Domain event: Non-ribosomal peptide synthetases (NRPSs) are gigantic molecular machines which assemble natural products of high structural complexity in bacteria and fungi. A team of researchers has recently solved the first crystal structure of an entire module of domains from an NRPS system, a breakthrough achievement for the field.

A new star is born: First reports on asymmetric cross-coupling reactions of racemic activated and non-activated secondary alkyl halides highlight the particular suitability of nickel catalysts for these reactions. Impressively high enantioselectivities were observed for Negishi, Hiyama, and Suzuki–Miyaura cross-coupling reactions (see scheme). The results can be expected to change retrosynthetic thinking.

Labeling of oligonucleotides is of paramount importance for DNA-based nanotechnology and diagnostic applications. The copper-catalyzed reaction of azides with alkynes is currently revolutionizing the way in which these labeled oligonucleotides are synthesized. TBAF=tetrabutylammoniumfluoride, TIPS=triisopropylsilyl, TMS=trimethylsilyl.

Two sides to the story: Botulinum neurotoxin is among the most lethal species known to man, yet has profound clinical utility. Through the combination of recent structural, biochemical, and biophysical studies, new insights into toxin action have been achieved, leading to a range of small molecules, peptides, and antibodies for treating botulism.

Lucky seven: Crystals of heptacene, which consists of seven linearly fused benzene rings, remain stable for at least 21 days in mineral oil and 24 h in degassed solution when the oligoacene is functionalized with phenyl and triisopropylsilylethynyl groups (see scheme). The right combination of functionalities makes this seven-ring system the most stable functionalized heptacene synthesized to date.

Going for gold! Thymine–Hg²⁺–thymine coordination is used as the basis for a selective assay that detects Hg²⁺ ions with a limit of up to 0.2 parts per billion. The detection is based on the enhancement of fluorescence polarization (FP) by gold nanoparticles (see picture). The overall assay can be carried out at room temperature within only ten minutes, making it suitable for high-throughput routine applications in environment and food samples.

Bound in chains: The molecular Ag⁰ chain [Ag₄py₂]_n (py=C₅H₅N) is formed from two covalently linked infinite zigzag chains of Ag, in which AgAg bonds alternate between long and short (see picture; blue Ag, gray C, orange N). Theoretical calculations indicate that partially positively (+0.35) and negatively (−0.30) charged Ag atoms are alternately located along the chain, which has a bandgap of 4.1 eV.

Nanotube detects isomers: A chemiresistive material based on carbon nanotubes wrapped with a calixarene-substituted polythiophene displays a selective and sensitive response to xylene isomers (see picture), as demonstrated by conductance changes, quartz crystal microbalance, and fluorescence studies. This demonstrates the promise of low-cost, real-time sensors utilizing host–guest chemistry.

Zeolitic jelly-donuts: Micron-sized cubes of zeolite A having a monocrystalline shell and an amorphous core were synthesized by in situ crystallization of sodium aluminosilicate gel in uncrosslinked chitosan hydrogel. Formation of cubelike core–shell structures involves particle aggregation and surface-to-core crystallization induced by the hydrogel network, and provides a new model for zeolite nucleation and growth mechanisms.

Pores for thought: The formation of nanostructured TiO₂ films is templated by dendritic amphiphilic core–double-shell macromolecules. The templates consist of a hydrophobic polystyrene (PS) interior and a hydrophilic poly(acrylic acid) (PA) exterior (see picture). The pore size of the films can be controlled by adjusting the length of the hydrophobic block in the inner shell of the macromolecules.

F⁻ on: The title compound TBAF(tBuOH)₄ can act as a highly effective fluoride source for nucleophilic fluorination thanks to its favorable properties, such as a stable structure (in which the fluoride ion is surrounded by four bulky nonpolar protic alcohol molecules), a dehydrated state, low hygroscopicity, good solubility in organic solvents, good nucleophilicity, and low basicity.

A color-changed sandwich: A novel water-soluble cyclophane containing anthracene and imidazolium moieties (see structure) exhibits dual emission in aqueous medium and undergoes sequence-selective interactions with DNA but not with proteins and micelles. In the presence of DNA, it forms a sandwich-type excimer, which exhibits an unusually long lifetime (τ) and red-shifted emission. This cyclophane can be used for DNA recognition through “turned on” excimer emission.

Controlled patterning of highly oriented pyrolitic graphite with well-defined 3D nanostructures is realized by steered uniaxial alignment of multilayered [2.2]paracyclophane-based building blocks bearing functional clips (see picture). Their in-plane self-assembly allows exact positioning of vertical structural elements with precisely defined nanoscale spacing.

No sweat PET: Controlled axial coordination of pseudo-square-planar zinc(II) complexes to 4-(dimethylamino)pyridine-functionalized polystyrene resin facilitates the synthesis (by transmetalation) and purification (by selective ligation) of metallo-radiopharmaceuticals. These complexes have potential as positron emission tomography (PET) imaging agents.

Finding the missing species: Two isopolyoxotungstate clusters with unprecedented “S”-shaped [H₄W₂₂O₇₄]¹²⁻ and “§”-shaped [H₁₀W₃₄O₁₁₆]¹⁸⁻ geometries are presented. The development of this structural complexity comes from the structural evolution based on the {W₁₁} fragment and establishes a new building block principle in isopolyoxotungstate chemistry. The evolved clusters can only be isolated in the presence of sulfite ions.

Humpty Dumpty, heal thyself: Four fragments of a catalytic RNA can autocatalytically self-assemble back into a covalently contiguous ribozyme. This reaction network (see picture) demonstrates anabolic autocatalysis in which positive feedback occurs at multiple points.

Helices on demand: Collagen peptides were engineered to form triple helices under environmental control. The replacement of the hydroxyproline (Hyp) residues in a collagen peptide with carboxylate-modified Hyp residues gave a petide that forms a collagen triple-helical structure at acidic pH values and low temperatures and adopts a monomeric, polyproline II helical conformation under neutral conditions (see scheme).

Reduce, reuse, recycle: A new methodology allows the synthesis of ordered mesoporous materials in water at room temperature, eliminating the need for organic solvents and reducing the amount of energy consumed. It relies on the reversible formation of micelles of water-soluble block copolymers as structure-directing agents (see picture). After recovery of the mesoporous material, the reaction solution can be used again.

Magnetic, fluorescent core–shell nanoparticles consist of a single Fe₃O₄ nanocrystal core and a dye-doped mesoporous silica shell with a poly(ethylene glycol) coating (see picture of TEM images and schematic depictions). These nanoparticles can be used as magnetic resonance and fluorescence imaging agents, and as drug delivery vehicles, thus making them novel candidates for simultaneous cancer diagnosis and therapy.

Surface safari: 9,10-Anthracenedicarbonitrile (DCA) molecules adsorbed on a Cu(111) surface can be titrated by gradual annealing of the substrate to form trigonal planar Cu(DCA)₃ complexes and, ultimately, a hexagonal network (see picture) with a Cu₂(DCA)₃ stoichiometry. As a result of charge donation from the substrate, the coordinated Cu adatom remains electrically neutral despite donating approximately 1/3 charge to each CuN bond.

Better off med: The assembly of eight-coordinate indium molecular building blocks (MBBs) and 4,5-imidazoledicarboxylate (Himdc) ligands in the presence of a structure-directing agent results in the formation a novel 4-connected zeolite-like metal–organic framework (ZMOF) with an unprecedented zeolite topology (med topology, see picture; In green, C gray, N blue, O red; the framework topology of usf-ZMOF is shown in green tetrahedra).

A subtle difference: A single step suffices to transform a linear precursor into the chromane spiroketal core of the metalloproteinase-3 inhibitor berkelic acid by an acid-catalyzed deprotection/Michael addition/acetalization cascade. This efficient route resulted from the realization that the originally proposed structure is neither thermodynamically nor kinetically favored and has led to revision of the structure (denoted in red).

Box it up! Self-assembly of 5,10,15,20-tetrakis(4-pyridyl)porphyrin with two equivalents of cis-[(dppf)Pt(OTf)₂] (dppf=1,1′-bis(diphenylphosphino)ferrocene; OTf=CF₃SO₃⁻) yielded the first open molecular box containing six porphyrin walls (see scheme) and an internal open void volume of around 43 550 ų.

Surprisingly cis-tematic! The cobalt(II) complex of a D₂-symmetric chiral porphyrin is an effective catalyst for asymmetric cyclopropanation with α-nitrodiazoacetates (see scheme). The catalytic system is general and suitable for electron-sufficient, -neutral, and -deficient alkenes, forming the corresponding cyclopropane nitroesters in high yields. In addition to high diastereo- and enantioselectivity, the catalytic process exhibits atypical Z selectivity.

Liquid assets: The catalyst (S,S)-1 exhibits an unprecedented reactivity and excellent enantioselectivity for the title reaction when it is carried out in neat ionic liquid (see scheme; BMIM=1-n-butyl-3-methylimidazolium, Tf=trifluoromethanesulfonyl, Ts=4-toluenesulfonyl). The ionic liquid facilitates the catalyst recycling and enhances its stability and selectivity.

Domino theory: A simple, highly enantioselective organocatalytic aminosulfenylation of α,β-unsaturated aldehydes affords orthogonally protected β-amino-α-mercaptoaldehydes in high yields and 93 to >99 % ee (see scheme, Bn=benzyl). Notably, the catalytic transformation shows that it is possible to efficiently employ all components of an electrophile, which includes a nucleofuge, in organocatalytic domino reactions of enals.

Get a grip: Measurement of receptor adhesion strength requires the precise manipulation of single cells on a contact surface. To attach live cells to a moveable probe, DNA sequences complementary to strands displayed on the plasma membrane are introduced onto AFM cantilevers (see picture, bp=base pairs). The strength of the resulting linkages can be tuned by varying the length of DNA strands, allowing for controlled transport of the cells.

Pores for thought: Noble-metal catalysts supported on mesoporous zeolites have been found to be much more efficient than on microporous zeolites and γ-Al₂O₃ for the hydrodesulfurization of 4,6-dimethyldibenzothiophene (DMDBT, see picture). This increased efficiency arises because the relatively large DMBT molecules can fit into the relatively large pores of the mesoporous zeolites and so reach many active centers.

Playing tag with MOFs: Zinc metal–organic frameworks with pendant aldehyde and methoxy groups are prepared. The aldehyde-tagged MOF takes up 2,4-dinitrophenylhydrazine, reacting to form a hydrazone-functionalized MOF which is crystallographically characterized. Use of both aldehyde- and methoxy-functionalized dicarboxylates leads to MOFs containing both ligands, of which the aldehyde groups can be selectively reacted.

Use the Force: A force field for the MIL-53(Cr) framework was derived and validated by molecular dynamics simulations. This approach allows the “breathing” of the framework in the presence of CO₂ to be captured and gives insight into the structural switching mechanism from a narrow- to a large-pore form (see picture). This force field can be used directly in studies of many guest molecules and, with a minimum adjustment, for other MOF systems.

Enamides made easy: A catalyst system generated in situ using bis(2-methallyl)(cycloocta-1,5-diene)ruthenium(II), 1,4-bis(dicyclohexylphosphino)butane, and ytterbium triflate efficiently catalyzes the addition of primary amides to terminal alkynes, selectively forming the Z-anti-Markovnikov enamides. The E isomers are also accessible by combining the hydroamidation with an in situ double-bond isomerization reaction.

Complete control: A highly efficient, copper-catalyzed, asymmetric carbenoid insertion into SiH bonds, using chiral spiro diimine (SIDIM) ligands (see scheme, Ar=2,6-Cl₂C₆H₃, OTf=trifluoromethanesulfonate), produces a wide range of α-silylesters, in high yields with excellent enantiomeric excesses. This catalytic system offers unprecedented levels of enantiocontrol for the SiH bond insertion reaction.

An ocean of possibilities: Aburatubolactam A, a natural product isolated from the culture broth of a marine mollusk, was the target of a total synthesis (see scheme). Key transformations include tandem ring-opening/ring-closing metathesis, Lacey–Dieckmann cyclization, and macrolactamization.

Don't blink or you'll miss it: A transient imidoscandium complex (see scheme) can be generated by several routes. The imido ligand can activate the CH bond in pyridine and benzene, and it can be complexed with Al(CH₃)₃ to yield an imide zwitterion. A combination of isotopic labeling, reactivity, and theoretical studies strongly endorse formation of a terminal imido ligand at scandium.

Living cells can be coated with continuous oxide shells prepared from modified titanium alkoxides (see picture). The shells efficiently isolate the encapsulated biomaterial from the surrounding medium. The resulting colloid media are highly biocompatible; subsequent release (biodelivery) of encapsulated cells or drugs is possible by dissolution of the titania nanoparticles.

Nickel saves dimes: The expense of using precious-metal catalysts is avoided in the high-yielding conversion of cellulose to ethylene glycol (see picture; AC=activated carbon). This process occurs in up to 29 % yield over a tungsten carbide catalyst, and in up to 61 % yield when the catalyst is promoted with a small amount of nickel. An attractive feature of this reaction is the low yields of other polyols with respect to ethylene glycol.

Getting to the center of it: The strategy for an efficient asymmetric synthesis of the D-ring subunit embedded in massadine (1) includes: application of a cationic norbornyl rearrangement, ozonolytic cleavage displaying remarkable end-group differentiation, and a carboxy-inversion reaction for the installation of the hindered secondary alcohol.

Making the cut: Electrons at energies close to 0 eV have been shown to be resonantly captured by gas-phase D-ribose-5-phosphate (a model compound for the DNA and RNA backbone) with subsequent cleavage of the sugar–phosphate linkage (see scheme). This supports the idea that breakage of DNA strands by electrons at very low energies are triggered by dissociative electron attachment directly to the DNA/RNA backbone.

A Val-uable link: The title transformation is achieved by a two-step ligation, radical-based desulfurization strategy (see scheme; NCL=native chemical ligation). After S→N acyl transfer, in which the acyl acceptor is a γ-thiol valine derivative, and site-specific dethiolation, a valine residue appears at the site of ligation. This method accomplishes ligations at Thr-Val and Pro-Val sites, and allows successful ligation of glycopeptide fragments.

Watching crystals grow: In situ atomic force microscopy has been used to observe the crystal growth of the nanoporous metal–organic framework HKUST-1. This real-time study provides evidence that the growth of HKUST-1 under the given supersaturation conditions is through a surface nucleation mechanism and presents insight into the units of attachment during the growth of the 1.5 nm high steps on the crystal surface (see picture).