Silaffins are uniquely modified peptides that have been implicated in the biogenesis of diatom biosilica. A method that avoids the harsh anhydrous hydrogen fluoride treatment commonly used to dissolve biosilica allows the extraction of silaffins in their native state. The native silaffins carry further posttranslational modifications in addition to their polyamine moieties. Each serine residue was phosphorylated, and this high level of phosphorylation is essential for biological activity. The zwitterionic structure of native silaffins enables the formation of supramolecular assemblies. Time-resolved analysis of silica morphogenesis in vitro detected a plastic silaffin-silica phase, which may represent a building material for diatom biosilica.

Highly effective electrocatalysts promoting CO 2 reduction reaction (CO 2 RR) is extremely desirable to produce value-added chemicals/fuels while addressing current environmental challenges. Herein, we develop a layer-stacked, bimetallic two-dimensional conjugated metalorganic framework (2D c-MOF) with copper-phthalocyanine as ligand (CuN 4) and zinc-bis (dihydroxy) complex (ZnO 4) as linkage (PcCu-O 8-Zn). The PcCu-O 8-Zn exhibits high CO selectivity of 88%, turnover frequency of 0.39 s −1 and long-term durability (>10 h), surpassing thus by far reported MOF-based electrocatalysts. The molar H 2 /CO ratio (1:7 to 4:1) can be tuned by varying metal centers and applied potential, making 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; ZnO 4 complexes act as CO 2 RR catalytic sites while CuN 4 centers promote the protonation of adsorbed CO 2 during CO 2 RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO 2 RR toward syngas synthesis.

Diatoms are eukaryotic, unicellular algae that are ubiquitously present in almost any water habitat on earth. Diatoms dominate phytoplankton populations and algal blooms in the oceans. They are responsible for about 25 % of the world's net primary production. Apart from this ecological significance, diatoms are mainly known for the intricate geometries and spectacular patterns of their silica‐based cell walls. These patterns are species specific. They are precisely reproduced in each generation documenting a genetic control of this biomineralization process. Biogenesis of the diatom cell wall is considered to be a paradigm for the controlled production of nanostructured silica. Biochemical studies demonstrated that diatom biosilica is a composite material containing zwitterionic proteins (silaffins) and long‐chain polyamines in addition to silica. Functional studies indicate a crucial role of these organic components in guiding silica precipitation as well as in the formation of species‐specific nanopatterns. These activities can be explained by molecular self‐assembly and phase‐separation processes. Moreover, diatom cell walls also exhibit very exciting properties from the physical point of view: they are extremely stable and they may act as photonic crystals.

A two‐dimensional (2D) sp2‐carbon‐linked conjugated polymer framework (2D CCP‐HATN) has a nitrogen‐doped skeleton, a periodical dual‐pore structure and high chemical stability. The polymer backbone consists of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon–carbon double bonds. Profiting from the shape‐persistent framework of 2D CCP‐HATN integrated with the electrochemical redox‐active HATN and the robust sp2 carbon‐carbon linkage, 2D CCP‐HATN hybridized with carbon nanotubes shows a high capacity of 116 mA h g−1, with high utilization of its redox‐active sites and superb cycling stability (91 % after 1000 cycles) and rate capability (82 %, 1.0 A g−1 vs. 0.1 A g−1) as an organic cathode material for lithium‐ion batteries.

Organic electrode materials are of long‐standing interest for next‐generation sustainable lithium‐ion batteries (LIBs). As a promising cathode candidate, imide compounds have attracted extensive attention due to their low cost, high theoretical capacity, high working voltage, and fast redox reaction. However, the redox active site utilization of imide electrodes remains challenging for them to fulfill their potential applications. Herein, the synthesis of a highly stable, crystalline 2D polyarylimide (2D‐PAI) integrated with carbon nanotube (CNT) is demonstrated for the use as cathode material in LIBs. The synthesized polyarylimide hybrid (2D‐PAI@CNT) is featured with abundant π‐conjugated redox‐active naphthalene diimide units, a robust cyclic imide linkage, high surface area, and well‐defined accessible pores, which render the efficient utilization of redox active sites (82.9%), excellent structural stability, and fast ion diffusion. As a consequence, high rate capability and ultrastable cycle stability (100% capacity retention after 8000 cycles) are achieved in the 2D‐PAI@CNT cathode, which far exceeds the state‐of‐the‐art polyimide electrodes. This work may inspire the development of novel organic electrodes for sustainable and durable rechargeable batteries.

π-Conjugated two-dimensional covalent organic frameworks (2D COFs) are emerging as a novel class of electroactive materials for (opto)­electronic and chemiresistive sensing applications. However, understanding the intricate interplay between chemistry, structure, and conductivity in π-conjugated 2D COFs remains elusive. Here, we report a detailed characterization for the electronic properties of two novel samples consisting of Zn– and Cu–phthalocyanine-based pyrazine-linked 2D COFs. These 2D COFs are synthesized by condensation of metal–phthalocyanine (M = Zn and Cu) and pyrene derivatives. The obtained polycrystalline-layered COFs are p-type semiconductors both with a band gap of ∼1.2 eV. A record device-relevant mobility up to ∼5 cm2/(V s) is resolved in the dc limit, which represents a lower threshold induced by charge carrier localization at crystalline grain boundaries. Hall effect measurements (dc limit) and terahertz (THz) spectroscopy (ac limit) in combination with density functional theory (DFT) calculations demonstrate that varying metal center from Cu to Zn in the phthalocyanine moiety has a negligible effect in the conductivity (∼5 × 10–7 S/cm), charge carrier density (∼1012 cm–3), charge carrier scattering rate (∼3 × 1013 s–1), and effective mass (∼2.3m 0) of majority carriers (holes). Notably, charge carrier transport is found to be anisotropic, with hole mobilities being practically null in-plane and finite out-of-plane for these 2D COFs.

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The synthesis and structure of a new flexible metal-organic framework Ni(2)(2,6-ndc)(2)(dabco) (DUT-8(Ni), DUT = Dresden University of Technology, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane) as well as its characterization by gas adsorption and (129)Xe NMR spectroscopy is described. The compound shows reversible structural transformation without loss of crystallinity upon solvent removal and physisorption of several gases. Xenon adsorption studies combined with (129)Xe NMR spectroscopy turn out to be favorable methods for the detection and characterization of the so-called "gate-pressure" effect in this novel MOF material. The linewidth and chemical shift of the (129)Xe NMR signal are shown to be very sensitive parameters for the detection of this structural transition from a narrow pore system with low porosity to a wide pore state. The transition and threshold temperature is clearly detected.