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The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. The thermal isomerization proceeds by linear N inversion, whereas the photoinduced process occurs through CN bond rotation with preferred directionality as a result of diastereoisomerism. Thereby, these imines are arguably the simplest example of synthetic molecular motors. The generality of the orthogonal trajectories of the thermal and photochemical pathways allows for the postulation that every suitable chiral imine qualifies, in principle, as a molecular motor driven by light or heat.

Naturally simple: The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. Based on these studies of configurational switching in imine derivatives, chiral imines such as camphorquinone-based imines are proposed to be the simplest example of synthetic molecular motors.

The functions of life are accomplished by systems exhibiting nonlinear kinetics: autocatalysis, in particular, is integral to the signal amplification that allows for biological information processing. Novel synthetic autocatalytic systems provide a foundation for the design of artificial chemical networks capable of carrying out complex functions. Here we report a set of Fe^II₄L₆ cages containing BODIPY chromophores having tuneable photosensitizing properties. Electron-rich anilines were observed to displace electron-deficient anilines at the dynamic-covalent imine bonds of these cages. When iodoaniline residues were incorporated, heavy-atom effects led to enhanced ¹O₂ production. The incorporation of (methylthio)aniline residues into a cage allowed for the design of an autocatalytic system: oxidation of the methylthio groups into sulfoxides make them electron-deficient and allows their displacement by iodoanilines, generating a better photocatalyst and accelerating the reaction.

Sensitive operation: The incorporation of oxidizable (methylthio)aniline residues in Fe^II₄L₆ cages comprising ¹O₂-sensitizing groups and dynamic-covalent imine bonds led to a system where photooxidation became autocatalytic: transformation of methylthio groups into sulfoxides renders the aniline residues electron-deficient enough for them to be displaced by iodoanilines, generating a better photocatalyst and accelerating the reaction.

The research group of Jean-Marie Lehn recently celebrated its 50th anniversary. Lehn, who shared the Nobel Prize in Chemistry 1987 with Donald J. Cram and Charles J. Pedersen, has been active in many initiatives in the European chemical community, and was instrumental in the founding of Chemistry—A European Journal and ChemBioChem. This Meeting Report summarizes the symposium that was recently held to commemorate the achievements of the Lehn group.

The porphyrin boxes (PB-1 and PB-2), which are rationally designed porous organic cages with a large cavity using well-defined and rigid 3-connected triangular and 4-connected square shaped building units are reported. PB-1 has a cavity as large as 1.95 nm in diameter and shows high chemical stability in a broad pH range (4.8 to 13) in aqueous media. The crystalline nature as well as cavity structure of the shape-persistent organic cage crystals were intact even after complete removal of guest molecules, leading to one of the highest surface areas (1370 m²g⁻¹) among the known porous organic molecular solids. The size of the cavities and windows of the porous organic cages can be modulated using different sized building units while maintaining the topology of the cages, as illustrated with PB-2. Interestingly, PB-2 crystals showed unusual N₂ sorption isotherms as well as high selectivity for CO₂ over N₂ and CH₄ (201 and 47.9, respectively at 273 K at 1 bar).

Find a way: A new strategy for synthesis of shape-persistent organic cages based on porphyrins through rational design is reported. The size of cavities and windows of the organic cages can be modulated using different sized building units while maintaining the topology of the cages.

They’re coming! From Feynman to ribosome mimics, the evolution of artificial molecular machines is told in terms of key inventions and the questions the field continues to face, including design philosophies and what to make and why.

We describe a manganese porphyrin catalyst containing two adjacent cavities, which can be used for the epoxidation of alkenes by sodium hypochlorite. A pyridine ligand bound in one of the cavities regulates the rate and selectivity of the epoxidation reaction that takes place in the adjoining cavity. Pyridine binding studies suggest that site-to-site communication exists between the two cavities. The alkene substrates are completely converted into epoxides by the manganese double-cavity catalyst, but the observed epoxidation rates are low. These low rates are proposed to be a result of the energetically less favourable binding of the substrate into the cavity containing the active site due to an allosteric pinching effect. In the manganese double-cavity arrangement the catalytically active manganese complex is efficiently protected against decomposition, leading to a catalytic system with enhanced stability. The presented work may open a new route to the construction of highly stable catalysts of which the activity and selectivity may eventually be controlled by allosteric interactions.

A highly stable double-cavity-containing catalytic porphyrin host has been developed. A pyridine ligand bound in one of the cavities regulates the rate and selectivity of an epoxidation reaction that takes place in the other cavity. Binding studies suggest that site-to-site communication exists between the two cavities.

Many optoelectronic organic materials are based on donor–acceptor (D–A) systems with heteroatom-containing electron donors. Herein, we introduce a new molecular design for all-carbon curved oligoparaphenylenes as donors, which results in the generation of unique shape-persistent D–A macrocycles. Two types of acceptor-inserted cycloparaphenylenes were synthesized. These macrocycles display positive solvatofluorochromic properties owing to their D–A characteristics, which were confirmed by theoretical and electrochemical studies.

I give this ring: Cycloparaphenylenes bearing acceptor units (anthraquinone and tetracyanoanthraquinodimethane) were synthesized. These macrocycles may be regarded as donor–acceptor (D–A) molecules, as evidenced by their solvatofluorochromic behavior, well-separated HOMO and LUMO, and electrochemical behavior. These findings provide a new molecular design strategy for D–A systems that makes use of curved π-electron ring systems.

The longitudinal extension of cycloparaphenylenes (CPP) towards ultrashort carbon nanotubes (CNTs) is essential for the solution based bottom-up synthesis of CNTs. Herein, the longitudinal extension of the CPP skeleton by the introduction of hexaphenylbenzene units towards polyarylated [n]CPPs is described. Further, the applicability of the Scholl reaction to selectively form graphenic sidewalls is demonstrated. The ring size and substitution patterns of the polyarylated [n]CPPs were varied to overcome strain-induced side reactions during the oxidative cyclodehydrogenation and cyclic para-hexa-peri-hexabenzocoronene trimers ([3]CHBCs) were selectively obtained. This concept is envisioned as an access to ultrashort carbon nanotubes subject to the condition that further benzene rings with the right connectivity will be inserted.

All that it′s cutout to be: Polyarylated [n]cycloparaphenylenes are intermediates on the way to ultra-short carbon nanotubes (CNT). Different polyarylated [n]CPPs can be prepared and their oxidative cyclodehydrogenation leads to CPPs that are cutouts from CNTs.

“…The European Commission decided to launch the Graphene Flagship Project in 2013. The project brings together leading research laboratories from all over Europe with a wide span of different expertise. The Graphene Flagship (together with the Human Brain Project) is the largest collaborative research project that has ever been set up in Europe …” Read more in the Editorial by Andreas Hirsch.