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Iron is considered as attractive energy carrier in a carbon‐free, circular energy economy. The reduction of iron oxide is crucial for its application as a metal fuel as it determines the efficiency of the cycle. Temperature programmed reduction of α‐Fe2O3 was monitored by complementary X‐ray absorption spectroscopy (XAS) and diffraction (XRD) to obtain the phase composition with high time resolution. Synchrotron Mössbauer spectroscopy (SMS) was additionally employed due to its high sensitivity to the different iron species. Theoretical calculations of surface and bulk adsorption processes were performed to establish the potential reaction pathways and the corresponding energy barriers. A kinetic particle model was then developed to bridge the experimental data and theoretical calculations, which reproduced the reduction onset and behavior. The reduction process was found to be strongly dependent on the heating rate in terms of the reduction window and the observed intermediate species. We propose that a core‐shell mechanism determines the reaction by forming an iron layer which subsequently hinders diffusion of water out of the porous particles leading to some unreduced FeO at high temperature. This study demonstrates the need for complementary methods for describing complex heterogeneous systems and overcoming the chemical sensitivity limitations of any single method. [ABSTRACT FROM AUTHOR]

Ethylene dimerization is an industrial process that is currently carried out using homogeneous catalysts. Here we present a highly active heterogeneous catalyst containing minute amounts of atomically dispersed Pd. It requires no co‐catalyst(s) or activator(s) and significantly outperforms previously reported catalysts tested under similar reaction conditions. The selectivity to C4‐ and C6‐hydrocarbons was about 80 % and 10 % at 42 % ethylene conversion at 200 °C using an industrially relevant feed containing 50 vol % ethylene, respectively. Our kinetic and catalyst characterization experiments complemented by density functional theory calculations provide molecular insights into the local environment of isolated Pd(II)Ox species and their role in achieving high activity in the target reaction. When the developed catalyst was rationally integrated with a Mo‐containing olefin metathesis catalyst in the same reactor, the formed butenes reacted with ethylene to propylene with a selectivity of 98 % at about 24 % ethylene conversion. [ABSTRACT FROM AUTHOR]

Die Ethylen‐Dimerisierung ist ein industrieller Prozess, der derzeit mit homogenen Katalysatoren durchgeführt wird. Hier stellen wir einen hochaktiven heterogenen Katalysator vor, der winzige Mengen von atomar dispergiertem Pd enthält. Er erfordert keine Cokatalysatoren oder Aktivatoren und übertrifft die Leistung früherer Katalysatoren, die unter ähnlichen Reaktionsbedingungen getestet wurden. Die Selektivität für C4‐ und C6‐Kohlenwasserstoffe betrug bei 200 °C etwa 80 % bzw. 10 % bei 42 % C2H4‐Umsatz unter Verwendung eines industriell relevanten Reaktionsgemisches mit 50 Vol.‐% Ethylen. Unsere Experimente zur Kinetik und Katalysatorcharakterisierung, ergänzt durch Dichtefunktionaltheorie‐Berechnungen, liefern molekulare Einblicke in die lokale Umgebung isolierter Pd(II)Ox‐Spezies und ihre Rolle bei der Erzielung einer hohen Aktivität in der Zielreaktion. Als der entwickelte Katalysator rationell mit einem Mo‐haltigen Olefinmetathesekatalysator im gleichen Reaktor integriert wurde, reagierten die gebildeten Butene mit Ethylen zu Propylen mit einer Selektivität von 98 % bei etwa 24 % C2H4‐Umsatz. [ABSTRACT FROM AUTHOR]

A novel buckybowl catcher with an extended π‐surface has been synthesized via cross‐coupling of two bowl shaped bromoindacenopicene moieties with a tolyl linker. The obtained catcher has been unambiguously characterized by 2D‐NMR and mass spectrometry. DFT calculations indicate that the curved shape of the receptor moieties is favourable for binding fullerenes. Effective binding was confirmed for interactions with C60 and C70 utilizing NMR spectroscopy and isothermal titration calorimetry (ITC). The resulting binding values show a higher affinity of the catcher towards C70 over C60. The designed catcher demonstrated the fundamental possibility of creating sensors for spherical aromaticity. [ABSTRACT FROM AUTHOR]

The synthesis of pristine non‐planar nanographenes (NGs) via a cyclodehydrofluorination strategy is reported and the creation of highly strained systems via alumina‐assisted C−F bond activation is shown. Steric hindrance could execute an alternative coupling program leading to rare octagon formation offering access to elusive non‐classical NGs. The combination of two alternative ways of folding could lead to the formation of various 3D NG objects, resembling the Japanese art of origami. The power of the presented "origami" approach is proved by the assembly of 12 challenging nanographenes that are π‐isoelectronic to planar hexabenzocoronene but forced out of planarity. [ABSTRACT FROM AUTHOR]

The synthesis of an unprecedented, π‐extended hexabenzocorene (HBC)‐based diaza[7]helicene is presented. The target compound was synthesized by an ortho‐fusion of two naphthalene diimide (NDI) units to a HBC‐skeleton. A combination of Diels–Alder and Scholl‐type oxidation reactions involving a symmetric di‐NDI‐tolane precursor were crucial for the very selective formation of the helical superstructure via a hexaphenyl‐benzene (HPB) derivative. The formation of the diaza[7]helicene moiety in the final Scholl oxidation is favoured, affording the symmetric π‐extended helicene as the major product as a pair of enantiomers. The separation of the enantiomers was successfully accomplished by HPLC involving a chiral stationary phase. The absolute configuration of the enantiomers was assigned by comparison of circular dichroism spectra with quantum mechanical calculations. [ABSTRACT FROM AUTHOR]

The synthesis of a new type of chiral and dynamic nonplanar aromatics containing a combination of fused perylene‐based coronenes and helicenes is reported. Either one or two helicene moieties were fused to the bay regions of an extended perylene core. The target compounds contain either identical or two different helicene building blocks. The combination with two helicene units leads to six different isomers, including two pairs of enantiomers and two meso forms. The experimental determination of the isomerization barriers the corresponding double [5]‐helicenes revealed activation energies of Ea=24.81 and 25.38 kcal mol−1, which is slightly above the barrier of the parent [5]‐helicene. Resolution of all possible regio‐ and stereoisomers allowed for the systematic investigation of the chiroptical properties. They revealed remarkable dissymmetry factors IgabsI of up to 1.2×10−2, which mirror the synergy between the strong absorbing perylenes and the inherent chirality of helicenes. [ABSTRACT FROM AUTHOR]

In contrast to catalytically active metal single atoms deposited on oxide nanoparticles, the crystalline nature of metal‐organic frameworks (MOFs) allows for a thorough characterization of reaction mechanisms. Using defect‐free HKUST‐1 MOF thin films, we demonstrate that Cu+/Cu2+ dimer defects, created in a controlled fashion by reducing the pristine Cu2+/Cu2+ pairs of the intact framework, account for the high catalytic activity in low‐temperature CO oxidation. Combining advanced IR spectroscopy and density functional theory we propose a new reaction mechanism where the key intermediate is an uncharged O2 species, weakly bound to Cu+/Cu2+. Our results reveal a complex interplay between electronic and steric effects at defect sites in MOFs and provide important guidelines for tailoring and exploiting the catalytic activity of single metal atom sites. [ABSTRACT FROM AUTHOR]

Im Gegensatz zu einzelnen, auf Oxid‐Nanopartikeln deponierten katalytisch aktiven Metalllatomen erlaubt die kristalline Beschaffenheit metallorganischer Gerüstverbindungen (MOFs) eine genaue Charakterisierung der Reaktionsmechanismen. Ausgehend von zunächst defektfreien HKUST‐1‐MOF‐Dünnschichten zeigen wir, dass Cu+/Cu2+‐Dimerdefekte, die kontrolliert durch Reduktion der reinen Cu2+/Cu2+‐Paare des intakten Gerüsts erzeugt wurden, die hohe katalytische Aktivität für die Tieftemperatur‐CO‐Oxidation erklären. Mit Hilfe der In‐situ‐IR‐Spektroskopie und der Dichtefunktionaltheorie konnte der Reaktionsmechanismus identifiziert werden. Dabei ist das wichtigste Zwischenprodukt eine ungeladene, schwach an Cu+/Cu2+ gebundene O2‐Spezies. Unsere Ergebnisse zeigen ein komplexes Zusammenwirken elektronischer und sterischer Effekte an Defekten in MOFs und liefern wichtige Richtlinien zur Einstellung und optimalen Nutzung der katalytischen Aktivität einzelner Metallatome. [ABSTRACT FROM AUTHOR]

A superhalogen F@C20(CN)20 and a corresponding Brønsted superacid were designed and investigated on DFT and DLPNO‐CCSD(T) levels of theory. Calculated compounds have outstanding electron affinity and deprotonation energy, respectively. We consider superacid H[F@C20(CN)20] to be able to protonate molecular nitrogen. The stability of these structures is discussed, while some of the previous predictions concerning neutral Brønsted superacids of record strength are doubted. © 2019 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of a novel buckybowl catcher that has a high affinity for C70 fullerene molecules. The catcher, made by cross-coupling two bowl-shaped bromoindacenopicene moieties with a tolyl linker, demonstrates the potential for creating sensors for spherical aromaticity. The researchers describe the catcher as a "miraculous, marvelous Fabergé artwork" that carefully frames the C70 fullerene. The full research article provides more information on this topic. [Extracted from the article]

Hexa- peri-hexabenzocoronides (HBC) was successfully used as a model system for investigating the complex mechanism of the reductive functionalization of graphene. The well-defined molecular HBC system enabled deeper insights into the mechanism of the alkylation of reductively activated nanographenes. The separation and complete characterization of alkylation products clearly demonstrate that nanographene functionalization proceeds with exceptionally high regio- and stereoselectivities on the HBC scaffold. Experimental and theoretical studies lead to the conclusion that the intact basal graphene plane is chemically inert and addend binding can only take place at either preexisting defects or close to the periphery. [ABSTRACT FROM AUTHOR]

We report on the synthesis and the structure elucidation of the elusive azafullerene pentachloride C59NCl5, which was obtained by high temperature halogenation of (C59N)2. The exceptionally strong host-guest interaction of the title compound in the solid is discussed. [ABSTRACT FROM AUTHOR]

Carbon origami, C-F bond activation, multihelical nanographenes, aryl-aryl coupling, cyclodehydrofluorination Cover Feature: Carbon Origami via an Alumina-Assisted Cyclodehydrofluorination Strategy (Chem. Eur. J. 20/2021) Keywords: aryl-aryl coupling; carbon origami; C-F bond activation; cyclodehydrofluorination; multihelical nanographenes EN aryl-aryl coupling carbon origami C-F bond activation cyclodehydrofluorination multihelical nanographenes 6103 6103 1 04/09/21 20210407 NES 210407 B Rational folding of nanographenes b has the potential to penetrate the barrier between macro- and micro-worlds for the engineering of carbon-based materials with functional molecular shapes. [Extracted from the article]

Cover Feature: -Extended Diaza[7]helicenes by Hybridization of Naphthalene Diimides and Hexa-peri-hexabenzocoronenes (Chem. Eur. J. 7/2021) Keywords: chirality; helicene; hexabenzocoronene; naphthalene; -extension EN chirality helicene hexabenzocoronene naphthalene -extension 2222 2222 1 02/03/21 20210201 NES 210201 B A hexa- I peri i -hexabenzocoronen based diaza[7]helicene b was synthesized featuring a wide lateral -extension of the inner helix. Chirality, helicene, hexabenzocoronene, naphthalene, -extension. [Extracted from the article]

Keywords: dynamic; helicene; isomerization; isomers; perylene EN dynamic helicene isomerization isomers perylene 1 1 1 11/12/20 20201106 NES 201106 B Mono and double helicene-coronene hybrids b were prepared by Pd-catalyzed cross-coupling and photocyclization reactions. Temperature-dependent NMR experiments and DFT calculations shed light on the inversion process of the helicenes and revealed a two-step isomerization pathway. Dynamic, helicene, isomerization, isomers, perylene. [Extracted from the article]

The azafullerene pentachloride C59NCl5 obtained by high temperature halogenation of (C59N)2 displays unprecedented and effective supramolecular bonding to the fullerene “surface”. The cumulative effect of five chloro‐π interactions leads to an effective 1D host–guest stacking in the solid state. The pentachlorinated addition pattern serves as a “receptor” of the bowl‐shaped corannulene fragment and thus appears to be prospective for possible recognition of fullerenes and related geodesic PAH structures. More information can be found in the Communication by K. Yu. Amsharov, A. Hirsch et al. on page 9014. [ABSTRACT FROM AUTHOR]

We report on the synthesis and the structure elucidation of the elusive azafullerene pentachloride C59NCl5, which was obtained by high temperature halogenation of (C59N)2. The exceptionally strong host-guest interaction of the title compound in the solid is discussed. [ABSTRACT FROM AUTHOR]