Oleg Borodin

Park et al. show that three synthetic ion transporters, SA-3, 8FC4P, and DSC4P-1, promote apoptosis by increasing intracellular sodium and chloride concentrations in cells and consequently inducing osmotic stress. In addition, two of the transporters, SA-3 and 8FC4P, induce autophagy by increasing the cytosolic calcium ion concentration promoted by osmotic stress. However, they eventually inhibit the autophagy process because of their ability to disrupt lysosome function through a transporter-mediated decrease in lysosomal chloride ion concentration and an increase in the lysosomal pH.

Nature, Published online: 20 May 2019; doi:10.1038/d41586-019-01537-4

An unconventional mode of operation allows atomic-force microscope to peer inside 3D shapes.

Macrocyclic molecules and spherical fullerenes: The ease of formation of “nano‐Saturns” is influenced by several factors involving size and shape fitting, and the strength of attractive interactions. Whereas typical belt‐shaped hosts include a guest via π–π interactions, disk‐shaped hosts do so via CH–π interactions and form supramolecular systems the shapes of which are close to that of the planet Saturn.

Abstract

Saturn‐like systems consisting of nanoscale rings and spheres are fascinating motifs in supramolecular chemistry. Several ring molecules are known to include spherical molecules at the center of the cavity via noncovalent attractive interactions. In this Minireview, we generalize the molecular design, the structural features, and the supramolecular chemistry of such “nano‐Saturns”, which consist of monocyclic rings and fullerene spheres (mainly C₆₀), on the basis of previous experimental and theoretical studies. Ring molecules are classified into three types (loop, belt, and disk) according to their shapes and possible interactions. Whereas typical belt‐shaped rings tend to form tight complexes due to the wide contact area via π–π interactions, flat disk‐shaped rings generally form weak complexes due to the narrow contact area mainly via CH–π interactions. In spite of the small association energies, disk‐shaped rings are attractive because such rings can mimic the planet Saturn precisely as exemplified by an anthracene cyclic hexamer–C₆₀ complex.

Nature, Published online: 15 May 2019; doi:10.1038/d41586-019-01493-z

Recognizing the benefits, we move from merely supporting the use of preprint servers to promoting it.

π‐Concave hosts have proven to be an invaluable tool in the purification and application of fullerenes and carbon nanotubes. The unique host–guest shape matching has created a field of research that is dedicated to understanding and maximizing these interactions. Through slight alterations in host design, profound differences in binding emerge. In their Minireview on https://doi.org/10.1002/chem.201806134page 6673 ff., S. Selmani and D. J. Schipper shed light on the dynamic effects of these various changes by providing an overview of the current literature. Furthermore, they offer a checklist of the various factors that can be used to influence the binding of π‐concave hosts with π‐convex carbon nanomaterials.

Molecules and materials that are pushed away from equilibrium can produce unique dynamic and adaptive properties that cannot be attained when they are at rest. In this issue of Chem, Cockroft and co-workers study the transient binding and debinding of coordination cages to the nanopocket of α-hemolysin and show that the binding and debinding events are driven out of equilibrium by an external electric field. Strong applied fields can invert the cage-nanopore binding selectivities and can enhance enantio-inversion to enrich one chiral form of the cage over the other.

The smallest spherical carbon nanocage ([2.2.2]carbon nanocage) so far has been synthesized by the cationic rhodium(I)/H₈‐binap complex‐catalyzed regioselective intermolecular homo‐cyclotrimerization of a cis‐1‐ethynyl‐4‐bromophenyl‐cyclohexadiene derivative, followed by the triple Suzuki–Miyaura cross‐couplings with 1,3,5‐triborylbenzene and reductive aromatization.

Abstract

The smallest spherical carbon nanocage so far, [2.2.2]carbon nanocage, has been synthesized by the cationic rhodium(I)/H₈‐binap complex‐catalyzed regioselective intermolecular cyclotrimerization of a cis‐1‐ethynyl‐4‐arylcyclohexadiene derivative followed by the triple Suzuki–Miyaura cross‐couplings with 1,3,5‐triborylbenzene and reductive aromatization. This cage molecule is highly strained, and its ring strain is between those of [6] and [5]cycloparaphenylenes. A significant red‐shift of an emission maximum was observed, compared with that of known [4.4.4]carbon nanocage. The sequential cyclotrimerizations of a cis‐1,4‐diethynylcyclohexadiene derivative with the same rhodium(I) catalyst followed by reductive aromatization failed to afford [1.1.1]carbon nanocage; instead, a β‐graph‐shaped cage molecule was generated.

Phosphorus‐rich colloidal cobalt diphosphide nanocrystals (CoP₂ NCs) are synthesized via a hot‐injection method. The CoP₂ NCs approach Pt‐like hydrogen‐evolution‐reaction electrocatalytic activity in acidic solution. Moreover, the as‐deposited p‐Si/AZO/TiO₂/CoP₂ with metal–insulator–semiconductor structure shows a remarkable j ₀ of −16.7 mA cm⁻² at 0 V versus RHE and impressive output photovoltage of 0.54 V.

Abstract

Developing earth‐abundant and efficient electrocatalysts for photoelectrochemical water splitting is critical to realizing a high‐performance solar‐to‐hydrogen energy conversion process. Herein, phosphorus‐rich colloidal cobalt diphosphide nanocrystals (CoP₂ NCs) are synthesized via hot injection. The CoP₂ NCs show a Pt‐like hydrogen evolution reaction (HER) electrocatalytic activity in acidic solution with a small overpotential of 39 mV to achieve −10 mA cm⁻² and a very low Tafel slope of 32 mV dec⁻¹. Density functional theory (DFT) calculations reveal that the high P content both physically separates Co atoms to prevent H from over binding to multiple Co atoms, while simultaneously stabilizing H adsorbed to single Co atoms. The catalytic performance of the CoP₂ NCs is further demonstrated in a metal–insulator–semiconductor photoelectrochemical device consisting of bottom p‐Si light absorber, atomic layer deposition Al–ZnO passivation layers, and the CoP₂ cocatalyst. The p‐Si/AZO/TiO₂/CoP₂ photocathode shows a photocurrent density of −16.7 mA cm⁻² at 0 V versus reversible hydrogen electrode (RHE) and an output photovoltage of 0.54 V. The high performance and stability are attributed to the junction between p‐Si and AZO, the corrosion‐resistance of the pinhole‐free TiO₂ protective layer, and the fast HER kinetics of the CoP₂ NCs.

Communications Chemistry, Published online: 06 May 2019; doi:10.1038/s42004-019-0154-z

Self-assembled glycopeptides are increasingly used as biomaterials. Here the self-assembly of glycosylated peptides under crowded conditions is shown to yield laterally aligned fibres which exhibit superior resistance towards non-specific binding of proteins and cells.

Finding a needle in a haystack: We set out to explore the effect of recycling (or recursion) on prebiotic complex mixtures by subjecting the resulting mixture to a recursive environment with the inclusion of different mineral surfaces. Through untargeted analysis of the mixtures, we found that the overall number of products reduces over recursive cycles, while conventionally targeted compounds (such as ribose and uracil) were successfully synthetized under milder conditions than previously reported.

Abstract

One‐pot reactions of simple precursors, such as those found in the formose reaction or formamide condensation, continuously lead to combinatorial explosions in which simple building blocks capable of function exist, but are in insufficient concentration to self‐organize, adapt, and thus generate complexity. We set out to explore the effect of recursion on such complex mixtures by ‘seeding’ the product mixture into a fresh version of the reaction, with the inclusion of different mineral environments, over a number of reaction cycles. Through untargeted UPLC‐HRMS analysis of the mixtures we found that the overall number of products detected reduces as the number of cycles increases, as a result of recursively enhanced mineral environment selectivity, thus limiting the combinatorial explosion. This discovery demonstrates how the involvement of mineral surfaces with simple reactions could lead to the emergence of some building blocks found in RNA, ribose and uracil, under much simpler conditions that originally thought.

Programmable gelators: Tripodal core–arm gelators can be tailor‐made by using covalent and dynamic covalent linkages to form organo‐ and hydrogels. By incorporating arylazopyrazole as photoswitches, the stiffness of the gels can be modulated by light.

Abstract

Versatile photoresponsive gels based on tripodal low molecular weight gelators (LMWGs) are reported. A cyclohexane‐1,3,5‐tricarboxamide (CTA) core provides face‐to‐face hydrogen bonding and a planar conformation, inducing the self‐assembly of supramolecular polymers. The CTA core was substituted with three arylazopyrazole (AAP) arms. AAP is a molecular photoswitch that isomerizes reversibly under alternating UV and green light irradiation. The E isomer of AAP is planar, favoring the self‐assembly, whereas the Z isomer has a twisted structure, leading to a disassembly of the supramolecular polymers. By using tailor‐made molecular design of the tripodal gelator, light‐responsive organogels and hydrogels were obtained. Additionally, in the case of the hydrogels, AAP was coupled to the core through hydrazones, so that the hydrogelator and, hence, the photoresponsive hydrogel could also be assembled and disassembled by using dynamic covalent chemistry.

Polymeric materials containing dynamic covalent bonds, which are capable of exchanging or switching between several molecules, may display properties such as self‐healing and improved malleability, as well as stress‐relaxation and shape‐memory properties. These materials, their intriguing attributes, and potential applications are described in this Minireview.

Abstract

Dynamic covalent bonds (DCBs) have received significant attention over the past decade. These are covalent bonds that are capable of exchanging or switching between several molecules. Particular focus has recently been on utilizing these DCBs in polymeric materials. Introduction of DCBs into a polymer material provides it with powerful properties including self‐healing, shape‐memory properties, increased toughness, and ability to relax stresses as well as to change from one macromolecular architecture to another. This Minireview summarizes commonly used powerful DCBs formed by simple, often “click” reactions, and highlights the powerful materials that can result. Challenges and potential future developments are also discussed.

Diffusion NMR techniques can be used to determine the size of molecules in solution (see figure). Selected examples have allowed the basic principles underlying translational self‐diffusion to be recalled and to derive practical lessons for the accurate manipulation of self‐diffusion coefficients (D _t).

Abstract

Measuring accurate translational self‐diffusion coefficients (D _t) by NMR techniques with modern spectrometers has become rather routine. In contrast, the derivation of reliable molecular information therefrom still remains a nontrivial task. In this paper, two established approaches to estimating molecular size in terms of hydrodynamic volume (V _H) or molecular weight (M) are compared. Ad hoc designed experiments allowed the critical aspects of their application to be explored by translating relatively complex theoretical principles into practical take‐home messages. For instance, comparing the D _t values of three isosteric Cp₂MCl₂ complexes (Cp=cyclopentadienyl, M=Ti, Zr, Hf), having significantly different molecular mass, provided an empirical demonstration that V _H is the critical molecular property affecting D _t. This central concept served to clarify the assumptions behind the derivation of D _t=ƒ(M) power laws from the Stokes–Einstein equation. Some pitfalls in establishing log (D _t) versus log (M) linear correlations for a set of species have been highlighted by further investigations of selected examples. The effectiveness of the Stokes–Einstein equation itself in describing the aggregation or polymerization of differently shaped species has been explored by comparing, for example, a ball‐shaped silsesquioxane cage with its cigar‐like dimeric form, or styrene with polystyrene macromolecules.

Rotating molecules: The role of rotational spectroscopy to investigate non‐covalent interactions by using mass‐ and interaction‐specific molecular aggregates generated and isolated in a supersonic jet expansion is reviewed and examples of recent investigations with halogens, chalcogens, and pnicogens as electrophile partners in R−A⋅⋅⋅B interactions are provided.

Abstract

In the last decade, experiment and theory have expanded our vision of non‐covalent interactions (NCIs), shifting the focus from the conventional hydrogen bond to new bridging interactions involving a variety of weak donor/acceptor partners. Whereas most experimental data originate from condensed phases, the introduction of broadband (chirped‐pulse) microwave fast‐passage techniques has revolutionized the field of rotational spectroscopy, offering unexplored avenues for high‐resolution studies in the gas phase. We present an outlook of hot topics for rotational investigations on isolated intermolecular clusters generated in supersonic jet expansions. Rotational spectra offer very detailed structural data, easily discriminating the isomeric or isotopic composition and effectively cancelling any solvent, crystal, or matrix bias. The direct comparison with quantum mechanical predictions provides insight into the origin of the inter‐ and intramolecular interactions with much greater precision than any other spectroscopic technique, simultaneously serving as test‐bed for fine‐tuning of theoretical methods. We present recent examples of rotational investigations around three topics: oligomer formation, chiral recognition, and identification of halogen, chalcogen, pnicogen, or tetrel bonds. The selected examples illustrate the benefits of rotational spectroscopy for the structural and energetic assessment of inter‐/intramolecular interactions, which may help to move from fundamental research to applications in supramolecular chemistry and crystal engineering.

Pig brains kept alive outside body for hours after death

Pig brains kept alive outside body for hours after death, Published online: 17 April 2019; doi:10.1038/d41586-019-01216-4

Revival of disembodied organs raises slew of ethical and legal questions about the nature of death and consciousness.

Catenanes, molecules comprising two rings held together like links in a chain, can exist as two mirror-image forms if the rings lack bilateral symmetry. These “topological enantiomers” are unusual because they cannot be interconverted by stretching or bending chemical bonds. To date, their synthesis has required the separation of mirror-image structures by specialist techniques. We present a simple method to allow the synthesis of topologically chiral catenanes, opening them up to investigation in catalysis, sensing, and materials science.

Three-year trial shows support for recognizing peer reviewers

Three-year trial shows support for recognizing peer reviewers, Published online: 16 April 2019; doi:10.1038/d41586-019-01162-1

Thousands of Nature referees have chosen to be publicly acknowledged.

Pathway complexity was achieved by chiral molecule 1, which produced chiral expressed single‐handed microcoils by photoinitiated kinetic controlled self‐assembly, pathway B, or ribbon‐like architectures obtained by spontaneous self‐assembly, pathway A, without chiral expression. Distinct competition of molecular interactions among π–π interactions, steric interactions, and chirality transfer is the mainspring of the pathway differentiation (see scheme).

Abstract

Manipulating the self‐assembly pathway is essentially important in the supramolecular synthesis of organic nano‐ and microarchitectures. Herein, we design a series of photoisomerizable chiral molecules, and realize precise control over pathway complexity with external light stimuli. The hidden single‐handed microcoils, rather than the straight microribbons through spontaneous assembly, are obtained through a kinetically controlled pathway. The competition between molecular interactions in metastable photostationary intermediates gives rise to a variety of molecular packing and thereby the possibility of chirality transfer from molecules to supramolecular assemblies.

In this issue of Chem, Cheung et al. have produced armchair (12,12) and chiral (18,12) carbon nanobelts through the Scholl reaction of carbon nanoring precursors. The design of the carbon nanorings is key to the successful synthesis of the carbon nanobelts.

Mechanically interlocked molecular architectures equipped with different types of carbon nanostructures have been a topic of high interest in the last decades. This minireview reports the research work published in the literature and the main advances that have been realized in rotaxane architectures involving fullerenes and carbon nanotubes.

Considerable research efforts have been devoted to the development of rotaxanes and the study of their unique dynamic properties. This minireview provides an overview of the main advances that have been realized in rotaxane architectures involving different types of carbon nanostructures. In particular, rotaxanes based on fullerenes and carbon nanotubes will be discussed.