Articles in 2017

The ability to merge the photophysical properties of semiconductor quantum dots with those of well-understood and inexpensive molecular chromophores is important for the development of various emerging photonic and optoelectronic technologies. Now, 1-pyrenecarboxylic acid-functionalized CdSe quantum dots have been shown to undergo thermally activated delayed photoluminescence and display tunable photophysical properties.

Enzymes that form a metabolic pathway in which the product of one enzyme is the substrate for the next have now been shown to associate through a process of sequential, directed chemotactic movement. The extent of enzyme migration is proportional to the exposure time to the substrate gradient.

Peptides derived from non-ribosomal peptide synthetases (NRPS) are an important class of pharmaceutically relevant drugs. However, no general rules for the modification of NRPS or the generation of artificial NRPS are known. Now, a new strategy for the modification of NRPS has been developed that uses defined exchange units that are fused at specific positions connecting the condensation and adenylation domains.

Catalytic transformations that incorporate carbonyl functional groups in arene C–H bonds have remained limited, despite being attractive synthetic steps. Now, the intermolecular carbonylative coupling of a broad range of simple arenes into ketones has been developed. The reaction occurs through the palladium-catalysed generation of high-energy aroyl triflate electrophiles.

The direct arylation of C–H bonds is an attractive synthetic step, but the reductive elimination of an organometallic catalyst carrying the desired C–H and aryl functionalities has remained challenging. Now, this step has been achieved by first oxidizing the iridium centre of the catalyst, which facilitates the arylation of arene C–H bonds of a range of substrates.

An arene-anchored uranium(III) complex that facilitates the electrocatalytic formation of H₂ from H₂O has now been shown to involve redox-cooperativity between the uranium centre and its covalently bound mesitylene ligand. The oxidative addition of H₂O to the uranium catalyst is a concerted two-electron reaction — atypical for f-block metals.

Selectively targeting native amino acids for late-stage protein modification is a significant challenge, but now it has been shown that photoredox catalysis can be used to specifically target protein C-termini toward decarboxylative-alkylation with Michael acceptors. This technology harnesses innate differences in side-chain oxidation potentials to select between the various functional groups typical among proteins in order to form a single modified product.

A centimetre-long string formed by the hierarchical self-assembly of a photoresponsive amphiphilic molecular motor — composed of 95 wt% of water — undergoes muscle-like contraction. Under irradiation, rotary motion at the molecular level is amplified through non-covalent interactions to sustain a fast macroscopic mechanical motion of large amplitude.

DNA–polymer conjugates are attractive materials that combine the programmability of nucleic acid assembly with polymer functionality. Now, through a DNA cube template, monodisperse polymer particles have been imprinted with several DNA strands in pre-designed orientations— each independently set and addressable. The resulting hybrid particles can further assemble into well-defined, non-centrosymmetric structures.

Photosynthesis uses sunlight to oxidize or reduce reaction centres multiple times and prepare them for multiple-electron-transfer reactions. Now, it has been shown that a molecular proxy for a multiple-electron-transfer electrocatalyst can be oxidized twice by dye molecules when both are anchored to a mesoporous TiO₂ thin film and excited with low-intensity visible light.

The anthraquinone and enediyne halves of the antitumor antibiotic dynemicin A were previously thought to be assembled by two separate polyketide synthases (PKS). Now, a single polyketide synthase has been proposed to be responsible for their production, and a working model for their biosynthesis from a common octaketide intermediate has been suggested.

Nonribosomal peptide synthetases (NRPSs) produce vital natural products but have proven recalcitrant to biosynthetic engineering. Now, a combination of yeast surface display and fluorescence-activated cell sorting (FACS) has been used to reprogram an L-Phe-incorporating module for β-Phe. The resulting module is highly selective and functions efficiently in NRPS pathways.

Water oxidation is key to the production of chemical fuels from electricity. Now, guided by theory, NiCoFeP oxyhydroxide catalysts have been developed that require an overpotential lower than that required by IrO₂. In situ soft X-ray absorption studies of neutral-pH NiCoFeP catalysts indicate formation of Ni⁴⁺, which is favourable for water oxidation.

Tau aggregation is associated with Alzheimer's disease and dozens of related dementias. Now atomic structures of the aggregation-prone segment VQIINK in repeat 2 of tau have been reported. Inhibitors designed using these structures block seeding by full-length tau better than inhibitors that target the VQIVYK aggregation segment in repeat 3.

Within natural product biosynthetic pathways, nature has evolved highly selective catalysts capable of complexity-generating reactions. Leveraging these tools, a suite of catalysts with complementary site- and stereoselectivity have been applied to the oxidative dearomatization of phenolic compounds, enabling one-pot transformations of phenols into various natural products.

Phosphorylation of (pre)biological molecules in water has been a long-sought goal in prebiotic chemistry. Now, it has been demonstrated that diamidophosphate phosphorylates nucleosides, amino acids and glycerol/fatty acids in aqueous medium, while simultaneously leading to higher-order structures such as oligonucleotides, peptides and liposomes in the same reaction mixture.

Cyclic amines bearing α-substituents are valuable building blocks for drug discovery and natural product synthesis. Introduction of α-substituents via site-selective replacement of C–H bonds is highly attractive but typically limited to protected amine substrates. Now, an operationally simple hydride-transfer-based approach enables the introduction of α-substituents on unprotected amines.

The rate constant of DNA hybridization varies over several orders of magnitude and is affected by temperature and DNA sequence. A machine-learning algorithm that is capable of accurately predicting hybridization rate constants has now been developed. Tests with this algorithm showed that over 90% of predictions were correct to within a factor of three.

Primer exchange reaction (PER) cascades have now been used to grow nascent single-stranded DNA with user-specified sequences following prescribed reaction pathways. PER synthesis occurs in a programmable, autonomous, in situ and environmentally responsive fashion, providing a platform for engineering molecular circuits and devices with a wide range of sensing, monitoring, recording, signal processing and actuation capabilities.

Electrochemical water oxidation in acidic media is a promising water-splitting technique, but typically requires noble metal catalysts. Now, two polyoxometalate salts based on earth-abundant metals have shown excellent catalytic performance for the oxygen evolution reaction. The barium salt of a cobalt-phosphotungstate polyanion outperformed the state-of-the-art IrO₂ catalyst at pHs lower than 1.