B negative: By reduction of a 2-bromo-1,3,2-diazaborole Yamashita, Nozaki, and co-workers have obtained the first three-coordinate boryl anion (see formula), which provides an unprecedented and synthetically highly useful source for a nucleophilic boron species.

Calcium supplements for Grignard: The easy access of aryl calcium compounds in high yields now offers the possibility of investigating the properties and chemical behavior of these heavy Grignard reagents (see picture; C black, Ca purple, Cu yellow, O red). The key points are the nature of activation of the metal prior to use and the use of low reaction and handling temperatures to prevent side and decomposition reactions.

Inorganic, and yet more complex than an enzyme? The giant unit cells of Mg₂Al₃, NaCd₂, and Cu₄Cd₃ have challenged geometers of nature—so many beautiful polyhedra and networks to choose from. Could quantum mechanics help pick among alternative patterns? Indeed, simple calculations highlight building blocks derived from the MgCu₂ structure type, which pack together in interpenetrating regions of polar and nonpolar bonding (see scheme for NaCd₂).

Bottom-up and top-down nanofabrication: A fluorescent organic molecule bearing a self-assembly modulator was assembled in situ through a vapor-driven self-assembly process into strongly fluorescent spherical nanoparticles (about 30 nm in diameter) in the photochemically delineated regions of a polymer matrix (see picture; PAG: photoacid generator).

Must love cats.! Chiral amines catalyze the enantioselective addition of N-heterocyclic compounds to α,β-unsaturated compounds in high yields and with enantioselectivities of up to 94 % ee (see scheme; TMS=trimethylsilyl). The intermediates and transition states for the catalytic cycle were identified by performing DFT calculations.

SAMs in charge: The monohydrate and anhydrous forms of theophylline crystallize concomitantly from ethanol solutions, but hydrophilic thiol self-assembled monolayers (SAMs) promote the selective growth of the anhydrous form (see picture; C gray, H yellow, N blue, O red). This selectivity is a result of interfacial hydrogen bonding and geometric epitaxy.

A pocketful of coppers: Redox potentiometry and EPR experiments have confirmed that the active site of the particulate methane monooxygenase (pMMO), a membrane-bound enzyme that hydroxylates methane to methanol under ambient conditions, consists of one trinuclear copper cluster (see picture) and one type 2 copper site, in addition to the dinuclear copper cluster revealed previously by X-ray crystallography.

Proof positive: Infrared multiphoton dissociation (IRMPD) spectroscopy, with the tunable IR radiation of a free-electron laser source, provides positive identification of alkoxide adducts of 1,3,5-trinitrobenzene as prototypical anionic σ complexes in the gas phase (see calculated IR spectrum of 1 under the experimental IRMPD spectrum; N blue, O green, C gray, H light gray).

Don't FRET: The first successful combination of optical-tweezers force microscopy and single-molecule fluorescence resonant energy transfer (FRET) is demonstrated with a force sensor based on a DNA hairpin (see picture). As the hairpin is opened and closed by the optical tweezers, the structural change is simultaneously monitored by the FRET emission from fluorescence labels.

Winning the three-legged race: Rapid self-organization of a tripodal aromatic dipeptide conjugate on a tris(2-aminoethyl)amine scaffold leads to a vesicular morphology (upper image). The structures can trap a fluorescent dye (lower image) and release it upon acidification, suggesting the use of such stimuli-responsive materials as potential delivery vehicles.

Eukaryotes have evolved complex cellular responses to double-stranded RNA. The quantities of short interfering RNA (siRNA) can be determined rapidly by using 96-well arrays of the carnation Italian ringspot virus (CIRV) p19 protein, which binds double-stranded siRNAs with nanomolar affinity and discriminates siRNA according to length. Two compounds were found to inhibit siRNA binding to CIRV p19 by alkylating active-site cysteine residues (see diagram).

What makes it go linear? The synthesis of the first polycyanide compounds of a 5f element (see picture, U green, N blue, C white) supports the idea that the geometry of metallocenes depends on both the metal oxidation state and the size and shape of the equatorial ligands. Theoretical investigations reveal that the stability of these novel linear π-sandwich compounds is determined by the availability of f orbitals.

The chosen one: A molecular cage has been shown to form pseudorotaxane-like complexes with threaded anthraquinone and squaraine units in the presence of templating Na⁺ ions (see picture). The complexation and decomplexation of the pseudorotaxane complexes in solution occur with significant color changes which allows this ion-specific templating effect to be easily monitored with the naked eye.

Tracing glucose uptake: Fluorescent glucose analogues were synthesized, and the importance of stereochemistry for cellular uptake efficiency was demonstrated. The chiral bioprobe 1 showed superior properties as a glucose-uptake tracer. The cellular uptake of 1 was demonstrated under various concentrations of D-glucose. A screening system was developed for the discovery of anticancer agents by the measurement of glucose uptake in cancer cells with 1.

Special delivery: Functionalized single-walled nanotubes (SWNT) can be used as molecular transporters to shuttle short interfering RNA (siRNA) into human T cells and primary cells and silence the expression of HIV-specific cell-surface receptors and coreceptors (see picture; scale bars 40 μm). This silencing effect, known to block HIV viral entry and reduce infection, is superior to that observed with conventional liposome-based nonviral delivery agents.

Every nucleolus has a silver lining: Formation of silver nanoclusters by fluorescence photoactivation was used for the staining of cells at low silver nitrate concentrations and ambient temperature. The picture shows picosecond lifetime images of peptide-encapsulated silver nanoclusters within NIH 3T3 cells.

The surrounding shapes the box: The zinc porphyrin dimer 1 bearing pyridyl groups can chiroptically sense an asymmetric hydrocarbon, such as limonene, by forming the homochiral box-shaped tetrameric assembly BOX_⊥. As the BOX_⊥ formed is enantiomerically enriched, the optical purity as well as the absolute configuration of the solvent limonene can be determined.

A pHunction of pH: The silver nanoprism fusion process can be turned on and off as a function of the pH value during photochemical synthesis. With appropriate pH regulation (see TEM images, middle and right), one can achieve excellent control over the nanoprism edge length with a fixed 10-nm thickness and the corresponding plasmon bands, which span the visible and NIR range (see extinction spectra, left).

Tackle-resistant bacteria: Determination of the 3D structure of the antibiotic lysobactin has led to its total synthesis and resulted in a high-yielding macrolactamization step. The minimal use of protecting groups allowed preorganization of the side chains to steer the cyclization. Thus, a new chemical route has been developed in the search for innovative antibiotic lead structures.

One thing leads to another: Reactions of the cationic BN vinylidene analogues 1-[BAr^F₄] (R=Cy, iPr; Ar^F=3,5-(CF₃)₂C₆H₃) towards dicyclohexylcarbodiimide proceed by unprecedented insertion chemistry for terminal borylene complexes. Controlled, stepwise insertion into the FeB and BN bonds is demonstrated, sequentially forming four-membered rings linked at a spirocyclic boronium center.

Crystal clear: A detailed conformational characterization of a synthetic analogue of the peptide antibiotic alamethicin (see structure; C gray, N blue, O red) has been achieved by X-ray diffraction. The high-resolution structure of this analogue, which incorporates a spin probe, paves the way for a better understanding of the mode of action of alamethicin.

Build a bridge: Strong interactions between zirconium-activated indium tin oxide (ITO) nanoparticles and phosphates are utilized to label nucleic acids with multiple ITO nanoparticles under very mild conditions. The electrically conductive ITO nanoparticle network formed bridges the gap between a pair of interdigitated electrodes, allowing the detection of nucleic acids at subpicomolar levels with high specificity.

Gotta have copper: DFT studies indicate that the performance of heterogeneous epoxidation catalysts depends on the first step in the reaction between oxygen atoms and propylene molecules coadsorbed on the metal surface (see picture; C yellow, H light blue, O red). The high basicity of oxygen atoms on silver favors allylic hydrogen stripping, whereas the low basicity of oxygen atoms on copper favors metallacycle formation and subsequent epoxidation.

Influential guests: An abrupt spin-crossover transition is exhibited by a nanoporous framework material that consists of interpenetrated two-dimensional grids linked by hydrogen-bonding interactions. Desorption of guest molecules from the highly robust host lattice occurs by a single-crystal-to-single-crystal transformation and leads to subtle changes in the framework structure and spin-crossover properties.

High and dry: The synthesis in vitro of longer-chain cellulose with more than 100 anhydrous glucopyranose units in the polymer has been performed by a new technique for glycosynthesis. This method uses enzymatic polymerization with enzyme/surfactant complexes that act in nonaqueous organic media.

Color me yellow: Poly(ADP-ribose) polymerases (PARPs) play a major role in cellular survival and maintenance of energy stores after genotoxic insult. The colorimetric PARP substrate ADP-ribose-pNP can be used to monitor PARP activity. By monitoring the production of p-nitrophenolate, the kinetic parameters of PARP-1, tankyrase, and PARP-4 could be evaluated. ADP=adenosine diphosphate, pNP=p-nitrophenoxy.

Two unexpected transformations: The reaction of the Huisgen zwitterion derived from triphenylphosphane and diisopropyl azodicarboxylate (DIAD) with chalcones affords functionalized pyrazolines. In contrast, the reaction with dienones affords pyrazolopyridazines, presumably by Diels–Alder reaction of the initially formed pyrazoline with excess DIAD (see scheme).

Internal affairs: Indoles, benzofurans, and enol lactones are formed chemoselectively from the rhodium-catalyzed cycloisomerization reaction of easily prepared alkynyl aniline substrates (see scheme, cod=cycloocta-1,5-diene, DMF=N,N-dimethylformamide). The reaction may proceed by nucleophilic capture of a vinylidene intermediate. Indoles are formed under mild conditions using low catalyst loadings.

Without a trace: Benzylic nitroalkanes are reduced to the corresponding parent alkanes in good yields by using a simple procedure involving heterolytic CN bond cleavage (see scheme). Traceless removal of the nitro group leaves behind a stereogenic center that may otherwise be difficult to install. This reaction significantly expands the scope of building blocks that can be accessed.

Simple ligands, catalyst, and conditions: The combination of readily prepared unsymmetrical pyridine–imine ligands and [CpRu(CH₃CN)₃][PF₆] (Cp=C₅H₅) affords regio- and enantioselective Carroll rearrangements (see scheme; b/l= branched-to-linear ratio). This reaction represents the first example of Ru-catalyzed enantioselective CC bond-forming allylic substitution.

A general get-together: The Cu-catalyzed cross-coupling reaction of primary-alkyl halides with primary-, secondary-, and tertiary-alkyl and phenyl Grignard reagents proceeds efficiently in THF under reflux in the presence of 1-phenylpropyne (see scheme). The reaction is also applicable to alkyl mesylates (OMs) and tosylates (OTs). The reactivities of alkylX with a Grignard reagent increase in the order X=Cl<F<OMs<OTs<Br.

Excellent conjugation: The novel azoporphyrins (1,2-bis(porphyrinyl)diazenes) have been prepared by using copper-catalyzed coupling of primary amines. The structure of the azo(triphenylporphyrin) was determined by X-ray crystallography (see picture). The azo linker provides an excellent conjugating pathway for expansion of porphyrin π conjugation.

The elusive triplet state of indigo (see picture) has been fully characterized by energy-transfer pulse radiolysis and photoacoustic calorimetry. The triplet energy is (1.04±0.10) eV and the singlet-to-triplet intersystem crossing yield in solution is ϕ_ISC=0.0066. Inefficient intersystem crossing, low triplet energy, and fast internal conversion of the singlet state likely contribute to the high stability of indigo.

Low catalyst loadings, high enantioselectivities, mild conditions, and fast reaction times are the important features of the first enantioselective organocatalytic electrocyclic reaction: a Nazarov cyclization leading to the synthesis of substituted five-membered rings with a chiral Brønsted acid as a catalyst (see scheme). A further advantage of this method is the possible entry to all four diastereomers of the product.

Click snapshot: In an aprotic medium, a copper(I) triazolide complex is synthesized from a sterically hindered copper acetylide and an organoazide (see scheme: yellow Cu, blue N, dark gray C, gray H). This result provides direct evidence for such a complex, which had previously been hypothesized.

Elimination round: Dehydroiodination occurs when transient phosphinidene complex 1 is treated with iodomethane and diiodomethane, thus formally eliminating CH₂ and CHI and giving in both cases complex 2 (see scheme; R=CH(SiMe₃)₂; R′=CH₃, CH₂I). The overall reactions represent examples of unprecedented PC bond-cleavage reactions, and proceed under unusually mild conditions.

Cooperation is key: Peptide and saccharide portions cooperate in sialyl Lewis^x glycopeptides and their mimetics in the fucose and sialic acid parts (see formula), resulting in up to greater than 100-fold stronger binding to E-selectin. The synthesis provided sialyl Lewis^x amino acids in a form sufficiently acid-stable for application in automated solid-phase syntheses of glycopeptides based on acid-sensitive linkers.

Game, set, and mismatch: In a new method for the detection of base-pair mismatches, an immobilized DNA strand with a cleavage site (black square) and a detection tag (red circle) is hybridized with the target strand. If the target nucleotide has a mismatch, then the marker is released from the solid phase (see scheme).