Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Understanding the interplay between singlet fission and exciton transport is important if singlet-fission materials are to be used for solar cell applications. Now, a cooperative singlet–triplet transport mechanism has been revealed through ultrafast transient absorption microscopy.
Protein PEGylation is routinely used to produce molecules with improved pharmacokinetic properties. However, despite their importance, the structure of PEGylated proteins has remained elusive. Now, the first crystal structure of a model β-sheet protein modified with a single PEG chain has been reported. NMR spectroscopy data indicates that the protein and PEG behave as independent domains.
Analysis of the structure of the highly complex yet racemic secondary metabolite epicolactone suggests that it may arise biosynthetically from a cascade similar to that which produces purpurogallin. This led to a synthesis of epicolactone in only eight steps using an intricate reaction cascade.
Regioselective epoxide opening of an enantiopure epoxy–alkyne results in the stereospecific introduction of functional side-chains into growing macromolecules. This process—in combination with 'click' chemistry and orthogonal deprotection of terminal alkynes—underpins an iterative exponential growth methodology that enables the efficient synthesis of >6-kDa stereo- and sequence-controlled polymers.
Catalysis with N-heterocyclic carbenes produces diverse outcomes depending on which of the many possible reaction mechanisms dominates. Control of this reactivity within a single reaction type has rarely been demonstrated. Now, starting from identical substrates, a switchable catalytic activation is shown to afford different products with high regio- and stereoselectivity.
The question of how divalent metal ions direct the folding of ribozymes is a major unsolved problem. A computational model has now been used to reveal the molecular mechanism by which Mg2+ drives the Azoarcus ribozyme into a catalytically functional state. Simulations also show that although Ca2+ drives folding it leaves the active site unstable.
Cyclohexa-2,5-dien-1-yl groups bound to silicon act as masked Si–H bonds that can be released by the action of tris(pentafluorophenyl)borane (B(C6F5)3). In this way, hazardous SiH4 is unleashed from appropriately substituted precursors and engages in alkene hydrosilylation promoted by the same boron catalyst. The overall process is a transfer hydrosilylation of alkenes with monosilane.
The late-stage functionalization of unactivated C(sp3)−H bonds could be useful for the rapid development of structure–activity relationships, but highly target-specific conditions make it challenging. Now, a strategy for the preparation of a variety of β-functionalized alcohol derivatives through a site-selective C−H sulfonyloxylation and subsequent SN2 reactions is described.
A cascade reaction network has been created that can function in a manner that is superficially similar to the most basic steps of the vertebrate adaptive immune response. This reaction network uses DNA and enzymes as simple artificial analogues of the components of the acquired immune system.
The ultrafast and mode-specific infrared excitation of several donor–bridge–acceptor (DBA) assemblies in solution has been shown to modulate their light-induced electron transfer properties. New insights are afforded into the role of vibrational processes immediately following light absorption in charge-transfer molecules and a recipe for efficient ‘vibrational control’ of electron transfer is proposed.
Directing groups in a substrate are frequently used to direct the regioselectivity of C–H activation reactions. Now it has been shown that regioselectivity can be directed by a ligand, which binds to both the catalysing metal centre and a distal hydrogen-bond acceptor in the substrate. This secondary interaction places the metal in close proximity to the reacting C–H bond.
Perovskite materials show great promise for solar cell devices, owing in particular to their high power conversion efficiency. Now, the addition of butylphosphonic acid 4-ammonium cations during a one-step process has been shown to improve both the efficiency and moisture stability of perovskite photovoltaics, through the formation of hydrogen-bonding crosslinks between neighbouring grains.
Ring-opening metathesis polymerization (ROMP) offers good control over dispersity, but the requirement of one initiator per chain can be expensive and problematic for purification. Now, a reversible cyclohexenyl-containing chain-transfer agent is described, thus allowing a catalytic living ROMP process to produce narrow dispersity polymers and block copolymers.
Graphene possesses numerous interesting properties yet the preparation of pristine sheets has remained challenging, hindering practical applications. Now, a rapid, highly efficient step has been devised that uses microwave irradiation in oligomeric ionic liquids to exfoliate graphite into pristine ‘single layer’ sheets (<1 nm thick). A concentrated dispersion of the resulting material behaves as a physical gel.
Forged by evolution, the natural enzymatic pathways to aldose carbohydrates are complex. Now, a biocatalytic stereoselective one-pot assembly of these carbohydrates from formaldehyde and glycolaldehyde using engineered D-fructose-6-phosphate aldolase (FSA) variants has been developed that circumvents this complexity.
Formaldehyde is universally employed in the fixation of tissue specimens, where it forms adducts with biomolecules, but this hinders the analysis of nucleic acids in the specimen. Bifunctional organocatalysts that speed the reversal of formaldehyde adducts of RNA and DNA are now reported, and show promise for general use in clinical specimens.
Cytochrome P450 (P450) and chloroperoxidase (CPO) are both thiolate-ligated haem proteins that form a ferryl radical species called compound I. P450-I is, however, significantly more reactive than CPO-I. Variable-temperature Mössbauer and X-ray absorption measurements have now shown that increased electron donation from the axial thiolate ligand in P450-I may explain its greater propensity for C–H bond activation.
The complexity and diversity of natural product structures make them an ideal starting point for the creation of chemical libraries. Now it is shown that a semi-synthetic process can combine heterologous expression of a multipotent biosynthetic intermediate with multiple non-enzymatic steps to produce libraries of pseudo-natural products.
Fe(II) complexes display transitions between spin states that can be triggered externally. Now the light-induced ΔS = 2 transition upon excitation of the metal-to-ligand charge-transfer states of Fe(II)-polypyridine complexes has been investigated at high time-resolution in the visible and the ultraviolet range. It has been shown to occur in less than 50 fs — that is, on a sub-vibrational timescale.
Controlling the self-assembly of nanoparticles using light has been demonstrated in many systems where the particle surfaces are functionalized with photoswitchable ligands. Now, it has been shown that the light-controlled self-assembly of non-photoresponsive nanoparticles can be achieved in a quantitative and reversible fashion by placing them in a photoresponsive medium.
