐3,4‐dihydroxydodecanoic acid ((3S,4S)‐ 15 ) and converted to (4R)‐dodecano‐4‐lactone ((4R)‐ 18 ). 相似文献
11.
Fabían Orozco Braulio Insuasty John N. Low Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):o220-o225
In each of 6‐amino‐3‐methyl‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one, C9H13N5O3, (I), morpholin‐4‐ium 4‐amino‐2‐(morpholin‐4‐yl)‐5‐nitroso‐6‐oxo‐1,6‐dihydropyrimidin‐1‐ide, C4H10NO+·C8H10N5O3−, (II), and 6‐amino‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one hemihydrate, C8H11N5O3·0.5H2O, (III), the bond distances within the pyrimidine components are consistent with significant electronic polarization, which is most marked in (II) and least marked in (I). Despite the high level of substitution, the pyrimidine rings are all effectively planar, and in each of the pyrimidine components, there are intramolecular N—H...O hydrogen bonds. In each compound, the organic components are linked by multiple N—H...O hydrogen bonds to form sheets of widely differing construction, and in compound (III) adjacent sheets are linked by the water molecules, so forming a three‐dimensional hydrogen‐bonded framework. This study also contains the first direct geometric comparison between the electronic polarization in a neutral aminonitrosopyrimidine and that in its ring‐deprotonated conjugate anion in a metal‐free environment. 相似文献
12.
Zouaoui Setifi Mehdi Boutebdja Fatima Setifi Hocine Merazig Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(7):702-706
In the title compound, catena‐poly[bis[(2,2′‐bipyridine‐κ2N,N′)(1,1,3,3‐tetracyano‐2‐ethoxypropenido‐κN)copper(II)]‐μ4‐hexanedioato‐κ6O1,O1′:O1:O6,O6′:O6], [Cu2(C9H5N4O)2(C6H8O4)(C10H8N2)2]n, the adipate (hexanedioate) dianion lies across a centre of inversion in the space group P. The CuII centre adopts a distorted form of axially elongated (4+2) coordination, and the CuII and adipate components form a one‐dimensional coordination polymer from which the 2,2′‐bipyridine and 1,1,3,3‐tetracyano‐2‐ethoxypropenide components are pendent, and where each adipate dianion is bonded to four different CuII centres. The coordination polymer chains are linked into a three‐dimensional framework structure by a combination of C—H...N and C—H...O hydrogen bonds, augmented by a π–π stacking interaction. 相似文献
13.
Jari T. Kovalainen Elina Wegelius Johannes A. M. Christiaans Juhani Huuskonen Jukka Gynther 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e216-e217
(Cyclohexylmethyloxymethyl)(1H‐imidazol‐4‐iomethyl)‐(S)‐ammonium dichloride, C13H25N3O+·2Cl?, and (4‐bromobenzyl)(1H‐imidazol‐4‐iomethyl)‐(S)‐ammonium dichloride, C13H18BrN3O+·2Cl?, are model compounds with different biological activities for evaluation of the histamine H3‐receptor activation mechanism. Both title compounds occur in almost similar extended conformations. 相似文献
14.
Lionel Kiefer Philippe Dauban Robert H. Dodd Pascal Retailleau 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):o46-o50
The crystal structures of N‐[(1R)‐1‐(1‐naphthyl)ethyl]‐3,4‐dihydro‐2H‐1,2‐benzothiazin‐4‐aminium 1,1‐dioxide chloride, C20H21N2O2S+·Cl−, (I), a six‐membered cyclic sulfonamide, and (1R)‐N‐[(5,5‐dioxo‐6,7‐dihydrodibenzo[d,f][1,2]thiazepin‐7‐yl)methyl]‐1‐(1‐naphthyl)ethanaminium chloride, C26H25N2O2S+·Cl−, (II), a seven‐membered cyclic sulfonamide, both representative of a novel family of agonists of the extracellular calcium sensing receptor (CaSR) of possible clinical importance, are reported. The known chirality of the naphthylethylamine precursor has enabled assignment of the absolute configuration of both compounds, which is crucial for the receptor recognition. The crystal structures, though different, reveal for these agonists a notable absence of intramolecular π–π stacking between their respective aromatic groups. This suggests a common structural feature that allows CaSR agonists to be distinguished from antagonists, since in the latter, such interactions have been shown to be important. The connectivities between molecules in the crystal structures are also different, but both involve hydrogen bonding mediated by chloride ions as a common dominant feature. 相似文献
15.
Mariana Dennehy Fermín Delgado Eleonora Freire Emilia Halac Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(7):572-577
Silver(I) complexes with sulfur‐donor ligands have a broad range of pharmacological applications. One of the most important factors for tuning the biological activity is the type of donor atom and the ease of ligand replacement. Silver thiosaccharinates display a wide range of structures from mono‐ to polynuclear complexes. We report the synthesis, crystal structure and vibrational spectroscopic analysis of a two‐dimensional AgI–thiosaccharinate coordination polymer, namely poly[tris(μ2‐4,4′‐bipyridine‐κ2N:N′)bis(μ3‐1,1‐dioxo‐1,2‐benzisothiazole‐3‐thiolato‐κ3N:S3:S3)bis(μ2‐1,1‐dioxo‐1,2‐benzisothiazole‐3‐thiolato‐κ2S3:S3)tetrasilver(I)], [Ag2(C7H4NO2S2)2(C10H8N2)1.5]n, with 4,4′‐bipyridine acting as a spacer. A relevant feature of the structure is the presence of an unusually short Ag…Ag separation of 2.8859 (10) Å, well within the range of argentophilic interactions and confirmed as such by Raman analysis of the low‐frequency spectrum. From a topological point of view, the structure presents interpenetration in the form of a threefold entangled 2D→2D mesh (2D is two‐dimensional). 相似文献
16.
Multi‐Fluorinated Azido Coumarins for Rapid and Selective Detection of Biological H2S in Living Cells
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Zhentao Zhu Yanyan Li Chao Wei Xin Wen Prof. Dr. Zhen Xi Prof. Dr. Long Yi 《化学:亚洲杂志》2016,11(1):68-71
Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. In order to visualize the endogenous in situ production of H2S in living cells in real time, here we developed multi‐fluorinated azido coumarins as fluorescent probes for the rapid and selective detection of biological H2S. Kinetic studies indicated that an increase in fluorine substitution leads to an increased rate of H2S‐mediated reduction reaction, which is also supported by our theoretical calculations. To our delight, tetra‐fluorinated coumarin 1 could react with H2S fast (t1/2≈1 min) and selectively, which could be further used for continuous enzymatic assays and for visualization of intracellular H2S. Bioimaging results obtained with 1 revealed that d ‐Cys could induce a higher level of endogenous H2S production than l ‐Cys in a time‐dependent manner in living cell. 相似文献
17.
Application of gas chromatography–tandem mass spectrometry (GC/MS/MS) for the analysis of deuterium enrichment of water
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Dillon K. Walker John J. Thaden Nicolaas E. P. Deutz 《Journal of mass spectrometry : JMS》2015,50(6):838-843
Incorporation of deuterium from deuterium oxide (2H2O) into biological components is a commonly used approach in metabolic studies. Determining the dilution of deuterium in the body water (BW) pool can be used to estimate body composition. We describe three sensitive GC/MS/MS methods to measure water enrichment in BW. Samples were reacted with NaOH and U‐13C3‐acetone in an autosampler vial to promote deuterium exchange with U‐13C3‐acetone hydrogens. Headspace injections were made of U‐13C3‐acetone‐saturated air onto a 30‐m DB‐1MS column in electron impact‐mode. Subjects ingested 30 ml 2H2O, and plasma samples were collected. BW was determined by standard equation. Dual‐energy X‐ray absorptiometry scans were performed to calculate body mass, body volume and bone mineral content. A four‐compartmental model was used to estimate body composition (fat and fat free mass). Full‐scan experiments generated an m/z 45 peak and to a lesser extent an m/z 61 peak. Product fragment ions further monitored included 45 and 46 using selected ion monitoring (Method1), the 61 > 45 and 62 > 46 transition using multiple reaction monitoring (MRM; Method2) and the neutral loss, 62 > 45, transition (Method3). MRM methods were optimized for collision energy (CE) and collision‐induced dissociation (CID) argon gas pressure with 6 eV CE and 1.5 mTorr CID gas being optimal. Method2 was used for final determination of 2H2O enrichment of subjects because of lower natural background. We have developed a sensitive method to determine 2H2O enrichment in BW to enable measurement of FM and FFM. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
18.
Wei Huang Qing He Yongpan Hu Yanguang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8768-8772
Conjugated polymers have emerged as promising candidates for photocatalytic H2 production owing to their structural designability and functional diversity. However, the fast recombination of photoexcited electrons and holes limits their H2 production rates. We have now designed molecular heterostructures of covalent triazine frameworks to facilitate charge‐carrier separation and promote photocatalytic H2 production. Benzothiadiazole and thiophene moieties were selectively incorporated into the covalent triazine frameworks as electron‐withdrawing and electron‐donating units, respectively, by a sequential polymerization strategy. The resulting hybrids exhibited much improved charge‐carrier‐separation efficiency as evidenced by photophysical and electrochemical characterization. An H2 evolution rate of 6.6 mmol g?1 h?1 was measured for the optimal sample under visible‐light irradiation (λ>420 nm), which is far superior to that of most reported conjugated‐polymer photocatalysts. 相似文献
19.
Henrik Braband Dr. Yuji Tooyama Thomas Fox Dr. Roger Alberto Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):633-638
Reported herein is a new concept for the labelling of biomolecules with small [99 mTcO3]+ complexes through a [3+2] cycloaddition with alkenes for radiopharmaceutical applications. We developed convenient reactions for the synthesis of small, water stable fac‐[TcO3(tacn‐R)]+ complexes (99Tc and 99mTc, tacn=1,4,7‐triazacyclononane, R=H, ‐CH2‐C6H5, ‐CH2‐C6H4COOH). With alkenes, these high valent [99mTcO3]+ complexes undergo [3+2] cycloaddition with formation of the corresponding TcV–glycolato complexes. The 99mTcV and 99mTcVII complexes are stable at 37 °C in water and in the presence of serum proteins. Therefore, new opportunities in technetium chemistry are enabled with a high potential for medicinal and biological applications. In contrast to classical labelling, the presented strategy is ligand and not metal‐centred. 相似文献
20.
Free Superoxide is an Intermediate in the Production of H2O2 by Copper(I)‐Aβ Peptide and O2
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Dr. Karine Reybier Sara Ayala Dr. Bruno Alies Dr. João V. Rodrigues Susana Bustos Rodriguez Dr. Giovanni La Penna Dr. Fabrice Collin Dr. Cláudio M. Gomes Dr. Christelle Hureau Prof. Dr. Peter Faller 《Angewandte Chemie (International ed. in English)》2016,55(3):1085-1089
Oxidative stress is considered as an important factor and an early event in the etiology of Alzheimer's disease (AD). Cu bound to the peptide amyloid‐β (Aβ) is found in AD brains, and Cu‐Aβ could contribute to this oxidative stress, as it is able to produce in vitro H2O2 and HO. in the presence of oxygen and biological reducing agents such as ascorbate. The mechanism of Cu‐Aβ‐catalyzed H2O2 production is however not known, although it was proposed that H2O2 is directly formed from O2 via a 2‐electron process. Here, we implement an electrochemical setup and use the specificity of superoxide dismutase‐1 (SOD1) to show, for the first time, that H2O2 production by Cu‐Aβ in the presence of ascorbate occurs mainly via a free O2.? intermediate. This finding radically changes the view on the catalytic mechanism of H2O2 production by Cu‐Aβ, and opens the possibility that Cu‐Aβ‐catalyzed O2.? contributes to oxidative stress in AD, and hence may be of interest. 相似文献