New cats, new tricks: Complementary iridium catalysts enable the Z-selective catalytic addition of acid chlorides to alkynes. Depending on the ligand, the reaction proceeds with or without decarbonylation to give β-chlorovinyl-substituted arenes or ketones: useful intermediates for the synthesis of heterocycles. cod=cyclooctadiene, IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), RuPhos=2-dicyclohexylphosphanyl-2′,6′-diisopropoxy-1,1′-biphenyl.

Look again: The X-ray single crystals structure determination of polyethylene glycol chains reported at the beginning of 2009 was not the first X-ray structure. The fact that old fiber and freeze-dried structure reports from the 1960s were overlooked points out weak spots in searches of chemical and crystallographic databases.

The rich get richer and the poor get poorer: More than 100 years ago the 1909 Nobel laureate Wilhelm Ostwald explained how large crystals grow at the expense of small crystals. This principle forms the basis for the recently discovered method for the conversion of racemic crystal mixtures into homochiral crystals by grinding-induced attrition.

The “Lord of the Rings”: The direct chemical manipulation of the indole system is a long-standing synthetic shortcut to challenging molecular architectures which recently entered a new dimension through the introduction of innovative catalytic systems and techniques. This Review highlights the new aspects that have had made a deep impact on this topic over the last few years: efficiency, selectivity, and environmental friendliness.

Holey balls! Novel microspheres made up of nanoplates have been fabricated by porphyrin-polymer-assisted supramolecular self-assembly of C₆₀. The obtained C₆₀ microspheres are single-crystalline and exhibit pure fcc structure. This is a rare example of a hierarchical supramolecular architecture fabricated by the self-assembly of unmodified C₆₀.

Chiral effectiveness: The title transformation is applicable to a wide variety of substrates to give chiral cyclohexenones in high yields and with excellent enantioselectivity (see scheme). To clarify the origin of the enantioselectivity ONIOM calculations were carried out

Three's company: The first genuine ternary colloidal crystal (see picture) is composed of PbSe nanocrystals of two different diameters (blue and green) and of CdSe nanocrystals (red). Electron tomography shows that the superlattice is isostructural with the atomic lattice AlMgB₄.

Going live: A protein-labeling method based on the use of a single amino acid tag—an N-terminal cysteine residue—and small-molecule probes containing a cyanobenzothiazole (CBT) unit has been used for the specific fluorescence labeling of proteins in vitro and at the surface of live cells (see scheme). This simple ligation reaction proceeds with a high degree of specificity under physiological conditions. Rd: a rhodamine dye; TEV: tobacco etch virus.

Gilded rafts: Oligomeric 2D raft clusters {M[m]}_n (M=Cu, n=3; M=Ag or Au, n=4; see picture) with the same bridging metalloligand [m]={CpMo(CO)₃} were prepared and structurally characterized. The ν₂-triangular (M=Cu) or ν₂-square (M=Ag, Au) structures of their metal–metal-bonded cores allow comparative evaluation of the d¹⁰⋅⋅⋅d¹⁰ interactions, and theoretical calculations point to a favorable contribution of diagonal Au⋅⋅⋅Au or Ag⋅⋅⋅Ag interactions.

Low level: The amount of arsenic in Bangladeshi well water and in bottled drinking water and Mississippi tap water are indicated by a dynamic light scattering (DLS) assay. Label-free gold nanoparticles are used in a selective colorimetric assay (see picture) and in a highly sensitive DLS assay for the recognition of arsenic in concentrations as low as 3 ppt.

A chromophore–catalyst dyad assembly of ruthenium polypyridyl complexes has been prepared, structurally and electronically characterized, and its proton-coupled multielectron photooxidation reactivity demonstrated by the visible sunlight-driven catalytic oxidation of aliphatic and benzyl alcohols into their corresponding aldehydes or ketones with high selectivities and over 100 turnover cycles in water, at ambient conditions.

Peptides that make bacteria RE coil: A peptide system designed to regulate antimicrobial intervention switches between antimicrobial and inactive forms. The regulator comprises two α-helical sequences. One of them, R coil, binds to microbial membranes and acts as an antimicrobial component, and is inactivated by the other, E coil, a membrane-inactive peptide (see picture).

Wiring photoelectrodes: Vertically aligned silicon nanowires were chemically synthesized and tested for solar-energy harnessing. Growth experiments reveal that such nanowire arrays can be obtained when the growth is slow. Photoelectrochemical studies validate that silicon nanowires are promising candidates for efficient solar cells.

On the double: Dimerization of monomeric peptide ligands towards the PDZ domains of the protein PSD-95 (postsynaptic density 95) leads to potent inhibitors of protein–protein interactions with stability in blood plasma. Optimization of the length of the polyethylene glycol linker results in unprecedented affinity for inhibitors of the PDZ1-2 domain (see picture).

One catalyst, three bonds: The title reaction between propiolic acids and unactivated olefins (see scheme; O red, Cl green) results in vicinal functionalization of the olefin, with the formation of new CC and CO bonds. Structurally complex 6,7,5-tricyclic ring systems are formed in a single step by this cascade chloropalladation and formal [3+2] cycloaddition.

Heterocyclic hot pot: Platinum(II)-catalyzed syntheses of indoles and isoquinolines from isocyanates, which are derived from a Hofmann-type rearrangement of amides using a hypervalent iodine reagent, are described. C₂-symmetric macrocyclic bis(indole)s can also be synthesized from transannulation of C₂-symmetric macrocyclic bis(alkyne carbamate) intermediates.

Initial steps of bimetallic Ru–Os cluster formation on MgO in the presence of H₂ are analyzed by EXAFS and IR spectroscopy. RuOs bond formation takes place after decarbonylation of Ru₃ clusters and subsequently, at higher temperatures, of Os₃ clusters to generate coordinative unsaturation (see scheme).

Zero Ge! Reductions of an N-heterocyclic carbene (NHC) adduct of GeCl₂ with magnesium(I) dimers afford a dimeric compound (see picture), which structural and theoretical studies show to contain a singlet digermanium(0) fragment :GeGe: datively coordinated by two NHC ligands.

What a relief! In 1955, strain release was put forward as a reactivity factor to explain the differing reactivity of axial and equitorial alcohols during oxidation. The same rationale may account for the differing rates of activation between axial and equitorial CH bonds in CH activation processes (see scheme).

Just say NNO: Reaction of [tBu₃PN₂O(B(C₆H₄F)₃)] with 1, 1.5, or 2 equivalents of Zn(C₆F₅)₂ affords the species [{tBu₃PN₂OZn(C₆F₅)₂}₂], [{tBu₃PN₂OZn(C₆F₅)₂}₂Zn(C₆F₅)₂], and [tBu₃PN₂O{Zn(C₆F₅)₂}₂] (see structure; red Zn (large sphere), O (small sphere), green N, yellow P) displaying unique binding modes of Zn to the phosphine-stabilized N₂O fragment.

γ-Proton transfer furnished the highly selective title reaction in which cyclic β-haloenals 1 react with β,γ-unsaturated α-ketoesters 2 to generate functionalized spiro-3,4-dihydro-2H-pyrans 3 having an α-quaternary carbon center and an adjacent vinyl halide group in skeleton. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, Tos=4-toluenesulfonyl.

The ortho-ferration of functionalized arenes using tmp₂Fe⋅2 MgCl₂⋅4 LiCl furnishes the corresponding diorgano Fe^II reagents at 25 °C in high yields. These reagents undergo cross-coupling reactions in the presence of 4-fluorostyrene to give various alkylated arenes. It turned out that Ni^II impurities present in commercial FeCl₂ (98 % pure) catalyzed this alkyl–aryl cross-coupling reaction.

Ring around the roses: The ipso substitution of benzene rings makes a simple and efficient synthesis of pillar[n]arenes (n=5, 6) possible. Pillar[6]arenes (see picture) and pillar[5]quinone, an oxidation product of pillar[5]arene, are novel, highly promising host systems for host–guest chemistry.

Inner workings: Diatom cell walls are outstanding examples of natural hybrid materials and exhibit interesting mechanical and optical properties. Removal of the biosilicates in the cell walls of T. pseudonana with NH₄F proves that the cell walls contain an internal, organic network consisting of crosslinked chitin fibers as well as other organic components (see picture).

Distance learning: Under physiological conditions telomeric sequences adopt different quadruplex topologies, although the exact nature of these species is currently debated. Double spin-labeled oligonucleotides consisting of guanosine-rich telomeric repeats are synthesized and characterized by pulsed EPR techniques. In solution in the presence of K⁺ ions the propeller and basket quadruplex conformations co-exist as a 1:1 mixture.

Look, no hands! Non-supported macroscopic aerogels are fabricated from platinum, gold, and silver, and from bimetallic mixtures of gold/silver and platinum/silver. The hydrogels and aerogels consist of voluminous porous networks of particles or wires that are only a few nanometers thick. These entirely new structures have tremendous potential for applications in catalysis and nanophotonics.

Gold–boron (con)fusion: Addition of an anionic metalloborylene to an [AuCl(N-heterocyclic carbene)] complex results in attack of the boron atom at the gold center and formation of a trimetallic Mn₂AuB framework (see scheme, middle). X-ray structural analysis and DFT calculations show that the bonding situation of this complex cannot be described by the “boryl” (pure boron donor) or “borane” (pure boron acceptor) descriptions.

New wrinkles in folding: In the folding of the D135 ribozyme derived from the group II intron Sc.ai5γ, partial replacement of Mg²⁺ with Ca²⁺ leads to a division into two distinct subpopulations that are not interchangeable. The picture shows the splitting into the two types together with the single-molecule FRET states.

Steps in the right direction: The role of steps in the removal of sulfur from a Pt model catalyst, via metastable SO₃ and SO₄ species, was demonstrated by in situ high-resolution X-ray photoelectron spectroscopy. From isothermal experiments the activation energy of the rate-determining step was deduced to be 34 kJ mol⁻¹.

Cracking up: Use of conventional microscopy allows the width of a crack in a crystal to be determined with an accuracy that is limited by classical diffraction (see picture, left-hand image). Single-molecule imaging methods enable the determination of the crack profile with an accuracy beyond the diffraction limit (right-hand image).