Volume 4 Issue 1, January 2012

The most complex non-DNA synthetic molecular knot so far has been made in a single step by combining a number of reversible chemical interactions, including metal-directed self-assembly, anion templation and imine bond formation.

Traditional wisdom suggests that excited electrons will move towards positively charged parts of a molecule. Advanced time-domain calculations show that the conventional picture breaks down in the ultrafast regime, providing key insights into photo-activated, attosecond processes.

Helical coordination compounds that show promising antibiotic activity in aqueous media have been assembled directly in their optically pure form, without the need for a resolution step.

The classic organometallic compound ferrocene has been combined with a unique diiron unit in the latest synthetic analogue of an enzyme active site, achieving the three functionalities needed for a working model of diiron hydrogenase, itself of ancient origin.

A new type of protein–polymer conjugate provides improved stability without detrimentally affecting bioactivity, and thus offers great potential for the development of new peptide-based drugs.

The most complex non-DNA molecular knot prepared so far is self-assembled around a chloride anion from five metal cations, five bis-aldehyde and five bis-amine building blocks, in a one-pot reaction. The X-ray crystal structure of the 160-atom-loop pentafoil knot reveals a symmetrical closed-loop double helicate with a chloride anion held at its centre by ten CH···Cl⁻ hydrogen bonds.

The taxane diterpene family is structurally complex and exhibits a wide range of biological activities, best exemplified by the successful drug Taxol. Here, two of the least oxidized taxanes in the family, ‘taxadienone’ and taxadiene, are prepared by total synthesis on a gram scale. The concise synthetic route described herein provides a scalable, enantioselective entry to the taxane family of natural products.

The fastest catalysts in nature for producing and oxidizing hydrogen are [FeFe]-hydrogenases, which make use of an extra one-electron redox equivalent from an iron-sulfur cluster that is outside the core. Now, a ferrocene-based ligand that oxidizes at mild potential performs this cluster's role in an excellent synthetic hydrogenase model.

The self-assembly of monometallic moieties with organic ligands has proved to be a highly versatile approach for preparing a range of metal–ligand assemblies that are helical, optically pure and stable in aqueous solutions. One such iron(II) ‘flexicate’ system exhibits significant interactions with DNA, as well as promising antimicrobial activity properties.

Colloidal hybrid nanoparticles represent an emerging class of multifunctional artificial molecules. However, unlike actual molecules, their complexity is limited by the lack of a mechanism-driven design framework. Here, nanoparticle analogues of chemoselectivity, regiospecificity, molecular substituent effects, and coupling reactions are used to predictably synthesize hybrid nanoparticle trimers, tetramers, and oligomers.

A general reaction-discovery platform has been used for identification of a new multicomponent transformation. The approach entails rapid analysis of interfacial chemical reactions on arrays of self-assembled monolayers using mass spectrometry. This enabled identification of a simple organic phosphine that catalyses a previously unknown condensation of siloxy alkynes, aldehydes and amines.

Despite their potential roles in catalysis and materials science, the redox-induced dynamic structural changes in (sp²-carbon ligand)–(multiple metals)–(sp²-carbon ligand) systems are not well understood. Now, tetra-palladium sandwich complexes have been described that exhibit redox-switchable assembly of the metal centres or coupling of the ligands.

Poly(ethylene glycol) conjugates have been widely used to improve the stability of proteins for use as therapeutics, but this stability comes at the expense of binding affinity. Here, poly(carboxybetaine) — a zwitterionic polymer — is shown to provide increased stability while also enhancing binding due to its super-hydrophilic nature.

Oxygen has contributed to our understanding of the evolution of life on Earth by providing invaluable clues to geological processes — yet it still holds the key to some unsolved mysteries, as Mark H. Thiemens explains.