Research articles

Biological rotary motors can alter their mechanical function by changing the direction of rotary motion. Now, researchers have designed a synthetic light-driven rotary motor in which the direction of rotation can be reversed on command by changing the chirality of the molecular motor through base-induced epimerization.

An optical molecular imaging dye is described that is based on an interlocked squaraine rotaxane peroxide. These fluorescent and chemiluminescent dye molecules can be stored indefinitely at low temperature, but on warming to body temperature they undergo a unimolecular reaction, emitting near-infrared light that can pass through a living mouse.

A small-molecule-affinity tag has been designed to mediate the selective isolation of G-quadruplex nucleic acids in a structure-dependant manner. This concept has been applied to the pull-down of G-quadruplex-containing fragments from human cells, and the methodology holds promise for the elucidation of their putative biological functions.

Crystallographically studying chemical reactions is difficult because the intermediates are rarely stable enough to be crystallized. Now, protein crystals have been used to trap four reaction intermediates in an aromatic dihydroxylation, showing that an iron peroxo complex is observed.

Supramolecular gels show promise in diverse areas, including healthcare and energy technologies, owing to tunable properties that arise directly from the organization of their building blocks. Researchers have now been able to control this behaviour by combining enzymatic catalysis with molecular self-assembly. Although it seems counter-intuitive, gels that assembled faster showed fewer defects.

Supramolecular gels based on small-molecule gelators have been shown to be effective media for the growth of organic crystals, including pharmaceutical compounds. Moreover, the gel-to-sol transition can be triggered by molecular recognition with anions, thereby enabling facile recovery of the crystals.

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 accessibility of catalytically active sites in enzymes is maintained by the surrounding amino acid residues, but in synthetic metal clusters, these sites are typically blocked by the organic groups used to coat them. It has now been shown that the accessibility of gold clusters bound by calixarenes can be controlled by tuning the relative sizes of the metal cores and the ligands.

C–H activation has usually been achieved by transition metal-mediated pathways. Here, a cross-coupling between aryl halides and common arenes mediated by 1,10-phenanthroline as catalyst, in the presence of potassium tert-butoxide as base is described. Such reactions open a new window for achieving C–H activation without the need for transition metal catalysts.

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.

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.

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.

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.

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 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.

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.

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 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.

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.