Sticky business: Marine mussels (see picture) affix themselves to rocks with a system of threads and adhesive plaques. Emerging results are showing that iron–protein interactions help mussels stick by playing two roles: initiating material formation and enhancing mechanical performance.

Joined at the hip: By linking two salen ligands together with a strap of appropriate size and shape, the effectiveness of a bimetallic titanium(salen) complex as a catalyst for asymmetric cyanohydrin synthesis can be increased by up to two orders of magnitude. The optimal catalyst is active at a catalyst loading as low as 0.0005 mol % and will accept both trimethylsilyl cyanide and sodium cyanide/acetic anhydride as the cyanide source (see scheme).

Helping chemists help chemists: What reactions do medicinal chemists use in drug discovery? (The pie chart shows a snapshot from one unit at GlaxoSmith-Kline.) What criteria do they use to select synthetic methodology? Why are arrays (small focused libraries) so powerful in the lead-optimization process? These questions are considered in this Minireview, which also describes attempts to expand the number of robust reactions available to medicinal chemists.

Since the industrial revolution began about 150 years ago, the concentration of greenhouse gases such as CO₂ in the atmosphere has increased dramatically, with corresponding consequences for the climate. For over 25 years, destruction of the ozone layer (pink and green regions on the globe), which is caused by chlorofluorocarbons, has also been observed. The future development of the ozone layer and of the climate are closely related to each other.

Light controls size: A novel type of self-organized supramolecular nanoparticles can change their size upon irradiation with UV light (see picture). The doubly responsive system combines a light-triggered size with a pH-induced switching between nanoscale aggregates and molecular building blocks. The nano-objects form by a combination of ionic and π–π interactions between macro-ions and dye ions.

Adding 2Ns: Palladium catalysis introduces two nitrogen groups in a new regio and chemoselective diamination of non-activated alkenes that proceeds under entirely intermolecular reaction control. This palladium-catalyzed reaction employs commercial nitrogen sources in combination with a hypervalent iodo(III) reagent as oxidant (see scheme; Tos=toluenesulfonyl).

The key nickel enzyme for methanogenesis (MCR) catalyzes the formation of CH₃D and CH₂D₂ in a deuterated medium. CH₂D₂ is formed by an exchange of deuterium into the S-methyl group of the substrate. Deuterium is incorporated at both carbon atoms of the S-ethyl group of ethyl coenzyme M, and a ¹³C label is rapidly scrambled within the ethyl group (see scheme). Thus, at least one intermediate is formed and the isotope exchange pattern is consistent with formation of a σ-alkane–nickel complex.

Breaking out: Liposomes that are adsorbed onto porous CaCO₃ particles and that contain the peroxidase substrate Amplex Red (AR) are disrupted by ultrasonic treatment. The substrate is released and diffuses into the inner part of the multicompartment containers where the peroxidase enzyme is found, and the enzymatic reaction is triggered. This approach may be useful for the simultaneous delivery of multiple molecules into cells.

In the iron age: A readily accessible, active iron catalyst serves in the straightforward, catalytic transfer hydrogenation of imines (see scheme). A series of imines are converted into chiral amines in high yields and very good enantioselectivities. This method should find broad application in the search for bioactive chiral amines.

Atom efficiency and selectivity are the key features of the first homogeneously catalyzed amination of secondary alcohols with ammonia to give the corresponding primary amines (see scheme). This novel amination method relies on the commercially available catalyst [Ru₃(CO)₁₂]/cataCXium PCy and does not require any additional source of hydrogen.

Hydrogen shuttle: For the first time secondary alcohols and ammonia can be directly converted into primary amines with a selectivity of up to 99 % by using a simple ruthenium/phosphine catalyst (see scheme; R¹, R²= alkyl, aryl, alkenyl; M=[Ru₃(CO)₁₂]; and L=phosphine ligand).

No toxic compounds such as KCN and no thermal activation is required for the preparation of Au/MgF₂ complexes by a simple and facile “incipient wetness impregnation” method in which hydrogen tetrachloroaurate (HAuCl₄) is the gold precursor. One of the complexes prepared exhibits unique catalytic properties and serves as a heterogeneous catalyst for the highly diastereoselective one-pot synthesis of (±)-menthol from citronellal (see picture).

An appealing couple: The unprecedented insertion of the nitrosonium cation into a tetrahedral edge of white phosphorus forms the highly reactive [P₄NO]⁺ cation (see picture). The synthesis, characterization, and applications are discussed, and NO₂[Al(OC(CF₃)₃)₄] is presented as an easily synthesized oxidant.

Asymmetric conjugate addition of arylboroxines to borylalkenes proceed in the presence of a chiral bisphosphine/rhodium complex as a catalyst to give chiral β-arylalkylboranes with high enantioselectivities (see scheme). [O]=H₂O₂/NaOH.

Tripping the light fantastic: A fluorescently active cryptand containing an anthracene fragment catalyzes the photoinduced reduction of Cu^II to Cu^I with simultaneous oxidation of water to oxygen (see scheme).

This way and that: Triazolylbiferrocenyl dendrimers can be synthesized with up to 729 termini. Oxidation results in isolable mixed-valence dendrimers (see picture). In electrochemical studies, these species can recognize ATP²⁻ and Pd^II, and they can be used to stabilize Pd nanoparticle catalysts.

Metal-based catalysts: The title reaction provided the chiral adducts in high yields, excellent enantiomeric excess, and high Z/E selectivity. A combined NMR/DFT study revealed a key intermediate for the stereoselective reaction and a possible reaction mechanism (see the optimized transition-state structure).

A new generation: The incorporation of N-heterocyclic carbene/pyridine-based ruthenium sensitizers derived from benzimidazolium salts into dye-sensitized solar cells results in superior current densities, cell voltages, and photoelectric conversion efficiencies. The performance of a solar cell sensitized with CBTR (see picture) exceeded that of the traditional N719 cell.

Holey support: The generation of a porous coating of SiO₂ on Pt-decorated TiO₂ nanofibers enables the preparation of a sinter-resistant catalytic system (see picture). The Pt nanoparticles could resist sintering at temperatures up to 750 °C in air, as the SiO₂ coating acts as a physical barrier that slows down surface migration, but the system remained catalytically active because of the porous nature of the coating.

It takes two to tango! A combination of partially reduced chiral H₈-TBOx chromium catalyst 1 and achiral cobalt porphine co-catalyst 2 (Ar=p-anisyl) led to an enhancement in enantioselectivity by suppression of the background process that presumably proceeds through an organomanganese species.

Captured and bound! Kdo, a monosaccharide, and an immobilized capture molecule form a covalent adduct that can be detected by adduct-specific antibodies (see scheme). The recognition yields a signal that is proportional to the amount of Kdo present in solution. This small-molecule sensor should be applicable for any small molecule that can react to give an immunogenic adduct.

The lead-inhibited active site of a zinc-binding metalloenzyme in a thiol-rich coordination environment (PbS₃) has been modeled by homoleptic three-strand coiled-coil peptides and characterized using natural-abundance ²⁰⁷Pb NMR spectroscopy (see picture: ²⁰⁷Pb NMR signals from two binding sites of the same protein). ²⁰⁷Pb NMR spectroscopy could thus be used to identify and characterize important human proteins associated with lead toxicity.

On a Rh-oll: Rhodium(I)-catalyzed CH activations of ketimines and subsequent carborhodation of an allene led to an allyl metal species, which then allylated the imine directing group to give highly functionalized methylene dihydroindenyl amines (see scheme) with excellent regio- and diastereoselectivity.

Back to basics: Coupled with MALDI-TOF MS, laser-assisted proteolysis (see schematic illustration) enabled rapid protein digestion and peptide mapping without the need for enzyme immobilization to increase the efficiency of tryptic digestion. Protein solutions containing trypsin were digested in less than a minute upon irradiation at 808 nm with a laser.

The source of the problem: Experiments with isotopically labeled water can be used to unambiguously assign the source of oxygen in a nonheme manganese(IV) oxo complex. The complex, which was generated using water as an oxygen source and cerium(IV) as an oxidant (see picture), shows reactivities in the activation of CH bonds of alkyl-functionalized aromatic molecules and the oxidation of aromatic substrates (sub) and benzyl alcohol.

Body image: Self-activating Huisgen 1,3-dipolar cycloaddition and 6π azaelectrocyclization of lysine-based dendrimers (see picture) enable the in vivo dynamics and organ-specific accumulation of N-glycans to be visualized. The sugar structure and glycosyl bond linkages of N-glycans control the whole-body trafficking of the clusters in nude mice and a cancer model.

A new family of chitin–silica nanocomposites has been synthesized by using a versatile colloid-based combination of self-assembly and sol–gel chemistry (see picture). Various textures and morphologies can be obtained by adjusting the evaporation-based processes or by applying external fields. After calcination, textures and birefringence are preserved in the resulting mesoporous silicas.

Localized or delocalized? For the first time, a cyclic oligoaniline, hexaaza[1₆]paracyclophane, has been prepared (see picture; carbon: gray; nitrogen: blue; hydrogen: light gray). The macrocycle exhibits a high electron-donating ability, and furthermore, the spin of the corresponding radical cation was delocalized over the macrocyclic molecular backbone.

We are family: Triazacoronene derivatives have been synthesized in four steps from veratrole by using a threefold Pictet–Spengler reaction as the key step (see picture). They have good photophysical and electronical properties, thermal stability, and solubility, thus rendering them promising candidates as electron-transport materials.

Cut here to cure: Doxorubicin attached to pH-sensitive mesoporous silica nanoparticles (MSN-hydrazone-Dox) shows potential in the chemotherapeutic treatment of liver cancer. Hydrolysis of the pH-sensitive hydrazone bond in the acidic environment of endosomes/lysosomes (see picture) releases Dox intracellularly from the MSN nanochannels, resulting in highly efficient apoptotic cell death.

Getting in shape: Stable pointed-oval-shaped micelles of uniform size and shape (see TEM image) were prepared by extending the crystallization-driven living self-assembly method to crystalline core-forming polyferrocenylsilane diblock copolymers with corona-forming coblocks of poly(2-vinylpyridine) and polyphosphazene. The pointed-oval-shaped micelles were subsequently used as precursors to hierarchical micelle architectures.

All for one and one for all: Molecules with multiple conjugated photochromic boryl units undergo photoisomerization on a single boryl unit only. This single boryl switching causes fluorescence quenching of the entire molecule, which is greatly amplified with increasing numbers of switchable boryl units in the molecule.

Relocation, relocation: Inactivation of the mitotic kinesin MKLP-2 by a specific small-molecule inhibitor (1) leads to failure in the recruitment of the chromosome passenger protein (survivin, red) to the central spindle (microtubules, green) during anaphase chromosome segregation (DNA, blue).

Fighting against windmills: Highly homogeneous, well-defined, and finite “windmill”- and square-rod-shaped supramolecular architectures were formed by the self-assembly of a short helical β peptide in aqueous solution (see picture). The reproducible formation of the unprecedented 3D shapes could be controlled by the use of a surfactant of different concentrations.

Well-ordered superarrays of exceptionally large period (22 nm) and involving a substantial number of hexahydroxytriphenylene molecules (20×20 superlattice) form on a Ag(111) surface. The superstructure (see picture; triangular pattern) is an intrinsic property of the system and, remarkably, it does not depend on global surface coverage (lower right: partial structure).

Putting a number on it: MALDI-TOF MS enabled direct quantification of the cellular uptake of cell-penetrating peptides (CPPs) by MDA-MB-231 breast cancer cells. This sensitive general strategy (see schematic representation), which requires no purification or separation steps, relies on the enhancement and discrimination of the MS signals of an α-cyano-4-hydroxycinnamic acid tag in a neutral α-cyano-4-hydroxycinnamic methyl ester matrix.

Support framework: Post-synthesis modification of an interpenetrating Zn-based chiral metal–organic framework with Ti(OiPr)₄ results in a Lewis acidic catalyst (see picture; gray C, white H, red O, green Ti) with modest enantioselectivity in the asymmetric addition of diethylzinc to aldehydes. The Ti(OiPr)₄-treated framework contains single-crystal to single-crystal cross-linking of the two interpenetrating networks.

Not so far away from me: Reductive cleavage of a disulfide ligand with Cu^I leads to the formation of a new mixed-valent Cu^IICu^I complex (see picture). Combined X-ray and theoretical investigations highlight the presence of a striking Cu₂S core containing a CuCu bond, and solution studies also indicate a high degree of delocalization.

Layered cobalt hydroxide nanocones intercalated with dodecyl sulfate (DS) ions (see scheme; OH⁻ blue, Co green dots, DS ions red) could be synthesized by the microwave-assisted rolling of lamellar structures. The cones could be exfoliated into cobalt hydroxide nanosheets and converted into CoOOH and Co₃O₄ nanocones.

Hydrogen-atom transfer from a thiol group to the CO₂ radical anion is a fast and selective downhill process in a gas-phase water cluster. This suggests that placing a thiol group near the site of electron transfer to CO₂ in a nanostructured electrochemical environment allows the selective formation of formic acid (see picture; dark gray C, light gray H, red O, yellow S).

A radical interaction has been employed as the recognition motif in the template-directed synthesis of a [2]rotaxane composed of cyclobis(paraquat-p-phenylene) and a viologen derivative. The ruthenium tris(bipyridine)/triethanolamine system is used as the electron-transfer photocatalyst to generate the necessary radical cation components that result in the formation of an inclusion complex. A stoppering reaction follows to form the mechanical bond.

Zinc links: Solid-state desolvation of the dimeric alkoxide [{tBuZn(μ-OtBu)(thf)}₂] leads to a trimer [{tBuZnOtBu}₃] with a unique core structure; subsequent grinding affords the tetrameric cubane [{tBuZnOtBu}₄]. This approach demonstrates a new direction in the generation of metal alkoxide clusters.