Volume 8 Issue 7, July 2016

Michelle Francl wonders if more chemists should be reading science fiction on the job.

The calcination of metal–organic framework (MOF) precursors is promising for the preparation of nanoscale carbon materials, but the resulting morphologies have remained limited. Now, controlling the growth of precursor MOFs has enabled 1D carbon nanorods to be fabricated — these can then be readily unravelled into 2D graphene nanoribbons.

Nitric oxide (NO) has important functions in all forms of life and serves, for example, as a signalling molecule in mammals. Now, two complementary studies have uncovered how NO binds to blue copper proteins. This research suggests a mechanism by which NO could regulate the activity of blue copper proteins involved in denitrification.

Combining conventional transition-metal oxidation with oxygen oxidation in 'lithium-excess' materials is a recently discovered route to improving the capacity of lithium-ion batteries. Now two studies, one experimental and one theoretical, have investigated the processes, states and structures involved.

Numerous dynamic molecular crystals whose physical properties can be switched by external stimuli have recently been developed. This Review discusses how the precise control of the electron, proton and molecular movement within the crystals through the application of external stimuli can lead to considerable changes in their properties.

Quasicrystalline materials exhibit long-range order but no translational periodicity. Now, a random tiling quasicrystal has been fabricated on a Au(111) surface by coordination interactions between europium centres and linear dicarbonitrile linkers under stoichiometry control. The 2D metal–organic network exhibits the simultaneous presence of four-, five- and six-fold vertices and dodecagonal symmetry.

NO participates in numerous physiological processes of which many involve the reaction of NO with metalloenzymes to form a metal–nitrosyl (M–NO). Now, addition of NO to models of type 1 Cu sites has provided a fully characterized S-nitrosothiol adduct, [Cu^I](κ¹-N(O)SR), that reversibly loses NO upon purging with an inert gas. These findings suggest a new motif for reversible binding of nitric oxide at bioinorganic metal centres.

S-Nitrosylation has emerged as an important pathway for dynamic post-translational regulation of many classes of proteins. Now, the reversible insertion of NO into a copper–thiolate bond has been observed under physiologically relevant conditions using an engineered azurin. DFT calculation indicates that the reaction proceeds via a radical combination mechanism.

The single-bond-resolved chemical structures of transient intermediates in a complex bimolecular reaction cascade were imaged by noncontact atomic force microscopy. Theoretical simulations reveal that the kinetic stabilization of experimentally observable intermediates is governed by selective energy dissipation to the substrate and entropic changes along the reaction pathway.

The energy that can be stored in lithium-ion batteries is typically limited by the redox chemistry of the transition metals within the cathodes. Now it is shown that for Li_1.2[Ni²⁺_0.13Co³⁺_0.13Mn⁴⁺_0.54]O₂, a 3d-transition-metal oxide that breaks this limit, Li-ion extraction is charge compensated not just by transition-metal oxidation but also through the generation of localized electron-holes on oxygen.

The chemistry of the transition metals within the oxide cathodes of lithium-ion batteries typically limits their capacity, however, reversible oxygen redox could potentially break this limit. It is now demonstrated that Li-excess and cation disorder create specific environments around oxygen atoms that lead to labile oxygen electrons that participate in the practical capacity of cathodes.

A mirror-image polymerase—a version of African swine fever virus polymerase X made from D-amino acids—has now been chemically synthesized. This polymerase can catalyse template-directed L-DNA replication and transcription from L-DNA into L-RNA. These reactions represent two key steps in the central dogma of molecular biology—but demonstrated using the opposite chirality.

Effective light capture in photosynthetic organisms depends on the efficiency of all energy-transfer steps in the photosynthetic unit. Two-dimensional electronic spectroscopy has now been used on intact cells in situ to reveal and characterize the functional connectivity between individual complexes in the photosynthetic apparatus of green sulfur bacteria.

The formation of homochiral supramolecular networks at solution–solid interfaces typically relies on the soldier-and-sergeant approach, in which a small amount of chiral modifier defines the handedness of the network. Now, judicious choice of the sergeant, solvent, temperature and concentration has enabled chiral induction pathways to be controlled so that a homochiral surface of either handedness can be assembled from the same system.

A rod-shaped metal–organic framework can be converted into one-dimensional carbon nanorods through a catalyst-free thermal transformation in which the morphology of the material is preserved. The as-synthesized nanorods can be unravelled to form 2–6-layer graphene nanoribbons by ultrasonication in the presence of KOH, followed by thermal activation.

Dissipative self-assembly processes are energetically uphill and require the continuous consumption of energy. Now, by using ATP as a chemical fuel, the dissipative self-assembly of vesicles has been demonstrated. These transiently formed supramolecular assemblies are able to sustain a chemical reaction and it is shown that the yield depends on the lifetime of the vesicles.

Matic Lozinšek and Gary J. Schrobilgen consider krypton — namesake of Superman's home planet — its superoxidant compounds, and their roles in coaxing elements into their highest oxidation states.