Angewandte Chemie International Edition

Sunlight does chemistry in nanohybrids composed of CdS quantum dots (QDs) and enzyme P450_BSβ. The hybrids, which are self-assembled through electrostatic interactions between the negatively charged QDs and the positively charged His₆-marked P450, produce hydroxyl and superoxide radicals upon irradiation. In their Communication on page 504 ff., B. I. Ipe and C. M. Niemeyer report that these reactive oxygen species activate P450 to catalyze the monooxygenation of myristic acid. (Graphic prepared by P. Alhorn, B. Ipe, and K. Rabe.)

A wide variety of optically active compounds as well as active compounds such as amino acid derivatives can be accessed by the cross-Mannich reaction of aldehydes, particularly by the direct catalytic asymmetric version, in which CC bonds are formed. Remarkable advancements have been reported, including one-pot, three-component procedures with absolute stereocontrol and high yields (see example, NMP=N-methylpyrrolidine).

Conjugate additions lead the way in catalytic asymmetric tandem transformations, which allow rapid access to complex molecular structures from readily available starting compounds. The advantage of such transformations is the formation of several bonds and the creation of two or more contiguous stereogenic centers by using a single catalyst in one pot (see scheme).

Man-made atoms: Experimental techniques, such as hot fusion (see scheme) and theoretical calculations on the superheavy elements (the transactinides) are now shedding light on the chemistry of these elements. Nuclear chemistry, performed at the ultimate one-atom-at-a-time limit, has reached element 108, hassium, and the elements 112 and beyond are now under investigation.

Structural changes that occur at the palladium(111)/water interface during the electrocatalytic oxidation and reduction of water (see picture) have been calculated by ab initio methods. These results have been used to construct an electrochemical phase diagram, and demonstrate the influence of the polarization of the water/metal interface on surface properties.

Bond formation between single Pt atoms and surface thiol groups is the result of the reduction of a Pt precursor in the presence of surface-thiolated carbon nanotubes. By setting the temperature of the following heat treatment, finely size-controlled and monodispersed Pt clusters were obtained from the dispersed single atoms (see picture).

The probable reaction pathways for propylene epoxidation with O₂ and H₂ in the presence of trimethylamine on trimethylsilylated Au-Ba(NO₃)₂/titanosilicate catalyst are discussed (see figure). The use of trimethylamine as a gas-phase promoter for nanoparticulate gold catalysts leads to a direct one-stage production of propylene oxide (PO) with steady space–time yields comparable to values for current industrial ethylene oxide production.

Proton relay in cyclic 7-hydroxyquinoline–(alcohol)₂ complexes (see picture) has been explored in nonpolar solvents. The asymmetric triple proton transfer has an unusually large, temperature-independent, and viscosity-dependent kinetic isotope effect. Heavy-atom motions (wavy arrow) of solvent and bridging molecules allow proton tunneling by assisting the complex to reach the optimal precursor configuration.

Bring in the substitute! Zn_1−xCo_xO nanowires are prepared by using a solution-based synthetic route. Structural, optical, and spectroscopic characterizations indicate that the cobalt atoms substitute the zinc cations in the host lattice as a result of the cobalt doping (the picture shows prepared Co-doped ZnO nanowires).

An alternative route: The fungal metabolite FR235222, a potent inhibitor of mammalian histone deacetylase (HDAC), has been synthesized. Key steps are the preparation of unusual amino acids Ahoda and (2R,4S)-MePro. A 3D model for cyclopeptide inhibitor interaction with the HDAC active site (see picture) highlights the differences between the binding mode of small-molecule and cyclopeptide inhibitors.

Speed up: In situ formation of perovskite phases (Ca_δTiO_x, x/δ≥2) during electroreduction of porous TiO₂ pellets to Ti metal in molten CaCl₂ kinetically retards the process. Ex situ perovskitization of TiO₂ with CaO (see picture) can prevent in situ perovskitization during electrolysis, thereby significantly increasing the electroreduction speed.

Giant clusters: Metal-assisted hydrolysis of 2,6-bis(2-pyridylcarbonyl)pyridine with Co(O₂CMe)₂⋅4 H₂O in hot DMF yielded an icosanuclear Co^II complex containing the triply deprotonated bis(gem-diol) form of the ligand and exhibiting superparamagnetic relaxation of its magnetization. The picture shows the central Co–O core of the complex (Co violet, O red).

Complementary electronic properties of inorganic and organic halogen species are exploited in the design of molecular networks that employ MX⋅⋅⋅X′C halogen bonds. The dominance of electrostatic effects in this type of interaction over other energy terms, such as charge transfer, is demonstrated by the study of a series of eight isostructural compounds (4-X′pyH)₂[CoX₄] (see picture; X=Cl, Cl/Br, Br, I; X′=Cl, Br).

The additional molecule of methyllithium present in [(Me₄Fe)(MeLi)][Li(OEt₂)]₂ (1), the first structurally characterized ate complex of Fe^II bearing only alkyl substituents without any further stabilizing ligands (see picture: Fe: magenta; Li: cyan; O: red; C and H: gray), is a particularly remarkable structural feature and contributes to the fascinating reactivity profile of 1 in the title reactions.

Hot air in a hurry: An industrial Fe-Mo-O catalyst, used in the production of formaldehyde has been studied under redox conditions using rapid in situ powder diffraction studies (see contour image). Surprisingly, the oxidation step is fastest as it is completed within 15 s at 472 °C.

Remarkable selectivity (88 % in the steady-state reaction and 94 % in the pulse reaction) is observed in the direct synthesis of phenol from benzene with molecular oxygen over a Re/zeolite catalyst prepared by chemical-vapor deposition. The novel interstitial-N/Re clusters are formed with NH₃ and are essential for the activity in the selective oxidation reaction.

Hidden qualities: [Rh(PiPr₃)(C₁₄H₁₆)][BAr^F₄] (1; see picture of the cation; P violet, Rh olive green), which was synthesized by treatment of [RhCl(nbd)(PiPr₃)] with Na[BAr^F₄] (BAr^F₄=B{C₆H₃(CF₃)₂}₄) and norbornadiene (nbd) in fluorobenzene, contains an organic fragment derived from Binor-S as well as agostic Rh⋅⋅⋅CC and Rh⋅⋅⋅HC interactions. In solution, 1 undergoes rapid, reversible CC activation/reductive elimination.

Good cholesterol: Oligo(p-phenylenevinylene)s (OPVs) that are mono- or disubstituted with cholesterol moieties form pseudo-J and pseudo-H aggregates, respectively (see picture), which lead to coiled and twisted helical structures with distinct optical, chiroptical, and morphological properties.

Artificial cells: A polyoxomolybdate capsule, in which the cavity is linked to surface pores by channels, can take up Pr³⁺ ions. Each uptake reduces the negative charge on the capsule so that eventually no more Pr³⁺ ions enter the capsule, instead they remain bound on the surface (see structure: external hydrated Pr³⁺ green polyhedra, encapsulated Pr³⁺ light green, Mo blue, O red, SO₄²⁻ yellow). This process models voltage gating of the ion channels of cells.

From A to Z: Allylzirconocenes have been easily prepared in a one-pot procedure through a tandem allylic CH activation–β-elimination reaction from unsaturated fatty alcohol and ether starting materials (see scheme). The reaction proceeds rapidly under mild condition and is insensitive to the length of the carbon tether between the double bond and the alcohol moiety.

Protection strategy: Glycosylphosphatidylinositols (GPIs) from the Trypanosoma cruzi parasite (a causative agent of Chagas' disease) that contain an unsaturated fatty acid in the lipid moiety (see partial structure of 1, R=(CH₂)₇CHCH(CH₂)₇CH₃, and 2, R=(CH₂)₇CHCHCH₂CHCH(CH₂)₄CH₃) were prepared by a strategy that employs non-benzyl-type protecting groups. The synthetic GPIs show similar biological activity to their natural counterparts.

A new synthesis of iridabenzene species involves the coupling of MeCHCH₂ with iridacycles 1 and 2. Surprisingly, the structure of the coupling product of the iridacyclopentadienes with propene (3 or 4) is highly susceptible to the nature of the substituents in the starting metallacycle.

Anchored down: Long lipopeptides (up to 26 amino acids) that carry multiple sensitive lipid residues as well as different reporter groups and tags can be synthesized efficiently by employing the Ellman sulfonamide linker as an anchoring group to the solid support (SPPS=solid-phase peptide synthesis).

Just the one: The combination of palladium dichloride and N,N-dimethylacetamide (DMA) constitutes a highly efficient and reusable catalytic system, which uses molecular oxygen as the sole reoxidant for liquid-phase Wacker oxidation and acetoxylation of terminal olefins to the corresponding methyl ketones and linear allylic acetates, respectively (see scheme).

Broken bonds: The reaction of [(Cp*Ru)₃(μ-H)₃(μ₃-H)₂] (1, Cp*=η⁵-C₅Me₅) with an equimolar amount of benzonitrile yields the μ₃-nitrido-μ₃-allyl complex 2 as a result of the CN bond cleavage (see scheme). The CN bond cleavage proceeds through the formation of μ₃(⊥)-iminoacyl complex [(Cp*Ru)₃(μ₃-η²:η²(⊥)-PhCNH)(μ-H)₂].

Blocking the way: Substitution at the 2-position in pyridines and other N-heterocycles blocks N-coordination to an Ir center. This steric hindrance provides a substrate-design criterion that allows the Ir-catalyzed borylation of CH bonds, which can be followed by Suzuki–Miyaura cross-coupling in a one-pot reaction (see scheme; B₂pin₂=bis(pinacolato-O,O′)diboron, dtbpy=4,4′-tBu₂-2,2′-bipyridine).

The famous five: The elusive five-coordinate nitrito complexes [Fe^III(por)(ONO)] (por=meso-tetraphenylporphyrinato dianion or meso-tetra-p-tolylporphyrinato dianion) have been obtained by interaction of low-pressure NO₂ with sublimed layers of [Fe^II(por)]. Spectral data confirm that the NO₂⁻ ligand prefers to bind through O coordination but adopts the N-bonded configuration when the second axial site is occupied (R=Ph, p-tolyl).

Easy-to-prepare solutions of LnCl₃⋅2 LiCl (Ln=La, Ce, Nd) (0.3–0.5 M in THF) are a unique source of soluble lanthanide salts with versatile applications in organic synthesis. These salts can serve as promoters or catalysts for the addition of organometallic compounds to sterically hindered, enolizable or α,β-unsaturated ketones or imines.

Predictable ion selectivity is a major goal for the use of synthetic channels in biological systems. Gramicidin A (gA) is a suitable lead structure for the design of such channels. The crown ether–gA hybrid structure shown forms ion channels with a higher ion selectivity for K⁺ than for Cs⁺.

Synthesis with light: CdS quantum dots (QDs) generate superoxide and hydroxyl radicals upon UV irradiation in aqueous solution. The radicals are used for activating P450_BSβ enzymes attached at the QD surface, effecting the catalytic transformation of myristic acid into α- and β-hydroxymyristic acid (see picture, R=(CH₂)₁₀CH₃).

Watching live: The FRET reporter PENN/SATE (see picture; FRET=fluorescence resonance energy transfer) is membrane permeant and enters cells and small organisms by using a prodrug approach. Once inside cells the reporter is cleaved by phospholipases, which results in a 30-fold change in the emission ratio