Articles

Diatomic C₂ is an elusive species that has only been indirectly observed in the gas phase. It had previously been stabilized in the condensed phase using two ligands, but now a monoligated L→C₂ complex has been prepared with a bulky phosphine ligand (L) bearing two imidazolidin-2-iminato groups. Reactivity studies and theoretical quantum chemical analysis point to the C₂ moiety having a dicarbene character.

Low-temperature scattering leads to the formation of quantum resonances or quasi-bound states, which are observable as peaks in the measured collision cross-sections. Now it has been shown that two different formation mechanisms, quantum tunnelling and quantum reflection, can be distinguished by measuring and comparing elastic and inelastic scattering, which probe the spatial localization of the resonance wavefunctions.

Mirror-symmetry breaking in chiral systems by a chiral solvent has remained poorly understood for decades. Now, the supramolecular polymerization of triphenylene derivatives has shown that—through the additive effects of polymerization—the cumulative entropic effects of the interactions between chiral solvents and solutes create measurable differences in free enthalpy.

Bacteria use thioester-bond-containing proteins to covalently bind to host surfaces and withstand large mechanical shocks. Now, thioester bond reactivity has been shown to be force-dependent: forces >35 pN inhibit bond cleavage by primary amine ligands, whereas forces <6 pN enable reversible reformation. This force-modulated thioester bond reactivity could potentially enable bacterial mobility and a route by which they optimize infection.

Metal–organic frameworks (MOFs) can combine porosity and magnetic order within their lattice, which makes them attractive for the development of stimuli-responsive magnets. Now, a MOF has been prepared that converts from a ferrimagnet to a paramagnet with CO₂ uptake, and returns to the ferrimagnetic state on releasing CO₂.

Artificial systems capable of photocatalytic hydrogen production are not typically based on precisely controlled scaffolds. Now, statistical seeded crystallization of block copolymers—bearing either a pendant cobalt catalyst or a photosensitizer—from solution has been shown to yield recyclable, colloidally stable nanofibres that can be tailored to promote photocatalytic hydrogen production from water.

The self-assembly of haemoglobin-containing erythrocyte membrane fragments onto the surface of preformed coacervates has been used to make hybrid synthetic cells that can initiate nitric-oxide-induced vasodilation. These synthetic cells encapsulate enzymes that generate a flux of nitric oxide, as well as exhibiting high haemocompatibility and increased blood circulation times.

The majority of discrete structures obtained by self-assembly possess high symmetry, and thus low complexity: all subunits relate to their neighbours in a similar manner. Now, the spontaneous formation of complex low-symmetry assemblies produced from a single building block has been demonstrated using a systems chemistry approach. The single building block oligomerizes to form specific homomeric cyclic macromolecules that adopt a folded conformation.

Interactions that generate directed movement in response to a chemical stimulus occur in nature but have been difficult to realize in synthetic systems. Now, it has been shown that asymmetric micelle-mediated exchange of haloalkanes can be used to create tunable chasing interactions between chemically distinct microdroplets. Collective interactions lead to the formation of droplet assemblies with emergent self-organization and collective behaviours.

Nature successfully uses supramolecular assemblies for efficient and robust solar energy harvesting; however, mimicking such material systems for applications in optoelectronic devices has been hampered by stability issues such as the fragility of the supramolecular structures used and the delicate nature of Frenkel excitons. Now, enabled by tunable cage-like scaffolds, stable supramolecular light-harvesting nanotubes have been composed that are robust even under heat stress.

Synthetic oligo-/polyynes with unprecedented length are used to model the elusive carbon allotrope carbyne. Spectroscopic and physical analyses show that endgroups influence the properties of shorter derivatives, but these effects predictably diminish in longer molecules. Molecular symmetry documents the evolution of characteristics from oligoynes to polyynes and offers predictions for the D_∞h structure of carbyne.

Layered COFs are attractive precursors for two-dimensional materials but they are difficult to cleave into mono- or few-layer sheets. Pseudorotaxane moieties have now been embedded into layered COFs to facilitate their cleavage into sheets of uniform thickness. Crown-ether macrocycles within the COF backbone bind to ionic viologen guests, leading to electrostatic repulsion between layers.

Life requires a constant supply of energy, but the energy sources that drove the transition from prebiotic chemistry to biochemistry on the early Earth are unknown. Now, a potentially prebiotic chemical activating reagent has been shown to enable the synthesis, in aqueous conditions and catalysed by small molecules, of peptides, peptidyl–RNAs, RNA oligomers and primordial phospholipids.

Conducting high-resolution, multiplexed imaging in living mammals is challenging because of considerable scattering and autofluorescence in tissue at visible and near-infrared wavelengths. Now, real-time, non-invasive multicolour imaging experiments in live animals have been achieved through the design of optical contrast agents for the shortwave infrared (SWIR, 1,000–2,000 nm) region and the introduction of excitation multiplexing with single-channel SWIR detection.

Silyl-substituted silicon–carbonyl complexes that are stable at room temperature have been prepared by exposure of highly reactive bis(silyl)silylenes to carbon monoxide. The compounds show structural features and reactivity that are reminiscent of their ubiquitous transition-metal–carbonyl counterparts, including π-backbonding and ligand liberation as well as substitution and functionalization reactions.

The controllable functionalization of graphene at the molecular level may prove useful for graphene-based electronics, but is difficult to do in a precise fashion. Now it has been shown that a photocycloaddition reaction between a hydrogen-bonded network of maleimide-derived molecules and single-layer graphene can produce a functionalized array with long-range order.

It is unclear how phospholipid membranes formed on the early Earth, as modern cells synthesize the phospholipid constituents of their membranes enzymatically. Now, a combination of ion pairing and self-assembly has enabled transacylation of lysophospholipids with acyl donors in water, affording a variety of membrane-forming natural diacylphospholipids in high yields.

Metal-catalysed prebiotic reactions have been proposed as forerunners of modern metabolism. Now, an abiotic pathway resembling the reverse tricarboxylic acid cycle has been shown to proceed without metal catalysis. The reaction of glyoxylate and pyruvate produces a series of α-ketoacid tricarboxylic acid analogues, and provides a route to generate α-amino acids by transamination.

Efficient and stable water oxidation catalysts are important if photoelectrochemical cells are to be used to provide clean and sustainable solar fuels. A water oxidation catalyst that operates at neutral pH has now been developed that features ruthenium coordination oligomers anchored onto the surfaces of graphitic materials through CH–π interactions.

In 1949, Winstein and Trifan proposed that the 2-norbornyl cation adopts a bridged, non-classical structure. Now, the generation of an asymmetric environment around the three-centre two-electron bond of such an ion has been reported, enabling highly enantioselective catalytic addition reactions to a simple, non-functionalized non-classical cation.