Volume 8 Issue 8, August 2016

Ksenija Glusac takes us on a journey through some of the most important light-driven reactions upon which nature and chemists rely.

Self-sorting events in supramolecular assembly lead to complex systems that are attractive for the design of functional materials, but have remained difficult to understand and control. Now, the growth of self-sorted supramolecular nanofibres has been elucidated by direct imaging through real-time in situ confocal microscopy.

A quantitative understanding of the functional landscape of a biochemical circuit can reveal the design rules required to optimize the circuit. Now, a high-throughput droplet-based microfluidic platform has been developed which enables high-resolution mapping of bifurcation diagrams for two nonlinear DNA networks.

The slow kinetics of light-driven water oxidation on haematite is an important factor limiting the material's efficiency. Now, an intermediate of the water-splitting reaction has been identified offering hope that the full mechanism will soon be resolved.

Carbonyls and alkenes, two of the most common functional groups in organic chemistry, generally do not react with one another. Now, a simple Lewis acid has been shown to catalyse metathesis between alkenes and ketones in a new carbonyl olefination reaction.

Designing self-sorting events, and understanding their dynamics, in synthetic supramolecular assembly is a promising route towards complex, functional artificial systems. The formation of self-sorted supramolecular nanofibres has now been imaged in situ, in real time, by confocal laser microscopy. A stochastic, non-synchronous fibre formation through a cooperative mechanism was observed.

Biradical polycyclic hydrocarbons are promising materials for organic spintronic and photovoltaic applications. The efficient and scalable synthesis of a diindenoanthracene derivative that exhibits moderate biradical character, yet is remarkably stable towards oxygen and heat, is now reported. A thermally accessible magnetic triplet state was studied through variable temperature techniques.

Dynamic nonlinear biochemical circuits are functionally rich; however, this nonlinear nature also makes programming them delicate and painstaking. Now a droplet microfluidic platform reveals precisely the bifurcations of two canonical systems: a bistable switch and a predator–prey oscillator, exposing optimal regions and mechanistic insights that inform the design of these systems.

Organofluorine compounds are important to medical, agricultural and materials research. Now, small organic molecules may be used to catalyse reactions of fluorinated ketones with organoboron reagents, yielding tertiary homoallylic alcohols in high enantiomeric purity. Electrostatic interactions between a catalyst's ammonium group and fluoro-organic substrate are key to control of stereoselectivity.

Photoelectrochemical water oxidation with haematite is known to be associated with a build-up of holes at the electrode surface. Infrared spectra acquired during photoelectrochemical water oxidation have now allowed these holes to be identified as high-valent iron–oxo intermediate species involved in the water oxidation reaction.

The reactivity of the noble gases—a notoriously inert group—at high pressures is intriguing. Now, two xenon oxides with unusual stoichiometries, Xe₂O₅ and Xe₃O₂, have been synthesized above 78 GPa and predicted to be stable above 50 GPa, indicating that xenon is more reactive than previously thought.

Cyclic polymers are an area of significant interest, but understanding the potential of these macrocycles has been difficult because of challenges in their synthesis and characterization. It has now been shown that a tungsten catalyst featuring a tetraanionic pincer ligand can rapidly polymerize alkynes to form conjugated macrocycles in high yield.

Probing the chemistry of transuranic elements is notoriously challenging. Now, three neptunium(III) organometallic sandwich complexes have been prepared using a flexible macrocycle as ligand, and their molecular and electronic structures characterized, adding to our understanding of the behaviour of f-elements and suggesting that the lower oxidation state Np(II) may be chemically accessible.

Efficiently and selectively activating the C–H bonds within the light alkanes of natural gas is a challenge that must be overcome if we are to make the most of Earth's abundant reserves. An oxybromination method that functionalizes methane under mild conditions has now been developed and vanadium phosphate was identified as the best catalyst for this reaction.

Exceptional positional selectivity in aromatic substitution can now be achieved through a previously unappreciated phenomenon. Radicals with high electron affinity undergo radical aromatic substitution with nearly exclusive para selectivity by eliciting significant arene-to-radical charge transfer in the transition state of addition.

Stanislav Strekopytov relates the history of rare-earth element samarium, from its geological origins to its geochronological uses.