At first sight, it is not immediately discernible how molecular-weight measurements can be used for the determination of binding constants for protein–ligand complexes. Nevertheless, successful strategies have been developed for the quantitative analysis of protein–ligand binding by mass spectrometry (see scheme), which offers the distinct advantages of speed and the potential for automation.

The “tamed” hypofluorous acid complex HOF⋅CH₃CN has been found to be a convenient reagent for the expedient oxidation of azides to their corresponding nitro compounds. The method is quite versatile with both aromatic and aliphatic azides.

More than scratching the surface: Dip-pen nanolithography (DPN) is a new scanning-probe-based direct-write tool for generating surface-patterned chemical functionality on the sub-100-nm length-scale (see picture). This article introduces DPN and reviews the rapid growth of the field of DPN-related research and its impact on areas ranging from biological nanoarrays to patterned magnetic media to microelectromechanical systems (MEMs).

Space—the final frontier: A complementary approach to retrosynthetic analysis has been used to develop forward-synthetic analysis which forms the basis of diversity-oriented synthesis (see scheme). The goals of diversity-oriented synthesis include the development of pathways leading to the efficient (three- to five-step) synthesis of collections of small molecules having rich skeletal and stereochemical diversity.

Slippery when wet: Water molecules at the interface between a protein (e.g. bovine pancreatic phospholipase A2) and a micellar substrate act as a lubricant and facilitate movement and binding of the protein at the surface (see picture). Studies of the hydration dynamics before and after complexation reveal that these interactions are crucial for enzymatic function.

Silicon epitaxy on ZnS nanowires results in the formation of ZnS/Si core/shell nanowires; chemical removal of the zinc blende nanowire templates produces monocrystalline silicon tubular nanostructures with outer diameters of about 60–180 nm, wall thicknesses of about 20–60 nm, and lengths of several micrometers (see picture). The electron diffraction pattern of an individual nanostructure (inset) confirmed the presence of single-crystalline silicon.

Two steps forward: The glycosylated aminocoumarin antibiotic novobiocin (1) is produced by Streptomyces spheroides and inhibits the bacterial type II topoisomerase DNA gyrase. The sugar-tailoring enzymes NovP and NovN that catalyze the final two steps in novobiocin biosynthesis were overproduced in Escherichia coli and characterized as a methyltransferase and carbamoyltransferase, respectively.

Potent transition-metal complexes for asymmetric catalysis are formed from readily accessible N,P ligands constructed from basic N-heteroaryl building blocks (see structure). Their simple assembly should not be misconstrued: they posses several handles by which to tune both steric and electronic parameters. The potential of these ligands is demonstrated by the high levels of enantioselection they induce in such divergent processes as asymmetric hydrogenation and the Heck reaction.

Hierarchical self-assembly: Oligo(p-phenylenevinylene)s with pendant diamino triazine moieties can self-assemble through hydrogen-bonding interactions to give hexameric rosettes (see picture, left). These rosettes further organize into large supramolecular tubules (right) with perfect space filling.

Olefins can be converted into aziridines by using a chloramine-T/I₂ system, and silica and water as the reaction medium (see picture). Moreover, the ring-opening reaction of the resulting aziridine with an azide or a cyanide ion proceeds in the same medium.

“TADA!” is not the trumpet fanfare but the transannular Diels–Alder reaction concluding the synthesis of the tetracyclic core of the mangicols, a family of marine sesterterpenes. Further highlights in the synthesis include a novel chlorination and an intramolecular Nozaki–Hiyama–Kishi coupling reaction. Bn=benzyl.

The high reactivity of indoles has led to a new approach for the kinetic resolution of epoxides. [Cr(salen)] efficiently catalyzes a new CC bond-forming reaction that allows the kinetic resolution of cis and trans aromatic epoxides (see scheme). By employing the same catalytic system, different indolyl derivatives were obtained in high enantiomeric excesses (up to 98 %) by asymmetric ring opening of meso-stilbene oxide.

A molecular octopus: A ferromagnetic cubane cluster [{Cu^II(HL)}₄], which has eight vacant coordination sites on its pendent arms, undergoes metal-driven self-assembly to form an antiferromagnetic mixed-valent tetradecanuclear complex with a prismatic propeller-shaped {Cu^II₁₂Cu^I₂} core (see scheme).

An elegant model: The intermediates in both the hydride and carbomethoxy cycles, and in chain transfer for carboalkoxylation of ethene and CO–alkene copolymerization have been characterized for a highly active cationic palladium–diphosphane catalyst (see scheme). In contrast to previous reports on model systems, alkene insertion into the PdC(O)OMe and PdC(O)Me bonds is found to occur at comparable rates.

The fate of intermediate π radicals is crucial in Bu₃SnH-mediated cyclization by homolytic aromatic substitution, for example, of bromo compound 1 via radical 2 to give oxindole 3 (AIBN=azobisisobutyronitrile). The results indicate that the mechanism requires the abstraction of a hydrogen radical from the intermediate π radical by the radical initiator or a product of initiator breakdown, and also that arene solvents are not always the best solvents for radical reactions.

A high valent Mn^VO porphyrin dimer is prepared by peracid oxidation of an Mn^III dimer under basic conditions at room temperature (see scheme; mCPBA=m-chloroperbenzoic acid). The addition of an acid to a solution of the Mn^VO complex results in quantitative dioxygen evolution. Water and/or hydroxide ions are the sources of both the oxo ligand and the evolved dioxygen.

A super film: 2D sheet assemblies of alkylsilylated deoxyguanosine derivatives were formed by double intertape hydrogen bonding between hydrogen-bonded 1D tape motifs. Introduction of polar oxyethylene units at the sheet surface allowed the fabrication of a flexible, self-supporting supramolecular film (see figure) with a well-defined structural hierarchy.

Dealkylation of trialkylvinylsilanes: The direct electrophilic cleavage of one silicon–carbon bond of tetraorganosilanes activated by the intramolecular pentacoordination of a slightly nucleophilic ester or carboxylic acid group provides a novel route to silalactones (see scheme).

Very different reactivity of two types of cuprates: Treatment of a silyldichloromethyllithium compound with a copper reagent prepared from BuMgBr and CuCN gives the product of consecutive dibutylation. On the other hand, Bu₂CuLi⋅LiCN affords the butylation/cyanation product (see scheme, Si=Ph₂MeSi).

Do dendrimers in solution have a dense shell or a dense core? This question can be answered with the help of small-angle neutron scattering. The fully aromatic dendrimer G4-M shown here displays the expected rigid structure in solution and represents the first example of a real dense-shell dendrimer.

Getting under the surface of aging: The bulk structure of copper nanoparticles can be tailored during the preparation by exploiting known structure–activity relationships. Ageing of freshly precipitated precursors leads to characteristic phase transitions and enables control of microstrain and particle size (see picture) properties which influence catalytic activity.

A reaction that takes to water: The domino Michael addition/aldol condensation of salicylic aldehydes like 1 as the nucleophile and 2-cyclohexen-1-one (2) as the Michael acceptor provides 2,3,4,4a-tetrahydroxanthen-1-ones such as 3 in good yields. DABCO=1,4-diazabicyclo[2.2.2]octane.

Monolayer gold islands with a thickness of one or a few monolayers on an FeO(111) substrate are found to exhibit identical CO adsorption behavior as large gold particles (see picture). This result suggests that particle thickness does not play a significant role in CO adsorption, and therefore size effects seen for the low-temperature CO oxidation reaction are not related to quantum size effects.

And they all do it! Like PtAu⁺, the lighter dinuclear platinum–coinage-metal clusters PtCu⁺ and PtAg⁺ also mediate the C–N coupling of methane and ammonia. As the homonuclear clusters Pt₂⁺, Cu₂⁺, Ag₂⁺, and Au₂⁺ are inactive (see scheme), the particular electronic situation of the bimetallic clusters appears to be crucial for the outcome of this intriguing reaction.