Volume 7 Issue 6, June 2015

The first synthesis of the all-cis isomer of 1,2,3,4,5,6-hexafluorocyclohexane, a molecule with one hydrocarbon face and one fluorocarbon face, is a tour de force of organofluorine chemistry and opens up new possibilities for molecular design.

Bulk SiO₂ is widespread in nature, and silicon oxide clusters are important to a variety of applications, yet molecular silicon oxides have remained elusive. Two molecular compounds featuring silicon oxide moieties, Si₂O₃ and Si₂O₄, have now been isolated by oxidation of a carbene-stabilized disilicon precursor.

Incorporating mechanically interlocked molecular shuttles within a metal–organic framework that has enough free space in the crystal lattice to permit volume-conserving translational motion sets the stage for defect-free molecular-electronic device fabrication and more.

Supramolecular polymerizations typically proceed through stepwise intermolecular mechanisms, concomitant with many side reactions to yield aggregates of unpredictable size, shape and mass. Now, a chain-growth strategy is shown to allow assembly of molecules into supramolecular chain structures endowed with precisely controlled characteristics.

Computations of the energetics and mechanism of the Morita–Baylis–Hillman reaction are “not even wrong” when compared with experiments. While computational abstinence may be the purest way to calculate challenging reaction mechanisms, taking prophylactic measures to avoid regrettable outcomes may be more realistic.

One-pot tandem reactions are attractive for both waste and time reduction, but can also enable transformations otherwise unobtainable in single-step processes. This Perspective covers recent advances in orthogonal tandem catalysis, while introducing the concept of thermodynamically leveraging multiple catalytic systems together to perform challenging transformations.

The highest-energy stereoisomer of 1,2,3,4,5,6-hexafluorocyclohexane, with all the fluorines ‘up’, has been prepared in a 12-step protocol. The molecule adopts a chair conformation with three triaxial C–F bonds on one face generating a polarized ring. In the solid state the molecules pack in an orientation consistent with electrostatic ordering.

Two semi-synthetic processes for the production of the antimalarial natural product artemisinin have been developed by applying the principles of green chemistry. Solvent manipulation allows catalyst recycling and reduction of waste, ultimately leading to a purification-free process with lower environmental and economic costs; a potential contribution to the world-wide fight against malaria.

Better understanding of the chemistry of rechargeable metal–oxygen batteries is needed to fulfil their potential. It is now shown that proton phase-transfer catalysts drive Na–O₂ batteries, transporting superoxide between the electrode surface and the electrolyte as HO₂. The chemistry uncovered gives rise to the system's high reversible capacity.

During the early stages of life on Earth sophisticated RNA catalysts must have formed from simple precursors. Here it is shown that freeze–thaw cycles can drive the assembly of complex RNA polymerase ribozymes from networks of short RNA oligonucleotides through an unanticipated RNA chaperone effect.

Molecular SiO₂ and other simple silicon oxides have remained elusive despite the importance of silicon dioxide materials in advanced electronic devices. Clusters Si₂O₃ and Si₂O₄ have now been experimentally realized by direct oxidation of a carbene-stabilized disilicon using N₂O and O₂, respectively.

The piston-like, translational motion of a molecular shuttle — a process that is fundamental to many mechanically interlocked molecular switches and machines — has now been demonstrated to occur inside the highly organized and dense structure (containing approximately 10²¹ shuttles per cm³) of a metal–organic framework material.

Equilibrium adsorption of non-racemic mixtures of enantiomers onto an achiral surface is shown to lead to enantioenrichment by formation of homochiral clusters. Such auto-amplification must influence enantioselective processes such as heterogeneous catalysis, adsorption-based separations, and perhaps the processes that lead to the homochirality of life on Earth.

Metallacycles made up of six copper ions and six cyclotriguaiacylene-based ligands form a unique topological entanglement in the solid state. Individual metallacycles are interwoven into an infinite 2D chainmail network where each one forms multiple Borromean-ring-like associations with its neighbours. Crystals of the complex grow in an unusual tubular morphology.

Brett F. Thornton and Shawn C. Burdette consider holmium's hotly contested discovery and later obscurity.