Volume 8 Issue 9, September 2016

Chemists have long been fascinated by electron delocalization, from both a fundamental and applied perspective. Macrocyclic oligomers containing fused ferrocenes provide a new structural framework — containing strongly interacting metal centres — that is capable of supporting substantial charge delocalization.

Density functional theory calculations can be carried out with different levels of accuracy, forming a hierarchy that is often represented by the rungs of a ladder. Now a new method has been developed that significantly improves the accuracy of the 'third rung' when calculating the properties of diversely bonded systems.

Introducing C–F bonds into organic molecules is a challenging task, particularly through C–H activation methods. Now, a uranium-based photocatalyst turns traditional selectivity rules on their heads and fluorinates unfunctionalized alkane Csp³–H bonds, even in the presence of C–H bonds that are typically more reactive.

An artificial esterase with no known natural structural analogues has been formed via the homo-heptameric self-assembly of a designed peptide. This esterase represents the first report of a functional catalytic triad rationally engineered into a de novo protein framework.

Cyclic molecules often exhibit unusual properties; consider for example the resonance stabilization energy of benzene or the strong cation binding of crown ethers. Now, a family of rings comprising varying numbers of directly linked ferrocenes has been prepared. These compounds are highly symmetric in solution and undergo rapid ‘oxidation-state isomerism’ when charged.

Whether a molecule or material can exist, and with what structures and energies, is of critical importance. For demanding calculations the efficiency of density functional theory makes it the only practical electronic structure theory available to help answer these questions. Now, an efficient density functional is shown to have unprecedented accuracy for a diverse set of bonded systems.

Functional catalytic triads have been designed into a hyperstable heptameric α-helical barrel protein. Twenty-one mutations were introduced to form seven Cys-His-Glu catalytic triads. The resulting protein hydrolyses p-nitrophenyl acetate with activities matching the most-efficient redesigned hydrolases based on natural protein scaffolds. This is the first example of a functional catalytic triad being engineered into a fully de novo protein.

A primary objective in solar energy conversion is to achieve long-lived light-driven redox separation. Now a modular self-assembly strategy has been developed to construct molecular p/n junctions surface-bound to transparent conducting ITO nanoparticle electrodes. Both photoanode and photocathode assemblies achieved remarkably long-lived redox separation lifetimes without making use of traditional wide-bandgap semiconductors.

While important for solar energy conversion, it is unclear whether electron transfer at molecular–semiconductor interfaces is influenced only by the distance over which the injected electron tunnels and whether specific through-bond pathways are active. Now, a pathway for electron transfer has been identified through comparative analysis of compounds with phenyl- or xylyl-thiophene bridges.

Control of motion at the molecular level is an integral requirement for the development of future nanoscale machinery. Now, governed by the fundamental reactivity principles of organometallic chemistry, a biaryl rotor is shown to exhibit 360° unidirectional rotary motion driven by the conversion of two simple fuels.

A broadly applicable strategy that can control the self-assembly of nanoparticles into a predefined structure has been reported. Integrating nanoparticles with DNA constructs creates individual modules that can be assembled into complex planar architectures. The approach combines nanoparticles with the selectivity and directionality of bonds provided by DNA.

A temperature-dependent kinetic study of ground-state proton transfer in the green fluorescent protein highlights the role of ‘deep tunnelling’ in proton wires. A potential mechanism for directional proton transport is proposed, where high-pK_a amino acid residues act as ‘tunnel diodes’ and as stabilizing elements within protein water wires.

Cell-sized asymmetric giant lipid vesicles containing a very small amount of organic solvent have now been formed via inhomogeneous break-up of a lipid microtube that was generated by applying a jet flow to an asymmetric planar lipid bilayer. The asymmetric giant vesicles were used to investigate the dynamic responses of lipid molecules and the effect of asymmetry on biochemical reactions.

Two neutral compounds containing a zero-valent s-block metal, beryllium, have now been isolated and fully characterized. Structural characterization, supported by calculations, show that these brightly coloured complexes adopt a closed-shell singlet configuration with a Be(0) metal centre and an unusually strong three-centre two-electron π-bond across the C–Be–C unit.

Alpha decay into flerovium? It must be Lv, says Kat Day, as she tells us how little we know about element 116.