Controlled synthesis based on spectroscopic characterization, structure, and catalytic performance of mesoporous silica SBA‐15‐supported vanadium oxide model catalysts (see TEM image) are reviewed. The effect of water on the structure and dispersion of highly dispersed vanadium oxide is discussed in the light of recent results in multiple in situ spectroscopy.
The Midas touch : The low‐temperature transformation of methanol to methyl formate, formaldehyde, and formic acid is promoted by atomic oxygen adsorbed on metallic gold (see picture). The reactions occur with O‐containing Au nanoparticles formed on Au(111) upon oxidation with ozone at 200 K; the facile esterification to methyl formate occurs well below room temperature.
Everything on a chip : Recent developments in microfluidics enable the combination of droplet microfluidics with continuous‐flow systems (see picture). This is a promising step towards the development of integrated, complex synthesis and analysis laboratories on chips. For example, a building‐block principle could be used to integrate a multistep reaction with purification and analysis.
H bonds make the catalysts! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalysts for asymmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the heterocomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates.
Towards improved kinetic stability : A detailed account of the complexation properties of the ligand 1,4‐bis(hydroxycarbonylmethyl)‐6‐[bis(hydroxycarbonylmethyl)]amino‐6‐methylperhydro‐1,4‐diazepine (AAZTA; see figure) is reported. Its Gd3+ complex shows a kinetic stability superior to that of complexes formed by higher denticity ligands and opens the way for a new reference structure for MRI contrast agents.
A simple but effective copper‐catalyzed borylation of aryl halides, including electron‐rich and sterically hindered aryl bromides, with alkoxy diboron reagents occurs under mild conditions (see scheme). Preliminary DFT studies of the mechanism suggest that σ‐bond metathesis between a copper–boryl intermediate and the aryl halide generates the aryl boronate product.
Enriched cleavage : An efficient chemoselective cysteine modification of unprotected peptides and proteins has been developed by using electron‐deficient alkynes in aqueous media. Interestingly, terminal alkynone‐modified peptides could be converted back into the unmodified peptides by cleavage by adding thiols under mild conditions (see scheme).
Paddle wheels and pillars : Layered 3D metal–organic frameworks comprised of paddle‐wheel coordination units are constructed under a variety of conditions to incorporate bridging ligands (as illustrated) that impart desired properties, such as guest‐exchange behavior, luminescence, microporosity, and stability, to the material.
Functionalized spiroacetals have been easily prepared in a one‐pot three‐component coupling process that involves the reaction of pentynol derivatives, salicylaldehydes, and amines in the presence of catalytic amounts of a palladium(II) complex (see scheme). Alternatively, oxygen‐substituted spiroacetals can be obtained by using orthoesters as the third component.
Sheet‐like mimic enzyme : A novel nanostructure (see figure) of sheet‐like FeS with peroxidase‐like activity was synthesized as a mimic enzyme for the development of amperometric transducers and biocatalysts.
Sensitized photolysis : We describe a series of macrocyclic disulfides containing stiff stilbene (see scheme) as the intramolecular photosensitizer designed for fundamental mechanistic studies of sensitized photolysis of the S? S bond. Preliminary studies revealed weak temperature dependence of the quantum yields, which decreased exponentially with Boltzmann‐weighted average separation between the S? S bond and stiff stilbene.
Let's stick together : The gelation ability of a dendritic gelator has been enhanced by its complexation with a polyelectrolyte (see figure). This concept provides a route to construct novel functional or ordered materials by complexation of other low‐molecular‐mass functional species with polyelectrolytes.
A remarkable twosome : Four‐coordinate square‐planar complexes based on [Zn(salen)] derivatives are conveniently captured inside a crystal matrix using a supramolecular protecting strategy (see figure). The four‐coordinate species is accompanied by a five‐coordinate complex that binds an axial ligand able to hydrogen bond to an N‐heterocycle positioned in the axial region of the coordinative unsaturated derivative. The size of the N‐heterocycle is a decisive stabilization parameter.
Similar, but different : Possessing almost the same but not identical structures, the recently discovered natural products hopeahainol A ( 1 ) and hopeanol ( 2 ) exhibit important but differing biological properties (see structures). Their first total synthesis has now been achieved through a series of novel cascade reactions and skeletal rearrangements.
Water molecules doing time : Atomic‐resolution crystal structures of the PPIase domain of cyclophilin G, alone and in complex with cyclosporin A, and together with MD simulations and calorimetry, reveal how trapped water molecules influence the thermodynamic profile of a protein–ligand interaction.
Economic and practical advantages are offered by the iron(III)‐catalyzed and air‐mediated tandem coupling/hydroarylation/dehydrogenation of simple readily available aldehydes, alkynes, and amines for the synthesis of 2, 4‐disubstituted quinolines (see scheme).
