Volume 5 Issue 4, April 2013

Bruce Gibb ponders what the future of chemistry research might look like if we take a more data-driven approach.

Strategies for making sequence-controlled polymers in the laboratory are really quite primitive in comparison with those used in nature. By combining concepts from natural systems and synthetic polymer chemistry, it has now been shown that DNA codes can be translated into non-nucleic-acid polymers with defined sequences.

The study of the reaction of a ground-state O atom with H₂ has previously proved difficult because of its high activation barrier. Now, new experiments have revealed unexpected OH product states; but perhaps there is a simple explanation?

Hydrogen–oxygen alkaline fuel cells are promising devices for the 'hydrogen economy' but their oxidation of hydrogen fuel is slow compared with that of acidic fuel cells. More efficient electrocatalysts have now been prepared in which the adsorption of hydroxyl groups onto the electrode surface is controlled through suitable promoters.

Combined spectroscopic measurements and theoretical calculations bring to light an ultrafast excited-state deactivation process in peptides that may contribute to the ultraviolet photostability of proteins.

During photosynthesis, the oxygen-evolving complex oxidizes water to produce molecular oxygen. Now, a possible role for the calcium ion in this complex has been proposed based on the electrochemical properties of a series of synthetic heterometallic clusters.

A small molecule that mimics the sequence-specific peptide synthesis of nature's ribosomes paves the way for more elaborate artificial molecular synthesizers.

Two-dimensional materials have recently garnered much interest in the scientific and technology communities. This Review describes how ultrathin transition metal dichalcogenides combine tunable structure and electronic properties, achieved through altering their composition, with versatile chemistry. This makes them attractive in various fields, for example as lithium-ion battery electrodes and electrocatalysts for the hydrogen evolution reaction.

A crystalline porous organic cage molecule is shown to have exceptional specificity for separating different structural isomers of C9 aromatics. Uniquely, this solid-state specificity is preconfigured in the discrete molecular building block, which shows an analogous specificity in solution. Both solution and solid-state behaviours can be understood by molecular dynamics simulations.

An enzyme-free system that translates DNA into sequence-defined non-nucleic acid polymers including polyethylene glycol, α-(D)-peptides and β-peptides is described. Sequence-defined polymers with molecular weights of 26 kDa containing 16 consecutively coupled building blocks and 90 densely functionalized β-amino acids were translated from DNA templates using this strategy.

The presence of Ca²⁺ is essential for the activity of the oxygen-evolving complex (OEC) of Photosystem II, although its exact role is still unclear. Now, electrochemical measurements of structural mimics of the OEC — based on mixed-metal trimanganese dioxido complexes — reveal a correlation between the Lewis acidity of the redox-inactive metal and the reduction potential of the complex.

Hydrogen is an attractive alternative to fossil fuels, but the slow rate of the hydrogen oxidation reaction in alkaline fuel cells hinders their development. It is now proposed that bifunctional materials can be devised to offer the optimal balance between hydrogen and hydroxyl adsorption, thus significantly reducing the amount of precious metal on the anode.

The heat shock protein Hsp90 is a potential target for cancer and neurodegeneration drugs. Here, the introduction of a substituent into the 19-position of the naturally occurring inhibitor geldanamycin by chemical synthesis is shown to ameliorate toxicity, and also cause a favourable conformational switch that is required for protein binding.

The reaction O(³P) + H₂ → OH(X²Π) + H has, until now, eluded detailed experimental investigation. Now, a laser-induced fluorescence study of the deuterated analogue has revealed product-state distributions that defy the current descriptions of non-Born–Oppenheimer mixing on coupled potential energy surfaces, issuing new challenges to theory.

Although it is achieved routinely by nitrogenases, the conversion of molecular dinitrogen into ammonia under ambient conditions is proving difficult with synthetic systems. A thiolate-bridged diiron complex has now been developed that produces ammonia from coordinated N₂H₂ through a sequence of reduction and protonation reactions that may well mimic the biological nitrogen fixation.

The photochemical-induced dimerization of bromine-terminated oligo(ethynylene)s in the solid state is shown to give 1,2-dibromoeneynes on a preparative scale. This single-crystal-to-single-crystal transformation proceeds through a multistep reaction that involves the making and breaking of several bonds in addition to large atom displacements. The reaction represents an atom-efficient and catalyst-free pathway towards functional carbon-rich molecular scaffolds.

A strategy to endow vinyl polymers with pseudo-crystalline order has been devised that relies on host–guest cross-polymerization, through functionalization of the channels of a porous coordination polymer with divinyl moieties. Polymerization of vinyl monomers within the channels is accompanied with lateral crosslinking, which ensures the polymer chains remain highly ordered after removal of the host.

A ruthenium complex bearing a chemically and redox-non-innocent tetradentate diolefin diazadiene ligand is shown to be an efficient homogeneous catalyst for the conversion of a 1:1 mixture of methanol and water to hydrogen and carbon dioxide. Development of this process is an important step in the production of hydrogen for use as a fuel from biomass.

Eric J. Schelter ponders on cerium's rather puzzling redox reactivity, and the varied practical applications that have emerged from it.