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61.
62.
Bartholomus Pieber Jamal A. Malik Cristian Cavedon Sebastian Gisbertz Aleksandr Savateev Daniel Cruz Tobias Heil Guigang Zhang Peter H. Seeberger 《Angewandte Chemie (International ed. in English)》2019,58(28):9575-9580
Cross‐coupling reactions mediated by dual nickel/photocatalysis are synthetically attractive but rely mainly on expensive, non‐recyclable noble‐metal complexes as photocatalysts. Heterogeneous semiconductors, which are commonly used for artificial photosynthesis and wastewater treatment, are a sustainable alternative. Graphitic carbon nitrides, a class of metal‐free polymers that can be easily prepared from bulk chemicals, are heterogeneous semiconductors with high potential for photocatalytic organic transformations. Here, we demonstrate that graphitic carbon nitrides in combination with nickel catalysis can induce selective C?O cross‐couplings of carboxylic acids with aryl halides, yielding the respective aryl esters in excellent yield and selectivity. The heterogeneous organic photocatalyst exhibits a broad substrate scope, is able to harvest green light, and can be recycled multiple times. In situ FTIR was used to track the reaction progress to study this transformation at different irradiation wavelengths and reaction scales. 相似文献
63.
Florian A. Mann Zhiyi Lv Jrg Großhans Felipe Opazo Sebastian Kruss 《Angewandte Chemie (International ed. in English)》2019,58(33):11469-11473
Fluorescent nanomaterials such as single‐walled carbon nanotubes (SWCNTs) have many advantages in terms of their photophysics, but it is difficult to target them to specific locations in living systems. In contrast, the green fluorescent protein (GFP) has been genetically fused to proteins in many cells and organisms. Therefore, GFP can be seen not only as a fluorophore but as a universal target/handle. Here, we report the conjugation of GFP‐binding nanobodies to DNA‐wrapped SWCNTs. This approach combines the targeting capabilities of GFP‐binding nanobodies and the nonbleaching near‐infrared fluorescence (850–1700 nm) of SWCNTs. These conjugates allow us to track single Kinesin‐5‐GFP motor proteins in developing embryos of Drosophila melanogaster. Additionally, they are sensitive to the neurotransmitter dopamine and can be used for targeted sensing of dopamine in the nm regime. 相似文献
64.
Batyr Garlyyev Kathrin Kratzl Marlon Rück Jan Michali
ka Johannes Fichtner Jan M. Macak Tim Kratky Sebastian Günther Mirza Cokoja Aliaksandr S. Bandarenka Alessio Gagliardi Roland A. Fischer 《Angewandte Chemie (International ed. in English)》2019,58(28):9596-9600
High oxygen reduction (ORR) activity has been for many years considered as the key to many energy applications. Herein, by combining theory and experiment we prepare Pt nanoparticles with optimal size for the efficient ORR in proton‐exchange‐membrane fuel cells. Optimal nanoparticle sizes are predicted near 1, 2, and 3 nm by computational screening. To corroborate our computational results, we have addressed the challenge of approximately 1 nm sized Pt nanoparticle synthesis with a metal–organic framework (MOF) template approach. The electrocatalyst was characterized by HR‐TEM, XPS, and its ORR activity was measured using a rotating disk electrode setup. The observed mass activities (0.87±0.14 A mgPt?1) are close to the computational prediction (0.99 A mgPt?1). We report the highest to date mass activity among pure Pt catalysts for the ORR within similar size range. The specific and mass activities are twice as high as the Tanaka commercial Pt/C catalysis. 相似文献
65.
Jonas Strh Laura Ruiz Arana Philipp Polzin Irma Vania Eliani Patric Lindenberg Niclas Heidenreich Csar dos Santos Cunha Sebastian Leubner Huayna Terraschke 《无机化学与普通化学杂志》2019,645(5):537-543
Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)2(NO3)3] as well as Ce3+‐ and Tb3+‐substituted [La(bipy)2(NO3)3] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)2(NO3)3] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce3+ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce3+ ions, indicating their desolvation and incorporation into the [Ce(bipy)2(NO3)3] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)2(NO3)3] crystallized within days instead of minutes, unless influenced by high Ce3+ and Tb3+ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence. 相似文献
66.
Benjamin A. R. Günther Dr. Sebastian Höfener Dr. Ute Zschieschang Prof. Dr. Hubert Wadepohl Dr. Hagen Klauk Prof. Dr. Lutz H. Gade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(64):14669-14678
A new synthesis of tetraazaperopyrenes (TAPPs) starting from a halogenated perylene derivative 3,4,9,10- tetrabromo-1,6,7,12-tetrachloroperylene ( 1 ) gave access to bay-substituted TAPPs for the first time. Selective lithiation of the bromine-positions and subsequent addition of tosyl azide led to the formation of the tetraazidotetrachloroperylene ( 2 ), which was subsequently reduced by addition of sodium borohydride to the corresponding tetraaminotetrachloroperylene ( 3 ). Oxidation to its semiquinoidal form 4 and subsequent cyclization with acid chlorides gave rise to a series of bay-chlorinated TAPPs. Whereas the aromatic core of the previously studied ortho-substituted TAPPs was found to be planar, the steric pressure of the two chlorine substituents on each side leads to the twist of the peropyrene core of approximately 30 degrees, a structural feature also observed in other bay-substituted perylene derivatives. An experimental and computational analysis reveals that introducing chloride substituents at these positions leads to slightly increased electron affinities (EA) enabling the selective generation and characterization of the reduced mono-anionic radicals and closed shell di-anionic species. These anions were isolated and characterized by UV/Vis spectroscopy and EPR or NMR, respectively. Processing of the bay-chlorinated TAPPs in n-channel organic TFTs revealed electron mobilities of 0.001 to 0.003 cm2 V−1 s−1. These reduced electron mobilities compared to the ortho-halogenated TAPPs are thought to be rooted in the less densely packed solid-state structures. 相似文献
67.
Isabel V. L. Wilkinson Kelly J. Perkins Hannah Dugdale Lee Moir Aini Vuorinen Maria Chatzopoulou Sarah E. Squire Sebastian Monecke Alexander Lomow Marcus Geese Philip D. Charles Peter Burch Jonathan M. Tinsley Graham M. Wynne Stephen G. Davies Francis X. Wilson Fraydoon Rastinejad Shabaz Mohammed Kay E. Davies Angela J. Russell 《Angewandte Chemie (International ed. in English)》2020,59(6):2420-2428
Duchenne muscular dystrophy (DMD) is a fatal muscle‐wasting disease arising from mutations in the dystrophin gene. Upregulation of utrophin to compensate for the missing dystrophin offers a potential therapy independent of patient genotype. The first‐in‐class utrophin modulator ezutromid/SMT C1100 was developed from a phenotypic screen through to a Phase 2 clinical trial. Promising efficacy and evidence of target engagement was observed in DMD patients after 24 weeks of treatment, however trial endpoints were not met after 48 weeks. The objective of this study was to understand the mechanism of action of ezutromid which could explain the lack of sustained efficacy and help development of new generations of utrophin modulators. Using chemical proteomics and phenotypic profiling we show that the aryl hydrocarbon receptor (AhR) is a target of ezutromid. Several lines of evidence demonstrate that ezutromid binds AhR with an apparent KD of 50 nm and behaves as an AhR antagonist. Furthermore, other reported AhR antagonists also upregulate utrophin, showing that this pathway, which is currently being explored in other clinical applications including oncology and rheumatoid arthritis, could also be exploited in future DMD therapies. 相似文献
68.
Weijin Li Song Xue Sebastian Watzele Shujin Hou Johannes Fichtner A. Lisa Semrau Liujiang Zhou Alexander Welle Aliaksandr S. Bandarenka Roland A. Fischer 《Angewandte Chemie (International ed. in English)》2020,59(14):5837-5843
Metal–organic frameworks (MOFs) and their derivatives are considered as promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which are important for many energy provision technologies, such as electrolyzers, fuel cells and some types of advanced batteries. In this work, a “strain modulation” approach has been applied through the use of surface‐mounted NiFe‐MOFs in order to design an advanced bifunctional ORR/OER electrocatalyst. The material exhibits an excellent OER activity in alkaline media, reaching an industrially relevant current density of 200 mA cm?2 at an overpotential of only ≈210 mV. It demonstrates operational long‐term stability even at a high current density of 500 mA cm?2 and exhibits the so far narrowest “overpotential window” ΔEORR‐OER of 0.69 V in 0.1 m KOH with a mass loading being two orders of magnitude lower than that of benchmark electrocatalysts. 相似文献
69.
Song Xue Richard W. Haid Regina M. Kluge Xing Ding Batyr Garlyyev Johannes Fichtner Sebastian Watzele Shujin Hou Aliaksandr S. Bandarenka 《Angewandte Chemie (International ed. in English)》2020,59(27):10934-10938
Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of Pt electrodes in alkaline media by introducing Ni–Fe clusters. As a result, the overpotential needed to achieve a current density of 10 mA cm?2 in H2‐saturated 0.1 m KOH is reduced for the model single‐crystal electrodes down to about 70 mV. To our knowledge, these modified electrodes outperform any other reported electrocatalysts tested under similar conditions. Moreover, the influence of 1) Ni to Fe ratio, 2) cluster coverage, and 3) the nature of the alkali‐metal cations present in the electrolyte on the HER activity has been investigated. The observed catalytic performance likely originates from both the improved water dissociation at the Ni–Fe clusters and the subsequent optimal hydrogen adsorption and recombination at Pt atoms present at the Ni–Fe/Pt boundary. 相似文献
70.
Tobias Schulz Dr. Sebastian Ahrens Dirk Meyer Christoph Allolio Anke Peritz Prof. Dr. Thomas Strassner 《化学:亚洲杂志》2011,6(3):863-867
Owing to numerous new applications, the interest in “task‐specific” ionic liquids increased significantly over the last decade. But, unfortunately, the imidazolium‐based ionic liquids (by far the most frequently used cations) have serious limitations when it comes to modifications of their properties. The new generation of ionic liquids, called tunable aryl–alkyl ionic liquids (TAAILs), replaces one of the two alkyl chains on the imidazolium ring with an aryl ring which allows a large degree of functionalization. Inductive, mesomeric, and steric effects as well as potentially also π π and π π+ interactions provide a wide range of possibilities to tune this new class of ILs. We investigated the influence of electron‐withdrawing and ‐donating substituents at the para‐position of the aryl ring (NO2, Cl, Br, EtO(CO), H, Me, OEt, OMe) by studying the changes in the melting points of the corresponding bromide and bis(trifluoromethanesulfonyl)imide, (N(Tf)2−), salts. In addition, we calculated (B3LYP/6‐311++G(d,p)) the different charge distributions of substituted 1‐aryl‐3‐propyl‐imidazolium cations to understand the experimentally observed effects. The results indicated that the presence of electron‐donating and ‐withdrawing groups leads to strong polarization effects in the cations. 相似文献