Optical activity can be positive or negative depending on whether the electric and magnetic dipole transition moments point into the same or opposite halves of a sphere centered on the molecule. A new technique takes a different route: Radiation emitted by molecules of opposite chirality associated with a loop of three dipole-allowed transitions between rotational states is exactly out of phase, thus providing a direct signal of molecular chirality.

Two birds with one stone: Recent advances in activating two reactants simultaneously using homogeneous visible-light photoredox catalysis have been described. The conceptually new catalytic mode will aid in the design of some green and sustainable reactions.

Remote control: The title reaction is effective for the sulfonation and alkylation of arenes bearing directing groups. Initial ortho metalation of the substrate forms an intermediate which does not evolve towards functionalization at the CM bond. Instead, the ruthenium catalyst acts as a strong electron-donating group, thus directing a remote electrophilic attack.

Back to square one: Two recent studies prove that reactive oxygen species (ROS) are not responsible for bacterial cell death after treatment with antibiotics. The ROS concept cannot be generalized to explain all processes resulting in cell death. The search for the mechanism of action of bacterial antibiotics must thus return to the beginning.

Quest for transparency: Detailed optical imaging of complex biological entities remains an unmet goal mainly because of the light scattering of biological tissue. A new approach to tissue clearing termed CLARITY is getting us closer to an anatomical view of thick tissues and entire organs with cellular resolution.

Tip-enhanced Raman spectroscopy combines scanning probe techniques with Raman spectroscopy. Latest developments permit the chemical mapping of individual adsorbed molecules by monitoring molecular vibrations with sub-nanometer resolution. Increased efficiency and reduced photodegradation make this method suitable for studies of adsorbed organic and biomolecules in surface science, catalysis, biochemistry, and related fields.

Inside insight: Pactamycin has long been recognized as a potent bioactive compound and a formidable target for chemical total synthesis. Recently, Johnson and co-workers published a 15-step enantioselective synthesis of pactamycin that capitalized on the recognition of latent symmetry in the core structure.

Chelate me if you can: Over the last decade, strategies for the functionalization of both CH and CH bonds have witnessed an increasing use of a simple, yet powerful directing group, 8-aminoquinoline (in blue). This auxiliary is very efficient in a wide range of metal-mediated reactions, and can be readily removed to afford the desired carboxylic acids or corresponding derivatives.

Enoyl intermediates are normally obtained through β-elimination of β-hydroxy carbonyl compounds. The OH group is eliminated either directly or is first activated through phosphorylation. Alternative strategies have now been identified: Glutamination or acetylation of a β-hydroxycarbonyl compound followed by β-elimination of an ester was proven to be a key step in the biosynthesis of class I lantipeptide and tetronate antibiotics.

Subtle differences: Two recent crystal structures have provided the first insight into nitrate/nitrite exchangers (example shown with bound nitrite), which are crucial to bacterial metabolism. A direct comparison of the structures reveals how the proteins can distinguish between their highly similar substrates and translate this into a conformational change to translocate ions across the membrane.

Working together: The presence of a remote directing group on terminal 1,1-diaryl and 1,1-dialkyl alkenes led to high and unprecedented enantioselectivity in iridium-catalyzed asymmetric hydrogenation (see scheme). This strategy offers efficient synthetic pathways towards valuable enantiomerically enriched 1,1-diaryl and 1,1-dialkyl alkanes. Moreover, the directing group can be further functionalized.

Aiming high: In the pursuit of new high-nitrogen structures, researchers have synthesized some interesting compounds with highly catenated chains of nitrogen atoms through a strategy of oxidative azo coupling of NNH₂ moieties. This strategy opens opportunities for developing longer nitrogen chains in the field of high-nitrogen compounds.

N-H₂eterocycles: Significant advances have been made in the development of the enantioselective partial or full hydrogenation of substituted isoquinolines and isoquinolinium and pyridinium salts. The products are valuable chiral 1,2,3,4-tetrahydroisoquinolines and piperidines (see scheme).

No matter how you slice it: New insight into nanostructured materials is provided by a novel imaging technique, which reproduces the real three-dimensional (3D) fine structure of nanomaterials at the atomic level from two-dimensional (2D) projections (see scheme).

The thiyl radical of cysteine 272 (C272) in the C-P lyase adds to 5-phosphoribose-1-methylphosphonate to give a covalently bound thiophosphonate radical. Reaction with glycine 32 (G32) of the enzyme yields methane, a glycyl radical, and thiophosphate (see scheme). Intramolecular attack of the 2-OH group leads to 5-phosphoribose-1,2-cyclic-phosphate, whereas the glycyl radical oxidizes the liberated SH group back to the thiyl radical.

A new generation of three-dimensional carbon nanostructures is evolving. These flexible carbon systems based on carbon nanotubes and nanofibers and graphene sheets are capable of substantial shape deformation and thus have exciting applications in flexible electronics, sensors, and complex mechanical structures.

A remarkable approach to the production of large mesoporous anatase single crystals was reported recently by Snaith et al. These crystals display two properties—high surface area and high electron mobility—that fundamentally affect the performance of any TiO₂-based photoelectrochemical device, such as Grätzel-type dye-sensitized solar cells.

Are aliphatic alkynes truly bioorthogonal? In an attempt to prepare clickable ubiquitin derivatives bearing a C-terminal propargyl amide, two groups have now independently discovered propargylamides to be irreversible inhibitors of cysteine proteases. The unexpected findings demonstrate the unexpected reactivity of alkynes in protein-templated reactions and introduce a novel class of activity-based protein probes.

Minerals are the benchmark of hard and brittle materials. Self-assembled calcitic spicules were recently obtained utilizing a protein from silica biomineralization, silicatein-α. The synthetic spicules show remarkable material properties including extreme flexibility. Breakthroughs in bio-inspired materials science are highlighted. Will it be possible to obtain similar composites with truly artificial organic constituents?

Nanochannels for power generation: The confinement of fluid motion in a single boron nitride nanotube can provide an efficient means of power harvesting owing to the osmotically driven streaming current under a salt concentration difference (see picture). Devices based on this principle may open a new avenue in the exploration for new sources of renewable energy.