Size matters: Nanometer‐sized gaps in aggregates of silver nanoparticles are generated by covering the nanoparticle surface with a bilayer of cetyltrimethylammonium bromide. The nanometer‐ to micrometer‐sized wells are lithographically generated on polydimethylsiloxane surfaces. The wells filled with the modified nanoparticles (see picture) and the effect of the aggregate size on SERS enhancement are investigated.
InBr 3 promotes the addition of ketene silyl acetals to monosubstituted alkynes to afford 2,2‐disubstituted alkenylindium compounds in high regio‐ and stereoselectivity (see scheme). In addition, the alkenylindium derivatives have been subsequently coupled with iodobenzene in the presence of a palladium catalyst.
Round and round : Covalently bound spokes induce an efficient template‐directed cyclization towards a rigid molecular wheel (see figure) and afford dramatically increased shape‐persistence properties compared with non‐strutted macrocycles.
Bridged Ca 2+ ???CO???Ca 2+ complexes are formed on dual‐cation sites, constituted by a pair of nearby Ca2+ cations, when CO is adsorbed on zeolite Ca‐A. Two types of such species can be formed, designated S2–S1 and S1–S1 (see picture). Ca2+???CO monocarbonyl species are also identified, and at a relatively high CO equilibrium pressure, dicarbonyl complexes can also form.
Aryl–alkyl cross‐coupling products are obtained by the iron‐catalyzed oxidative heterocoupling of organozinc reagents under mild conditions. This novel reaction pathway is versatile, allowing for the use of primary and secondary aliphatic diorganozinc reagents as coupling partners as well as tolerating functionalized aryl‐ and alkylzinc reagents.
′I′ is all the hype : A twofold excess of iodoarene in the title reaction leads to ortho‐quinols in good yields, whereas organocatalytic versions of this reaction enable subsequent epoxidation in a regio‐ and diastereoselective fashion. Chiral iodobiarenes led to enantioselectivities up to 50 % ee. m‐CPBA=meta‐chloroperoxybenzoic acid.
Osmabenzenes can be easily synthesized from two η2‐coordinated olefin osmacycles in the presence of benzonitrile by means of facile hydrogen‐transfer conversions (see graphic). Mechanisms for the formation of osmabenzenes are proposed based on DFT calculations.
Flexible rigidity : Tetralactam macrocycles of the Hunter type bear a rigid scaffold (see space‐filling representation), but can still widely adapt to the properties of a guest molecule inside their cavities. X‐ray crystal structures of a series of differently substituted macrocycles reveal a remarkably broad variety of intermolecular hydrogen‐bonding patterns organizing the macrocycles in the crystals in intriguingly different ways.
The missing link : Ferrocene and porphyrin monolayers are tethered on silicon surfaces with short (see picture, left) or long (right) linkers. Electron transfer to the silicon substrate is faster for monolayers with a short linker.
Positive discrimination : Chemo‐ and regioselective palladium‐catalyzed cycloetherification of allendiols, namely β,γ‐ and γ,δ‐allendiols, may occur by judicious choice of palladium‐catalyzed conditions owing to their potential ability to discriminate between both nucleophilic sites (see scheme).
Don′t tell azole : The first metal‐catalyzed direct coupling of metal sulfides with aryl halides and subsequent intramolecular condensation provided substituted benzothiazoles (see scheme). A wide range of functional groups are tolerated under the reaction conditions.
Caught in the middle : The ionomycin calcium complex (see structure; O red, Ca green) was the target of an approach featuring the efficient asymmetric synthesis of an allene by a copper(I)‐mediated anti‐selective SN2′ reaction, a highly stereoselective gold(III)‐catalyzed cycloisomerization of an α‐hydroxyallene, and a Rh‐catalyzed rearrangement of an α‐diazo‐β‐hydroxyketone.
A real turn‐on : The emission intensity of heterocycle 1 increases upon binding to Pb2+. Thus, 1 acts as a small‐molecule “turn‐on” fluorescent sensor for lead. The sensor is highly selective and is functional over a wide range of pH values.
Dramatic rate enhancement of reductive elimination of [Ar‐Pd‐C] was observed in the presence of a phosphine/electron‐deficient olefin ligand. Through systematic kinetic investigations of the Negishi coupling of ethyl 2‐iodobenzoate with alkylzinc chlorides (see scheme), the rate constants for reductive elimination of [Ar‐Pd‐C] were determined to be greater than 0.3 s?1, which is about four or five orders of magnitude greater than values reported previously.
Finely tuned optical properties : The optical properties of substituted protected catechol derivatives can be fine‐tuned (see scheme; TBDMS=tert‐butyldimethylsilyloxy). The DFT‐calculated polarisabilities are compared with experimental data.
The novel Yb succinate metal–organic framework exhibits a reversible single‐crystal to single‐crystal polymorphic transformation (see figure) when it is heated above 130 °C, returning to its initial form when back at room temperature. This transformation produces a change in the coordination sphere of the Yb atoms, which influences the catalytic activity of the material.
Reacting in the 'Ni'ck of time : The title reaction is realized by using an isolated NiII complex ( 1 ). The catalysis tolerates a wide range of important functional groups that are often incompatible with Grignard reagents in cross‐coupling reactions.
Bringing order : A new class of periodic mesoporous organosilicas (PMOs) with a urea‐bridged organosilica precursor under acid‐catalyzed and inorganic‐salt‐assisted conditions was obtained. The large‐pore hybrid materials have ordered mesostructure with uniform pore size distributions, which can be seen from the TEM images.
Reversible and non‐bonding interaction between SWNTs and ODCB is observed from the analyses of visible near‐infrared absorption data and Raman spectroscopies (see spectra). The solvent effect on SWNTs effectively controls the electronic structure of SWNTs under homogeneous conditions.
