Articles in 2016

Proposed as the source of the light-dependent magnetic compass in migratory birds, the radical pair mechanism is thought to operate in flavoproteins in the retina. Now, it has been demonstrated that the primary magnetic field effect on flavin photoreactions can be chemically amplified by slow radical termination reactions under conditions of continuous photoexcitation.

The presence and linkage of unusual higher sugars in the ‘inner core’ of Gram-negative bacteria makes the core lipopolysacchride tetrasaccharide Hep₂Kdo₂ a tough target. Now, a 2+2 glycosylation strategy has facilitated the synthesis of this glycoconjugate. Synthesis of Hep₂Kdo₂ enabled an antibacterial vaccination strategy based on immunization with the glycoconjugate and the subsequent administration of an inhibitor that uncovers the corresponding epitope in pathogenic bacteria.

The Bergman cyclization is a fascinating rearrangement reaction with implications beyond organic chemistry. It has now been shown that a reversible Bergman cyclization reaction in a single molecule sitting on an ultrathin NaCl film can be triggered and directly imaged using atomic force microscopy. The interconverted diradical and diyne products are shown to have distinct chemical and physical properties.

Interpenetration of metal–organic frameworks (MOFs) is a common phenomenon, in which a structure consists of two or more identical, entangled sub-lattices. Now, MOFs with variable, fractional degrees of occupancy of one of two sub-lattices have been prepared. The extent of interpenetration can be controlled either during synthesis or by autocatenation, a framework rearrangement process.

Enantioselective aldol reactions with fluoroacetate would enable access to numerous fluorinated analogues of therapeutically important compounds but have been a long-standing unsolved challenge. Now, bioinspired fluoromalonic acid half thioesters (F-MAHTs) have been devised and allow for highly stereoselective reactions with aldehydes under mild organocatalytic conditions.

Preorganization of catalysts and substrates can lead to significant rate enhancement—an effect often observed in enzyme catalysis. Now, a self-assembled nanosphere equipped with 24 guanidinium binding sites is demonstrated to strongly bind sulfonate-containing gold catalysts. Base-triggered co-encapsulation of carboxylate containing substrates leads to pronounced gating effects and dramatically enhanced reaction rates.

Highly compressible crystalline materials typically rely on the high compressibility of their chemical bonds. Now, a family of LnFe(CN)₆ frameworks (Ln = Ho, Lu or Y) has been shown to exhibit pronounced volumetric and linear compressibilities through a spring-and-gear mechanism instead, in which a torsionally flexible LnN₆ unit twists reversibly under pressure.

Metal centres play an important role in the damage to biomolecules caused by radiation, but the respective microscopic mechanisms are unknown. Now it is shown that the absorption of X-rays by a metal ion leads to an intricate chain of ultrafast relaxation steps that results in the complete degradation of the metal's local environment.

Self-replicating molecules provide a simple molecular level system to study the processes occurring in speciation. Now it is shown that in a pool of interconverting macrocycles, constructed from two building blocks, two distinct sets of self-replicating molecules emerge, and that one is a descendant of the other.

Until recently, the three-body recombination reaction was widely regarded as the only reaction pathway to the production of molecular oxygen in Earth's prebiotic primitive atmosphere. Observation of a CO₂ photodissociation pathway altered this view, but now, using anion velocity imaging, a further source of molecular oxygen is revealed, formed via the dissociative electron attachment to CO₂.

DNA nanostructures are typically used as molecular scaffolds. Now, it has been shown that they can also act as reusable templates for ‘molecular printing’ of DNA strands onto gold nanoparticles. The products inherit the recognition elements of the parent template: number, orientation and sequence asymmetry of DNA strands. This converts isotropic nanoparticles into complex building blocks.

Single operation transformations that enantioselectively install a stereogenic centre while introducing a distal functional group are synthetically valuable but rare processes. Now, a copper-catalysed reductive relay hydroamination process that simultaneously creates a remote chiral centre is described. The resulting γ- and δ-chiral amines are important structural elements in many pharmaceutical agents and natural products.