Volume 4 Issue 8, August 2012

Jean-François Lutz wonders whether chemists should slow down.

Claudia Turro from The Ohio State University talks Nature Chemistry through the different binding modes small metal complexes can adopt when interacting with DNA — and why elucidating them in detail matters.

The interactions between ruthenium complexes and DNA duplexes, elucidated in detail in three different crystal structures, have been found to occur through the minor groove — an unexpected binding mode, but perhaps not such a strange one.

An electrochemical sensor that relies on displacement of a 'neutralizer' from a surface-bound, charged probe molecule by the analyte enables the use of a single platform for the detection of multiple analytes irrespective of their charge.

Oxide materials typically used as supports for the active metal nanoparticles of heterogeneous catalysts are known to influence catalytic activity through strong metal–support interactions. Researchers have now revealed electronic interactions between platinum and ceria that go well beyond known effects and lead to excellent catalytic activity.

Organic molecular building blocks can self-assemble into structures with interesting optoelectronic properties. A combination of selective chemistry, spectroscopy and thorough theoretical analysis of a double-wall supramolecular nanotube has now led to a detailed model of its structure and internal excitonic coupling.

The efficient production of stable bioactive proteins often requires the selective formation of several disulfide crosslinks. Two recent studies have now shown that replacing cysteine with selenocysteine in the unfolded protein can autocatalyse the formation of the desired crosslinks.

Novel concepts in asymmetric catalysis have the potential to open up previously inaccessible reaction space. This Review reflects on the origins of an area that has undergone dramatic recent advancement: the use of chiral anions in asymmetric catalysis. Details of a selection of the latest examples are also given.

A ‘light switch’ ruthenium complex is known to show enhanced luminescence in the presence of DNA mismatches — emerging targets for cancer diagnostics and therapeutics — but the way it interacts with DNA has remained unclear. Now, metalloinsertion into and metallointercalation at the minor groove of the double helix have been unambiguously observed in a high-resolution crystal structure.

Elucidating how small molecules bind to DNA is crucial to bio-sensing and therapy applications. Two crystal structures now show the binding modes of a ‘light switch’ ruthenium complex — whose luminescence in solution increases in the presence of DNA — with oligonucleotide duplexes containing either TA/TA or AT/AT central steps, revealing a specific intercalation mode with the TA/TA species.

A bench-stable, aryl sulfonyl triazene is described that can be appended to alcohols or amines and used as a directing group to effect remote desaturation of unactivated aliphatics to produce olefins. The reaction is mild, operationally simple, requires no added metals and produces unsaturated tosylates or tosylamides available for further functionalization.

Steric effects are a key concept for understanding chemical reactivity. Now, by aligning reactants through control of the polarization of the infrared laser in a crossed-beam experiment, a three-dimensional view of how a reaction proceeds is reported. The results show striking dependences on the direction from which the laser-aligned reagents approach.

A universal detector of small molecules, proteins and nucleic acids is described that relies on the displacement of a neutralizer molecule from a sensor surface. When the neutralizer is displaced by an analyte, an electrochemical signal is generated. Ultrasensitive limits of detection are achieved, and a new record for the electrochemical detection of bacteria (0.15 colony-forming units per microlitre) is reported.

Organometallic reagents are widely used as nucleophiles in asymmetric catalysis. Here, alkylmetal species generated in situ by hydrometallation of alkenes are used in enantioselective copper-catalysed C–C bond formation. The process is formally an asymmetric reductive coupling of an alkene to an enone, and tolerates many functional groups.

The collective excited states (excitons) in supramolecular light-harvesting systems depend intimately on their structure and it is crucial to understand how these states interact. Now it is shown that simple redox chemistry can be used to address this fundamental question by simplifying the complex excitonic interactions in such multichromophoric systems.

Chemical glycosylations are perhaps the most important reactions in glycoscience, but the mechanisms are not well understood. Here, quantum chemical calculations combined with natural-abundance NMR measurements of ¹³C kinetic isotope effects reveal both associative and dissociative mechanisms at the extremes of a continuum that depends on the relative stereochemistry of the substrate and the anomeric configuration of the product.

Simple uranium complexes, UX₃, are shown to disproportionate in the presence of a reducing agent under mild conditions, cooperatively binding and reducing arenes. This enables arene C–H bond activation and borylation, and the trapping of reactive substituted arenes in inverse sandwich complexes.

One of the goals for devices using organic semiconductors is to make the materials themselves multifunctional or tunable, reducing the complexity of the device. Now, a film created by blending two components is shown to be phototunable with bistable energy levels and has been used in an organic thin-film transistor.

Marinomycin A is a member of a new class of bis-salicylate-containing polyene macrodiolide, with potent antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF). Here, a triply convergent synthesis of this agent is described that uses the salicylate moiety as a novel molecular switch for the chemoselective construction of the macrodiolide.

Although first known among chemists for its noxious or lifeless character, nitrogen was later revealed to be involved in many life, and death, processes. Michael Tarselli ponders on this unforeseen characteristic.

Photosensitive metal complexes that are able to bind to DNA duplexes hold promise for diagnostic and therapeutic applications — but the precise details of how they interact with DNA need to be better understood. A collection of articles in this focus highlight some of the latest advances in elucidating their binding modes as well as challenges associated with this area of research.