Volume 2 Issue 11, November 2010

The dynamics of a complex chemical reaction that occurs through a well-defined intermediate have been followed at the single-molecule level using a 'nanoreactor' set-up, revealing a primary hydrogen isotope effect that is invisible to ensemble experiments.

Hydration is known to affect molecular-recognition processes, such as those between proteins and ligands. Now, theoretical simulations provide thermodynamic insight into cavity–ligand binding, revealing how it is predominantly driven by the behaviour of the few surrounding water molecules.

Compression of the active sites of enzymes has been linked to the bulk of amino acid side chains, but now experiments highlight that the harder we look, the more curious the relationship between protein structure and function becomes.

Computational studies have been used to accurately model the properties of a metal–organic framework. The material, subsequently synthesized, lived up to the predicted high surface area and sorption ability.

Chemists have now prepared the longest known stable subunit of the elusive all-carbon polymer — carbyne. Their results suggest that carbyne itself would have a polyyne-like rather than a cumulene structure.

When it comes to porosity, the materials that spring to mind are typically one-, two- or three-dimensional extended networks. In this Perspective, discrete organic molecules are discussed that form porous solids — either owing to hollow molecular structures or simply through inefficient packing — with different properties from those of extended networks.

When anchored inside a protein pore, the bond-making and bond-breaking events of a single reacting molecule can be detected by alterations in current flow. This approach is used to detect a hydrogen–deuterium kinetic isotope effect. The single-molecule measurements provide information not available from experiments on an ensemble system.

The impact of photo-damage on natural photosynthetic systems is lessened through their autonomous self-repair, and now a synthetic photoelectrochemical complex that mimics this behaviour has been developed. It is shown that a series of regeneration steps, driven by chemical signalling, increases the photo-conversion efficiency of the system and extends its lifetime indefinitely.

A new class of stable, isolable N-silyl oxyketene imines derived from protected cyanohydrins is introduced. Utilization of these nucleophiles in Lewis-base-catalysed aldol additions allows access to either cross-benzoin or glycolate aldol-type products in good yields and exceptional selectivities by simply altering the conditions of the reaction.

Metal ions and organic linkers have been assembled into a wide variety of metal–organic frameworks, but tailoring the properties of these materials for specific applications by designing them from first principles has proved difficult. Now, a highly porous MOF that was first identified through computational studies has been prepared and found to exhibit excellent gas-uptake.

The formation of simple prebiotic organic compounds on early Earth is thought to be an important step in the origin of life. Molecular dynamics simulations of the conditions within cometary ice during planetary impact suggest a possible mechanism for the formation of glycine, an amino acid.

Stable fullerenes often follow the isolated pentagon rule, but there are increasing examples of compounds that do not. Now, a maximum pentagon separation rule is proposed, which predicts that the most stable cages are those with pentagons having the largest separation.

Application of supramolecular chemistry in living systems is challenging because of the inherent chemical complexity of cellular environments. Now, the use of a carefully designed host–guest system featuring diaminohexane-terminated gold nanoparticles and complementary cucurbit[7]uril macrocycles has been shown to provide triggered activation of a therapeutic system in living cells.

The structure of the carbon allotrope ‘carbyne’ is based on a framework of sp-hybridized carbon. To model its properties, a series of conjugated polyynes — the longest of which contains 44 contiguous acetylenic carbons — have been synthesized and their spectroscopic properties investigated.

Processes that convert racemic chiral compounds into enantioenriched chiral products are highly sought after. Here, in a copper-catalysed borylation reaction one enantiomer of a cyclic allylic ether reacts with anti-stereoselectivity and the other reacts with syn-stereoselectivity. The starting material is not easily racemized and this new process is dubbed an enantioconvergent reaction.

Although ultrasonic vibrations are known to be capable of aligning macromolecules in solution, the question of whether audible sound — which has much lower frequencies — can have such an effect is somewhat controversial. Now, however, it has been shown that supramolecular nanofibres can be preferentially aligned parallel to the propagation direction of audible sound.

The design of receptors for the selective capture of F⁻ is important because of the potential toxicity of this anion. Now, a telluronium borane has been shown to form a very stable fluoride chelate complex. The stability of the complex can be correlated to the Lewis acidity of the telluronium centre.

Nature frequently shows exquisite control over reactions both of water and in water. Here, the enantioselective conjugate addition of water to an enone — a reaction that has no equivalent in conventional homogeneous catalysis — is catalysed by a copper complex of an achiral ligand that is non-covalently bound to DNA.

Jim Ibers talks about neptunium, an element that has remained largely unnoticed despite the flurry of activity devoted to its neighbours in the periodic table, uranium and plutonium.