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DDC: 660 × Has files: Yes × Publisher: Weinheim : Wiley-VCH × WGL Institute: DWI ×

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Now showing 1 - 10 of 15
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    Enlightening Materials with Photoswitches
    (Weinheim : Wiley-VCH, 2020) Goulet-Hanssens, Alexis; Eisenreich, Fabian; Hecht, Stefan
    Incorporating molecular photoswitches into various materials provides unique opportunities for controlling their properties and functions with high spatiotemporal resolution using remote optical stimuli. The great and largely still untapped potential of these photoresponsive systems has not yet been fully exploited due to the fundamental challenges in harnessing geometrical and electronic changes on the molecular level to modulate macroscopic and bulk material properties. Herein, progress made during the past decade in the field of photoswitchable materials is highlighted. After pointing to some general design principles, materials with an increasing order of the integrated photoswitchable units are discussed, spanning the range from amorphous settings over surfaces/interfaces and supramolecular ensembles, to liquid crystalline and crystalline phases. Finally, some potential future directions are pointed out in the conclusion. In view of the exciting recent achievements in the field, the future emergence and further development of light-driven and optically programmable (inter)active materials and systems are eagerly anticipated. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Pros and Cons : Supramolecular or Macromolecular : What Is Best for Functional Hydrogels with Advanced Properties?
    (Weinheim : Wiley-VCH, 2020) Eelkema, Rienk; Pich, Andrij
    Hydrogels are fascinating soft materials with unique properties. Many biological systems are based on hydrogel-like structures, underlining their versatility and relevance. The properties of hydrogels strongly depend on the structure of the building blocks they are composed of, as well as the nature of interactions between them in the network structure. Herein, gel networks made by supramolecular interactions are compared to covalent macromolecular networks, drawing conclusions about their performance and application as responsive materials. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Mechanistic Insights into the Triplet Sensitized Photochromism of Diarylethenes
    (Weinheim : Wiley-VCH, 2020) Fredrich, Sebastian; Morack, Tobias; Sliwa, Michel; Hecht, Stefan
    Operating photoswitchable molecules repetitively and reliably is crucial for most of their applications, in particular in (opto)electronic devices, and related to reversibility and fatigue resistance, which both critically depend on the photoisomerization mechanism defined by the substitution pattern. Two diarylethene photoswitches bearing biacetyl triplet sensitizers either at the periphery or at the core were investigated using both stationary as well as transient UV/Vis absorption spectroscopy ranging from the femtosecond to the microsecond time scale. The diarylethene with two biacetyl moieties at the periphery is switching predominantly from the triplet excited state, giving rise to an enhanced fatigue resistance. In contrast, the diarylethene bearing one diketone at the photoreactive inner carbon atom cyclizes from the singlet excited state and shows significantly higher quantum yields for both cyclization and cycloreversion. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Polymeric Membranes With Sufficient Thermo‐Mechanical Stability to Deploy Temperature Enhanced Backwash
    (Weinheim : Wiley-VCH, 2021) Aumeier, Benedikt M.; Vollmer, Fabian; Lenfers, Simon; Yüce, Süleyman; Wessling, Matthias
    The alternative membrane cleaning method Temperature Enhanced Backwash exploits elevated temperatures of typically 125 °C to realize high shear rate. This exceeds usual operating temperatures by far. Therefore, the thermo-mechanical properties of polymeric membranes were investigated. A repeated load cycle testing was suited and sensitive to detect the failure of membrane material and potting. All tested PES membranes showed to be stable during the repeated load cycle testing. The potting adhesive may be decisive, thus, a tensile test at 125 °C is proposed. © 2021 The Authors. Chemie Ingenieur Technik published by Wiley-VCH GmbH
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    Computer-Assisted Recombination (CompassR) Teaches us How to Recombine Beneficial Substitutions from Directed Evolution Campaigns
    (Weinheim : Wiley-VCH, 2020) Cui, Haiyang; Cao, Hao; Cai, Haiying; Jaeger, Karl-Erich; Davari, Mehdi D.; Schwaneberg, Ulrich
    A main remaining challenge in protein engineering is how to recombine beneficial substitutions. Systematic recombination studies show that poorly performing variants are usually obtained after recombination of 3 to 4 beneficial substitutions. This limits researchers in exploiting nature's potential in generating better enzymes. The Computer-assisted Recombination (CompassR) strategy provides a selection guide for beneficial substitutions that can be recombined to gradually improve enzyme performance by analysis of the relative free energy of folding (ΔΔGfold). The performance of CompassR was evaluated by analysis of 84 recombinants located on 13 positions of Bacillus subtilis lipase A. The finally obtained variant F17S/V54K/D64N/D91E had a 2.7-fold improved specific activity in 18.3 % (v/v) 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). In essence, the deducted CompassR rule allows recombination of beneficial substitutions in an iterative manner and empowers researchers to generate better enzymes in a time-efficient manner. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Undiscovered Potential: Ge Catalysts for Lactide Polymerization
    (Weinheim : Wiley-VCH, 2020) Rittinghaus, Ruth D.; Tremmel, Jakub; Růžička, Ales; Conrads, Christian; Albrecht, Pascal; Hoffmann, Alexander; Ksiazkiewicz, Agnieszka N.; Pich, Andrij; Jambor, Roman; Herres-Pawlis, Sonja
    Polylactide (PLA) is a high potential bioplastic that can replace oil-based plastics in a number of applications. To date, in spite of its known toxicity, a tin catalyst is used on industrial scale which should be replaced by a benign catalyst in the long run. Germanium is known to be unharmful while having similar properties as tin. Only few germylene catalysts are known so far and none has shown the potential for industrial application. We herein present Ge complexes in combination with zinc and copper, which show amazingly high polymerization activities for lactide in bulk at 150 °C. By systematical variation of the complex structure, proven by single-crystal XRD and DFT calculations, structure–property relationships are found regarding the polymerization activity. Even in the presence of zinc and copper, germanium acts as the active site for polymerizing probably through the coordination–insertion mechanism to high molar mass polymers. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    A Photoclick-Based High-Throughput Screening for the Directed Evolution of Decarboxylase OleT
    (Weinheim : Wiley-VCH, 2021) Markel, Ulrich; Lanvers, Pia; Sauer, Daniel F.; Wittwer, Malte; Dhoke, Gaurao V.; Davari, Mehdi D.; Schiffels, Johannes; Schwaneberg, Ulrich
    Enzymatic oxidative decarboxylation is an up-and-coming reaction yet lacking efficient screening methods for the directed evolution of decarboxylases. Here, we describe a simple photoclick assay for the detection of decarboxylation products and its application in a proof-of-principle directed evolution study on the decarboxylase OleT. The assay was compatible with two frequently used OleT operation modes (directly using hydrogen peroxide as the enzyme's co-substrate or using a reductase partner) and the screening of saturation mutagenesis libraries identified two enzyme variants shifting the enzyme's substrate preference from long chain fatty acids toward styrene derivatives. Overall, this photoclick assay holds promise to speed-up the directed evolution of OleT and other decarboxylases. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Enhancing Robustness of Sortase A by Loop Engineering and Backbone Cyclization
    (Weinheim : Wiley-VCH, 2020) Zou, Zhi; Mate, Diana M.; Nöth, Maximilian; Jakob, Felix; Schwaneberg, Ulrich
    Staphylococcus aureus sortase A (SaSrtA) is widely used for site-specific protein modifications, but it lacks the robustness for performing bioconjugation reactions at elevated temperatures or in presence of denaturing agents. Loop engineering and subsequent head-to-tail backbone cyclization of SaSrtA yielded the cyclized variant CyM6 that has a 7.5 °C increased melting temperature and up to 4.6-fold increased resistance towards denaturants when compared to the parent rM4. CyM6 gained up to 2.6-fold (vs. parent rM4) yield of conjugate in ligation of peptide and primary amine under denaturing conditions. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Co-generation of Ammonia and H2 from H2O Vapor and N2 Using a Membrane Electrode Assembly
    (Weinheim : Wiley-VCH, 2020) Kugler, Kurt; Kriescher, Stefanie M.A.; Giela, Martin; Hosseiny, Schwan; Thimm, Kristof; Wessling, Matthias
    The direct electrochemical synthesis of NH3 from nitrogen and water vapor without the use of a fossil carbon source is highly desired. This synthesis is a viable option to store energy and produce fertilizer precursors. Here, a new Pt-free membrane electrode assembly is presented. An electrochemical membrane reactor demonstrates the feasibility of co-generating NH3 and H2 directly from nitrogen and water vapor at ambient conditions. An unprecedented high NH3-specific current efficiency of up to 27.5% using Ti as cathodic catalyst is reported. The co-generation can be tuned by the balance of process parameters. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Advanced Optical Programming of Individual Meta-Atoms Beyond the Effective Medium Approach
    (Weinheim : Wiley-VCH, 2019) Michel, Ann-Katrin U.; Heßler, Andreas; Meyer, Sebastian; Pries, Julian; Yu, Yuan; Kalix, Thomas; Lewin, Martin; Hanss, Julian; De Rose, Angela; Maß, Tobias W.W.; Wuttig, Matthias; Chigrin, Dmitry N.; Taubner, Thomas
    Nanometer-thick active metasurfaces (MSs) based on phase-change materials (PCMs) enable compact photonic components, offering adjustable functionalities for the manipulation of light, such as polarization filtering, lensing, and beam steering. Commonly, they feature multiple operation states by switching the whole PCM fully between two states of drastically different optical properties. Intermediate states of the PCM are also exploited to obtain gradual resonance shifts, which are usually uniform over the whole MS and described by effective medium response. For programmable MSs, however, the ability to selectively address and switch the PCM in individual meta-atoms is required. Here, simultaneous control of size, position, and crystallization depth of the switched phase-change material (PCM) volume within each meta-atom in a proof-of-principle MS consisting of a PCM-covered Al–nanorod antenna array is demonstrated. By modifying optical properties locally, amplitude and light phase can be programmed at the meta-atom scale. As this goes beyond previous effective medium concepts, it will enable small adaptive corrections to external aberrations and fabrication errors or multiple complex functionalities programmable on the same MS. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim