A gigantic polyoxometalate …︁…︁ [Ce₂₀Ge₁₀W₁₀₀O₃₇₆(OH)₄(H₂O)₃₀]⁵⁶⁻ (1) was obtained in a classic one-pot synthesis from Ce^III ions and the trilacunary precursor [α-GeW₉O₃₄]¹⁰⁻ in water, as described by U. Kortz and co-workers in their Communication on page 6192 ff. The cover picture shows a possible mechanism of formation by stepwise self-assembly, beginning with the formation of Ce₂GeW₁₀ Keggin units, followed by arrangement of five such units into chiral, enantiomeric {Ce₂GeW₁₀}₅ species, and then dimerization of the R and S forms to give 1.

Chain-walking isomerization of the growing polymer end occurs during the cyclopolymerization of 1,6-dienes catalyzed by Pd^II complexes, and leads to polymers with trans-1,2-disubstituted cyclopentane rings and polar functional groups located regularly along the linear polymer chain, as described by K. Osakada and co-workers in their Communication on page 6141 ff.

Threading nanobeads: Gold nanoparticles (NPs) coated with functional organic ligands are candidate building blocks for the bottom-up fabrication of nanostructured materials. This Highlight describes a recent approach to achieving bidirectional NP–NP connectivity, which is an essential step in the assembly of NP-based polymers (see scheme) and more complex nanoarchitectures.

A double jubilee: This year marks the 50th anniversary of the discovery of the Asinger reaction—the original version a three-component reaction for the direct synthesis of thiazolines from elemental sulfur, ammonia, and a carbonyl component—and the centennial anniversary of the birth of its eponym, Friedrich Asinger (1907–1999).

Combinatorial discovery: High-throughput techniques are already used routinely for research on complex materials, such as polymers, electronic materials, and catalysts. Remarkable achievements are related to parallel syntheses and analyses, data-mining technologies, modeling approaches, as well as evolutionary strategies for materials development and formulations. The discoveries and success stories document the power of these emerging technologies.

The path less taken: Copolymerization of imines and carbon monoxide has long been highly desirable as a route to synthesize polypeptides, but has been difficult to implement because of the lack of appropriate catalysts. This reaction has now been realized for the first time by using a simple cobalt catalyst (see scheme).

Nonnatural interactions: The X-ray crystal structure of a mutant aminoacyl-tRNA synthetase that selectively recognizes para-benozyl-L-phenylalanine has been solved. This structure shows that mutations to the enzyme lead to new hydrophobic binding interactions with the unnatural amino acid, and a loss of specific hydrogen-bonding interactions with tyrosine, without a significant change in the polypeptide backbone conformation.

Star formation: Polymeric [Fe₃(μ₃-O)(μ-OAc)₆(H₂O)₃][Fe₃(μ₃-O)μ-OAc)_7.5]₂⋅7 H₂O is synthesized by linking triangular {Fe₃(μ₃-O)} clusters through anti-anti bridging acetate ligands (see picture; red and blue: Fe, orange: O). Spin frustration and long-range magnetic order coexist in this compound below 4.5 K (see graph).

One-dimensional polymer [Tb(pzam)₃(H₂O)Mo(CN)₈]⋅H₂O (see picture, pzam=pyrazine-2-carboxamide; C black, Mo yellow, N blue, O red, Tb green) has been synthesized and characterized. Its magnetic susceptibility data indicate substantial ferromagnetic superexchange between Tb^III and Mo^V via the cyanido bridge, and the occurrence of long-range magnetic ordering between chains at T_c≈1 K.

Take your PIC: Biologically active polyion complex vesicles (PICsomes) with encapsulated myoglobin (Mb) can be prepared by the self-assembly of a pair of oppositely charged block ionomers with polyethylene glycol (PEG) segments (see picture; metMb: metmyoglobin). The loaded Mb maintains reversible oxygenation even in the presence of trypsin.

Meeting in the middle: Well-organized arrays of self-assembled functional DNA nanotubes can be constructed by combining bottom-up and top-down methods. Such DNA-nanotube arrays allow the construction of arrays of quantum dots, proteins, and DNA targets (see picture; green: DNA nanotube, red: streptavidin–quantum dot conjugate; scale bar: 20 μm).

Completely armless: The efficient synthesis of two sterically confined [2]rotaxanes has shown that oligoethylene glycol arms are not requisites for a clipping reaction to form π-donor/acceptor [2]rotaxanes (see scheme). The rigid nature of the [2]rotaxanes forces the tetracationic cyclophane to encapsulate the initially π-electron-rich station, regardless of its oxidation state, thus generating tunable properties and enhanced stabilities.

Potential causes: The combination of potential-pulse perturbation and STM has shown that the interfacial oxidation of an adsorbed 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) monolayer at the Au(111)/0.1 M H₂SO₄ interface is spacially heterogeneous (see STM image; dark spots: oxidized TPyP, light spots: nonoxidized TPyP). The distribution of the oxidized TPyP molecules on the surface depends on the oxidation potential and varies with time.

Escape! Electronic-structure calculations have been used to estimate the energy barriers to the migration of H₂ guest molecules from the cages of the structure-II clathrate hydrate (see picture; H green, O red). The escape rates from the cages were calculated using an Arrhenius expression with a tunneling correction.

Stuck in the middle with you: The spherical cluster {(Mo)Mo₅}₁₂Cr₃₀ (1) fills, with its spin, a gap in the series of the analogous Fe (S=5/2) and V (S=1/2) clusters. This allows a deeper understanding of the magnetic properties of the series members, particularly with reference to geometric frustration, also found in the famous Kagomé lattices. The spherical clusters can be considered as coordination polymers with spherical periodicity which contain unique pentagonal molybdenum oxide based ligands.

It's elemental: A water-soluble polymer bearing multiple metal-chelating ligands has been used as a tag for bioassays with inductively coupled plasma mass spectrometry. The tag was covalently conjugated to antibodies, and the polymer–antibody constructs were loaded with lanthanide ions (Ln³⁺) and used for the simultaneous assay of five orthogonally labeled antibodies against cell surface antigens that differ in abundance by more than two orders of magnitude.

Stretchable diamond nets: Homochiral and achiral diamond nets with nearly identical unit cells have been found in a family of 3D framework materials containing flexible helical substructures (see picture; Cd green, O red, C gray). Such structures raise intriguing prospects for developing general strategies for the direct conversion of achiral four-connected networks into homochiral networks through ligand substitution.

On its own: A vanadium(II) bis(pyrrolide) complex with a vanadocene-type structure is a single-component catalyst for the preparation of ultrahigh molecular weight polyethylene (PE; see scheme; M_w=weight-average molecular weight, PDI=polydispersity index).

An atom-economical method has been developed for the preparation of chiral vicinal diamines through a dynamic kinetic asymmetric allylic amination and acyl-group migration of vinyl aziridines with imido carboxylates. Application of the asymmetric transformation enabled the concise synthesis of the azepane core 1 of (+)-balanol and its syn analogue.

Hitting the target: Self-assembled polymeric nanoparticles from an amphiphilic copolymer were prepared with furan groups on the outer polyethylene glycol corona that were accessible for Diels–Alder reactions with maleimide-functionalized antibodies for the preparation of immuno-nanoparticles (see picture). The simple and clean coupling methodology allows facile modification of nanoparticles for use in targeted delivery to cancer cells.

Magnetic personalities: [Fe(η⁴-C₁₄H₁₀)₂]⁻ is an unprecedented example of an anionic 17-electron homoleptic polyarene transition-metal complex. This species is the first isolable homoleptic polyarene iron complex. It provides “naked” atomic Fe^−I in its reaction with 1,3-butadiene to yield the first structurally authenticated homoleptic bis(1,3-butadiene) metal complex, [Fe(η⁴-C₄H₆)₂]⁻ (see structure).

Binary encoding and amplification can be achieved in linear polypeptide-based scaffolds of photoactive dithiane adducts. QA masked sensitizer is tethered to lysine and incorporated in a peptide chain terminated with a sensitizer (see picture). When illuminated, the sensitizer induces fragmentation, thus unmasking more sensitizer and resulting in a linear domino photoamplification effect.

Walk the line: Cyclopolymerization of 1,6-dienes with vinyl and vinylene groups catalyzed by Pd^II–diimine complexes causes chain walking of the growing polymer. This isomerization leads to polymers with trans-1,2-disubstituted cyclopentane groups located regularly along the linear polymer chain (see scheme). The polymerization is applicable for dienes with various functional groups.

On the rack: Splitting of the peripheral metal-based oxidation, which indicates a large coupling between the redox sites, has been obtained in polymetallic arrays composed of rack-type complexes containing two, three, four, or six Ru^II subunits appended to hydrazone-based molecular strands (see picture). The relatively small coupling attenuation parameter calculated for the metal-based, cationic subunit(s) suggests molecular-wire behavior.

Upon careful tuning of the reactivity of glycosyl donors and acceptors, tetra- and hexasaccharide fragments (see structure) of the B chain of rhamnogalacturonan II (RGII) were prepared in a convergent and stereoselective manner. The conformation of the central arabinopyranosyl ring (red) was found to depend on the saccharide substitution pattern. This conformational epitope may influence the biological functions of RGII.

Chemists are closing in on functional and structural models for the [FeFe] hydrogenases. Oxidation of [Fe₂(S₂C₂H₄)(CO)₃(PMe₃)(dppv)] (dppv=cis-1,2-C₂H₂(PPh₂)₂) by one electron affords a mixed-valence model for the H_ox state of the active site of the [FeFe] hydrogenases. Like the enzyme, this model exhibits the “rotated structure” and binds CO (see scheme). The radical character of the model is confirmed by its ready binding of NO.

From chimera to useful reagent: Easy access to trifluoromethanol in a one-step reaction from readily available inexpensive bulk chemicals opens the door for CF₃OH to become a useful general reagent in synthetic chemistry and industrial applications.

Three in one: Three new rings can be made in one pot with complete control of the regio- and stereochemistry by a tandem cyclization/cycloaddition cascade reaction. Treatment of a chloroaldehyde with an amine gives a cyclic azomethine ylide that undergoes intramolecular cycloaddition onto a tethered alkene. The method was applied to the shortest known synthesis of aspidospermine (see scheme).

Bridging the gap between a binary system and a solute in aqueous solution: Conformers of the ternary cluster propylene oxide (PO)⋅⋅⋅(H₂O)₂ were studied using rotational spectroscopy and high-level ab initio calculations. The experimental observation shows that the anti conformer is favored over the syn conformer, opposite to what was detected for PO⋅⋅⋅H₂O, but in accord with what was predicted for PO in water.

Actin class: A stereoselective synthesis of the microfilament-destabilizing cytotoxic macrolide (−)-reidispongiolide A, isolated from the marine sponge Reidispongia coerulea, uses a convergent aldol-based strategy to construct the 26-membered macrolactone, followed by a coupling with an N-vinylformamide subunit. This constitutes the first synthesis of any member of the reidispongiolide/sphinxolide family.

Biscyclopropanation: Dienynes containing a cyclohexadienyl unit can be converted into tetracyclo[3.3.0.0^2,8.0^4,6]octanes by treatment with an (N-heterocyclic carbene)gold catalyst. When the dienynes bear an open-chain diene instead of cyclohexadiene, open-cage compounds, with two sides missing from the cage, are obtained.

What makes a good organocatalyst? DABCO (1,4-diazabicyclo[2.2.2]octane) is a thousandfold better nucleophile (k_→) and at the same time a million times better leaving group (k_←) than DMAP (4-(dimethylamino)pyridine). This apparent contradiction is resolved by consideration of the intrinsic reaction barriers.

Let loose in the red-light district: “Caged” DNAs are described that can be activated by light of selectable wavelength. This is possible with, for example, red light, which is significantly less damaging than UV light and can permeate deeply into tissues (see scheme).

A tale of the unexpected: Coordinating and potentially chelating groups allow gold-catalyzed benzylic CH activation at room temperature. Substrates with additional nucleophilic substituents undergo unexpected dimerizations, in which eight new bonds are formed (see scheme).

To catch a bug: Self-assembly of bacteria has been achieved by combining Escherichia coli and synthetic zeolite L. The assembly can be controlled so that the structure possesses either a 1:1 or 2:1 ratio (see schematic representation) between the bacteria and porous nanocontainers.

Big W: One of the largest polytungstates, the 20 cerium(III) atom tungstogermanate [Ce₂₀Ge₁₀W₁₀₀O₃₇₆(OH)₄(H₂O)₃₀]⁵⁶⁻ (1), has been synthesized from Ce^III ions and [α-GeW₉O₃₄]¹⁰⁻ in aqueous acidic medium at pH 5.0. Polyanion 1 represents the first lanthanide-substituted tungstogermanate and can be described as a dimer that is linked through long CeO(W) bridges.