Volume 7 Issue 4, April 2015

The spontaneous syntheses of some of life's building blocks from simple precursors have previously been demonstrated in isolation. Now it has been shown that they might all emerge from just one set of ingredients.

Building on our understanding of the chemical bond, advances in synthetic chemistry, and large-scale computation, materials design has now become a reality. From a pool of 400 unknown compositions, 15 new compounds have been realized that adopt the predicted structures and properties.

A supramolecular polymer comprising stacked artificial chromophores to which zinc(II) complexes are appended is able to respond to enzymatic hydrolysis in aqueous solution. The assembly of molecules can twist reversibly and quickly in response to changes in the type of adenosine phosphate present.

Supramolecular assembly has been used to design and create new proteins capable of performing biomimetic functions in complex environments such as membranes and inside living cells.

Identifying the contribution of different surface sites to the overall kinetics of molecular desorption from solid surfaces is difficult even when using single crystals. A new technique that combines molecular beams with UV−UV double resonance spectroscopy resolves this problem for the case of carbon monoxide on Pt(111).

Ferroelectric materials hold much promise for the development of devices such as nonvolatile memories, sensors and nonlinear optic materials. This Review describes the molecular features required to devise organic molecular ferroelectrics, and presents the supramolecular chemistry strategies available for controlling molecular organization and dynamics across different length scales.

DNA nanotubes are attractive building blocks for the assembly of complex arrays. An efficient solid-state synthesis for producing surface-grafted, robust nanotubes has now been devised. Rungs are incorporated in a stepwise manner so that each one is addressable. Using fluorescent tags, the nanotube growth was visualized at the single-molecule level.

A minimal cell — one that has all the minimum requirements for life — is still a complex entity comprising informational, compartment-forming and metabolic subsystems. Here it is shown that, contrary to previous assumptions, a common prebiotically plausible chemistry can give rise to building blocks for all the subsystems.

A method to predict the stability, structure and properties of as-yet-unreported materials has been devised. For 18-valence electron ABX materials, 15 such ‘missing’ compounds identified to be thermodynamically stable were successfully synthesized, and showed crystal structures and properties in good agreement with the predicted ones.

Biopolymers adopt functional tertiary structures through folding and multiplex formation. Synthetic molecules with protein-like dimensions — monodisperse cyclic porphyrin polymers with diameters of 13–21 nm — have now been shown to exhibit biomimetic self-organization by forming nested structures on a gold surface. These assemblies are formed both under vacuum and during deposition from solution.

Externally applied mechanical forces can steer molecules along reaction paths that are otherwise inaccessible. Single-molecule force spectroscopy has now been used to quantify the force required to induce symmetry-forbidden reactivity in three different reactions and compare their behaviour to that of the symmetry-allowed analogues.

Photoelectrochemical water-splitting produces hydrogen at the cathode and oxygen at the anode. The anode reaction is, however, kinetically unfavourable. Now, reduction of water at the cathode has been combined with oxidation of 5-hydroxymethylfurfural at the anode resulting in a photoelectrochemical cell that produces fuel and a useful platform chemical.

Designing synthetic molecular receptors that can differentiate between specific monosaccharide guests is very challenging. Now, a helically folded oligoamide that selectively encapsulates fructose has been designed using an iterative approach that exploits the modular structure of folded synthetic oligomer sequences, in conjunction with molecular modelling and structural characterization.

Two metallacages containing Pt(II) phosphine centres bridged by organic donors are shown to display dynamic emission behaviour across a range of concentrations. At low concentrations, the individual cages emit. At high concentrations, or on introduction of additional solvents, aggregation occurs that manifests in colour-tunable fluorescence and white-light emission in THF.

Long-lived molecular collision complexes — or ‘resonances’ — are difficult to identify experimentally. Now crossed-beam experiments and quantum calculations are reported for rotationally inelastic CO−He collisions at energies corresponding to temperatures as low as 4 K. Quantum dynamical resonances that are predicted by theory were detected and fully characterized.

Interlocked molecules represent some of the most challenging synthetic targets in terms of non-natural products. It has now been demonstrated how a cyclic [3]catenane composed of three mutually interpenetrating rings can be prepared in two stages using a selective imine exchange reaction on a self-assembled triangular precursor.

Eric Ansoborlo and Richard Wayne Leggett discuss the chemical and radiological characteristics that make caesium a captivating element but also a troublesome contaminant.