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71.
Impedimetric Detection of DNA Damage with the Sensor Based on Silver Nanoparticles and Neutral Red 下载免费PDF全文
Yury Kuzin Anna Porfireva Veronika Stepanova Vladimir Evtugyn Ivan Stoikov Gennady Evtugyn Tibor Hianik 《Electroanalysis》2015,27(12):2800-2808
Novel electrochemical DNA‐sensor based on glassy carbon electrode (GCE) modified with Ag nanoparticles, Neutral red covalently attached to its surface and native DNA adsorbed on modifier coating was developed for the estimation of DNA damage on example of model system based on Fenton reagent. As was shown, the oxidation process resulted in synchronous increase of electron transfer resistance and capacitance measured by electrochemical impedance spectroscopy (EIS). The contribution of each sensor component on the signal was specified and sensitivity estimated against similar surface coatings. The shift of EIS parameters was found to be higher than that of similar biosensors reported. The DNA sensor was tested on the estimation of antioxidant capacity of green tea infusions again the results of coulometric titration with electrogenerated bromine. 相似文献
72.
Formal anti‐Carbopalladation Reactions of Non‐Activated Alkynes: Requirements,Mechanistic Insights,and Applications 下载免费PDF全文
M.Sc. Martin Pawliczek Dr. Tobias F. Schneider Dr. Christian Maaß Prof. Dr. Dietmar Stalke Prof. Dr. Daniel B. Werz 《Angewandte Chemie (International ed. in English)》2015,54(13):4119-4123
Formal anti‐carbopalladation reactions of C? C triple bonds are uncommon, but highly useful transformations. Alkynes can be designed to give anti‐carbopalladation products. Prerequisite is the exclusion of other reaction pathways to provoke the cis–trans isomerization of the syn‐carbopalladation intermediate. Detailed mechanistic studies of this crucial step by experimental and computational means were performed. Application of an intramolecular version for the synthesis of oligocyclic compounds and substituted dibenzofurans is also described. 相似文献
73.
Jacob C. Timmerman Bradley D. Robertson Prof. Ross A. Widenhoefer 《Angewandte Chemie (International ed. in English)》2015,54(7):2251-2254
The cationic gold phosphine complex [{PCy2(o‐biphenyl)}Au(NCMe)]+SbF6? (Cy=cyclohexyl) catalyzes the intermolecular, anti‐Markovnikov hydroamination reaction of monosubstituted and cis‐ and trans‐disubstituted alkylidenecyclopropanes (ACPs) with imidazolidin‐2‐ones and other nucleophiles. This reaction forms 1‐cyclopropyl alkylamine derivatives in high yield and with high regio‐ and diastereoselectivity. NMR spectroscopic analysis of gold π‐ACP complexes and control experiments point to the sp hybridization of the ACP internal alkene carbon atom as controlling the regiochemistry of the ACP hydroamination reaction. 相似文献
74.
Direct In Situ Investigation of Milling Reactions Using Combined X‐ray Diffraction and Raman Spectroscopy 下载免费PDF全文
M. Sc. Lisa Batzdorf Dipl.‐Chem. Franziska Fischer Dipl.‐Chem. Manuel Wilke Dipl.‐Ing. Klaus‐Jürgen Wenzel Dr. Franziska Emmerling 《Angewandte Chemie (International ed. in English)》2015,54(6):1799-1802
The combination of two analytical methods including time‐resolved in situ X‐ray diffraction (XRD) and Raman spectroscopy provides a new opportunity for a detailed analysis of the key mechanisms of milling reactions. To prove the general applicability of our setup, we investigated the mechanochemical synthesis of four archetypical model compounds, ranging from 3D frameworks through layered structures to organic molecular compounds. The reaction mechanism for each model compound could be elucidated. The results clearly show the unique advantage of the combination of XRD and Raman spectroscopy because of the different information content and dynamic range of both individual methods. The specific combination allows to study milling processes comprehensively on the level of the molecular and crystalline structures and thus obtaining reliable data for mechanistic studies. 相似文献
75.
76.
Manganese‐Catalyzed Synthesis of cis‐β‐Amino Acid Esters through Organometallic CH Activation of Ketimines 下载免费PDF全文
M. Sc. Weiping Liu M. Sc. Daniel Zell Dr. Michael John Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2015,54(13):4092-4096
Manganese‐catalyzed C? H functionalization reactions of ketimines set the stage for the expedient synthesis of cis‐β‐amino acid esters through site‐ and regioselective alkene annulations. The organometallic C? H activation occurred efficiently with high functional group tolerance, delivering densely functionalized β‐amino acid derivatives with ample scope. 相似文献
77.
Discrimination Between 8‐Oxo‐2′‐Deoxyguanosine and 2′‐Deoxyguanosine in DNA by the Single Nucleotide Primer Extension Reaction with Adap Triphosphate 下载免费PDF全文
Dr. Yosuke Taniguchi Yoshiya Kikukawa Prof. Dr. Shigeki Sasaki 《Angewandte Chemie (International ed. in English)》2015,54(17):5147-5151
The adenosine derivative of 2‐oxo‐1,3‐diazaphenoxazine (Adap) exhibits a superb ability to recognize and form base pairs with 8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG) in duplex DNA. In this study, the triphosphate of Adap (dAdapTP) was synthesized and tested for single nucleotide incorporation into primer strands using the Klenow Fragment. The efficiency of dAdapTP incorporation into 8‐oxo‐dG‐containing templates was more than 36‐fold higher than with dG‐containing templates, and provides better discrimination than does the incorporation of natural 2′‐deoxyadenosine triphosphate (dATP). The selective incorporation of dAdapTP into 8‐oxo‐dG templates was therefore applied to the detection of 8‐oxo‐dG in human telomeric DNA sequences extracted from H2O2‐treated HeLa cells. The enzymatic incorporation of dAdapTP into 8‐oxo‐dG‐containing templates may provide a novel basis for sequencing oxidative DNA damage in the genome. 相似文献
78.
Prof. Dr. Helmut Schwarz 《Angewandte Chemie (International ed. in English)》2015,54(35):10090-10100
Gas‐phase investigations of judiciously doped oxide clusters permit to address fundamental challenges related to, for example, the low‐temperature oxidation of CO or the selective conversion of hydrocarbons. Modifying the size and composition of a free cluster in a controlled way enables the modification of local charge effects and of spin states, and spectroscopic studies in combination with computational work help to identify the active site of a catalyst and to unravel mechanistic details. Also, the interplay of the support material with the reactive part of a composite catalyst cluster can be addressed. Examples will be presented demonstrating how and why the gas‐phase reactivities of heteronuclear clusters, in comparison with their homonuclear counterparts, toward small, generally rather inert molecules can be increased, decreased, or not significantly affected. 相似文献
79.
Christopher B. Kelly Kyle M. Lambert Michael A. Mercadante John M. Ovian Prof. William F. Bailey Prof. Nicholas E. Leadbeater 《Angewandte Chemie (International ed. in English)》2015,54(14):4241-4245
A scalable, high yielding, rapid route to access an array of nitriles from aldehydes mediated by an oxoammonium salt (4‐acetylamino‐2,2,6,6‐tetramethylpiperidine‐1‐oxoammonium tetrafluoroborate) and hexamethyldisilazane (HMDS) as an ammonia surrogate has been developed. The reaction likely involves two distinct chemical transformations: reversible silyl‐imine formation between HMDS and an aldehyde, followed by oxidation mediated by the oxoammonium salt and desilylation to furnish a nitrile. The spent oxidant can be easily recovered and used to regenerate the oxoammonium salt oxidant. 相似文献
80.
Dr. Chang Hyuck Choi Claudio Baldizzone Jan‐Philipp Grote Dr. Anna K. Schuppert Dr. Frédéric Jaouen Dr. Karl J. J. Mayrhofer 《Angewandte Chemie (International ed. in English)》2015,54(43):12753-12757
Fundamental understanding of non‐precious metal catalysts for the oxygen reduction reaction (ORR) is the nub for the successful replacement of noble Pt in fuel cells and, therefore, of central importance for a technological breakthrough. Herein, the degradation mechanisms of a model high‐performance Fe‐N‐C catalyst have been studied with online inductively coupled plasma mass spectrometry (ICP‐MS) and differential electrochemical mass spectroscopy (DEMS) coupled to a modified scanning flow cell (SFC) system. We demonstrate that Fe leaching from iron particles occurs at low potential (<0.7 V) without a direct adverse effect on the ORR activity, while carbon oxidation occurs at high potential (>0.9 V) with a destruction of active sites such as FeNxCy species. Operando techniques combined with identical location‐scanning transmission electron spectroscopy (IL‐STEM) identify that the latter mechanism leads to a major ORR activity decay, depending on the upper potential limit and electrolyte temperature. Stable operando potential windows and operational strategies are suggested for avoiding degradation of Fe‐N‐C catalysts in acidic medium. 相似文献