Ulrich Markel  Daniel F. Sauer  Johannes Schiffels  Jun Okuda  Ulrich Schwaneberg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4500-4511

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Xingchao Dai  Sven Adomeit  Jabor Rabeah  Carsten Kreyenschulte  Angelika Brückner  Hongli Wang  Feng Shi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5305-5309

Glycolic acid (GA), as important building block of biodegradable polymers, has been synthesized for the first time in excellent yields at room temperature by selective oxidation of 1,3‐dihyroxyacetone (DHA) using a cheap supported Cu/Al₂O₃ catalyst with single active Cu^II species. By combining EPR spin‐trapping and operando ATR‐IR experiments, different mechanisms for the co‐synthesis of GA, formates, and formamides have been derived, in which ^.OH radicals formed from H₂O₂ by a Fenton‐like reaction play a key role.  相似文献   

    

Josh Abbenseth  Daniel Delony  Marc C. Neben  Christian Würtele  Bas de&#x;Bruin  Sven Schneider 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6404-6407

The isolable complex [Os(PHMes*)H(PNP)] (Mes*=2,4,6‐^tBu₃C₆H₃; PNP=N{CHCHP^tBu₂}₂) exhibits high phosphinyl radical character. This compound offers access to the phosphinidene complex [Os(PMes*)H(PNP)] by P?H proton coupled electron transfer (PCET). The P?H bond dissociation energy (BDE) was determined by isothermal titration calorimetry and supporting DFT computations. The phosphinidene product exhibits electrophilic reactivity as demonstrated by intramolecular C?H activation.  相似文献   

    

Kapil Shyam Lokare  Beatrice Braun‐Cula  Christian Limberg  Marcel Jorewitz  John T. Kelly  Knut R. Asmis  Stephen Leach  Carsten Baldauf  Itziar Goikoetxea  Joachim Sauer 《Angewandte Chemie (International ed. in English)》2019,58(3):902-906

Even though aluminas and aluminosilicates have found widespread application, a consistent molecular understanding of their surface heterogeneity and the behavior of defects resulting from hydroxylation/dehydroxylation remains unclear. Here, we study the well‐defined molecular model compound, [Al₃(μ₂‐OH)₃(THF)₃(PhSi(OSiPh₂O)₃)₂], 1 , to gain insight into the acid–base reactivity of cyclic trinuclear Al₃(μ₂‐OH)₃ moieties at the atomic level. We find that, like zeolites, they are sufficiently acidic to catalyze the isomerization of olefins. DFT and gas phase vibrational spectroscopy on solvent‐free and deprotonated 1 show that the six‐membered ring structure of its Al₃(μ₂‐OH)₃ core is unstable with respect to deprotonation of one of its hydroxy groups and rearranges into two edge‐sharing four‐membered rings. This renders Al_IV?O(H)?Al_IV units strong acid sites, and all results together suggest that their acidity is similar to that of zeolitic Si_IV?O(H)?Al_IV groups.  相似文献   

    

Ulrich Markel  Daniel F. Sauer  Johannes Schiffels  Jun Okuda  Ulrich Schwaneberg 《Angewandte Chemie (International ed. in English)》2019,58(14):4454-4464

Incorporating artificial metal‐cofactors into protein scaffolds results in a new class of catalysts, termed biohybrid catalysts or artificial metalloenzymes. Biohybrid catalysts can be modified chemically at the first coordination sphere of the metal complex, as well as at the second coordination sphere provided by the protein scaffold. Protein‐scaffold reengineering by directed evolution exploits the full power of nature's diversity, but requires validated screening and sophisticated metal cofactor conjugation to evolve biohybrid catalysts. In this Minireview, we summarize the recent efforts in this field to establish high‐throughput screening methods for biohybrid catalysts and we show how non‐chiral catalysts catalyze reactions enantioselectively by highlighting the first successes in this emerging field. Furthermore, we shed light on the potential of this field and challenges that need to be overcome to advance from biohybrid catalysts to true artificial metalloenzymes.  相似文献   

    

Marc‐Andr Kasper  Maria Glanz  Andreas Stengl  Martin Penkert  Simon Klenk  Tom Sauer  Dominik Schumacher  Jonas Helma  Eberhard Krause  M. Cristina Cardoso  Heinrich Leonhardt  Christian P. R. Hackenberger 《Angewandte Chemie (International ed. in English)》2019,58(34):11625-11630

We describe a new technique in protein synthesis that extends the existing repertoire of methods for protein modification: A chemoselective reaction that induces reactivity for a subsequent bioconjugation. An azide‐modified building block reacts first with an ethynylphosphonite through a Staudinger‐phosphonite reaction (SPhR) to give an ethynylphosphonamidate. The resulting electron‐deficient triple bond subsequently undergoes a cysteine‐selective reaction with proteins or antibodies. We demonstrate that ethynylphosphonamidates display excellent cysteine‐selective reactivity combined with superior stability of the thiol adducts, when compared to classical maleimide linkages. This turns our technique into a versatile and powerful tool for the facile construction of stable functional protein conjugates.  相似文献   

    

Xingchao Dai  Sven Adomeit  Jabor Rabeah  Carsten Kreyenschulte  Angelika Brückner  Hongli Wang  Feng Shi 《Angewandte Chemie (International ed. in English)》2019,58(16):5463-5463

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Maximilian U. Ceblin  Sven Zeller  Benjamin Schick  Dr. Ludwig A. Kibler  Prof. Dr. Timo Jacob 《ChemElectroChem》2019,6(1):3-3

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Thao Hoang-Minh  Jrn Kasbohm  Lan Nguyen-Thanh  Pham Thi Nga  Le Thi Lai  Nguyen Thuy Duong  Nguyen Duc Thanh  Nguyen Thi Minh Thuyet  Dao Duy Anh  Roland Pusch  Sven Knutsson  Rafael Ferreiro Mhlmann 《Journal of Applied Crystallography》2019,52(1):133-147

Transmission electron microscopy linked with energy‐dispersive X‐ray spectroscopy (TEM‐EDX) was applied to characterize mineralogical signals of weathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X‐ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X‐ray diffraction, X‐ray fluorescence and Fourier‐transform infrared spectroscopy (FT‐IR) methods were also applied to verify the TEM‐EDX results. An Excel‐based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100–300 TEM‐EDX analyses as a representative set of individual particles for each sample. The Excel‐based routine involves end members of different clay‐mineral groups and interstratifications with two or three members (e.g. illite–smectite interstratifications – IS‐ml; dioctahedral vermiculite–smectite interstratifications – diVS‐ml; and kaolinite–montmorillonite–dioctahedral vermiculite interstratifications – KSV‐ml). The routine is now freely available. According to the identification procedure, the <2 µm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K‐ and charge‐deficient illite–smectite interstratifications (or diVS‐ml): montmorillonite‐rich randomly ordered (R0) type and illite‐rich regularly ordered (R1) type. Additionally, Fe‐poor KSV‐ml was identified. Industrial Na activation of the Di Linh bentonite resulted in an increase of the R1 diVS‐ml portion and dissolution of a large part of the smectite‐rich phases. The TEM‐EDX approach also gave analytical proof of a sedimentary process for Di Linh smectite. The parent muscovite was altered in two different environments: (i) K‐leaching and layer‐wise alteration into kaolinite (weathering), and (ii) further edge‐controlled alteration of mica into lath‐like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite–mica intergrowths by heat impact (basalt flow).  相似文献   

    

Minh Tuan Duong  David Holz  Muhannad Alkassar  Sven Dittrich  Sigrid Leyendecker 《PAMM》2018,18(1)

This work presents the modelling and simulation of the cardiac electromechanics of a rat left ventricle (LV) under normal and pathological conditions. The 3D LV model is constructed from MRI images of a rat heart. The electrical wave propagates through the whole heart to trigger the mechanical contraction. Our coupled electromechanical problem is formulated based on the mono‐domain and the active stress approach. An implicit finite element‐based method is employed to monolithically solve the problem for the LV. The numerical results show significant differences in the electromechanical behaviour of the healthy and infarcted model.  相似文献