New pH‐sensitive probe design : A peek into the structure of fluorescent proteins led to the synthesis of fluorescent imidazoles. The prepared compounds demonstrated an array of remarkable pH‐dependent optical properties including at least two types of excited‐state charge transfers (see picture).
Codeposition of NO and O 2 diluted in Ne at 6 K yield a ON???OO complex that exhibit strong UV absorption. This complex is converted into NO3 radicals by UV irradiation, and is regenerated by radiation of visible light (see spectra).
Back from obscurity : The practical synthesis of the first six members of the fundamental class of acyclic branched oligoalkenes has been achieved. The syntheses allow access to the target compounds on multigram scales in good yields. Members of the family with even numbers of double bonds are significantly more stable than those with odd numbers (see picture), and exhibit different chemical reactivities in Diels–Alder reactions.
Highly active, selective, and stable : Highly ordered mesoporous carbon without deposition of metal particles catalyzes the oxidative dehydrogenation of ethyl benzene to styrene. A high activity and selectivity as well as long catalytic stability when compared with activated carbon, is observed from this catalyst.
Particle vs tube : The present paper systematically investigates a range of fundamental geometrical and structural features of TiO2 nanotube layers and their effect on the dye‐sensitized solar cell conversion efficiency, to deduce the most promising strategies for improvement. It is found that the performance of the cells strongly depends on the morphology and crystalline structure of the nanotubes.
Borenes and boranes : Silylaminoiminoborenes, such as depicted, were isolated after treatment of halogen triels with silylaminofluoroboranes. In addition, novel aryl‐ and silyl‐substituted diaminofluoroboranes were also prepared in order to substantiate this reaction route.
Modeling magnetism: The antiferromagnetic ground state of the C60/Si(001)‐c(4×4) surface is predicted by means of density functional theory calculations. Two adjacent dangling bonds (DBs) generated by the adsorption of C60 are antiferromagnetically coupled with each other. This study demonstrates that magnetic Si surfaces can be prepared by engineering single Si DBs with unpaired electrons.
Polymer conformations: The picture shows instantaneous conformations of product molecules produced in a catalytic reaction at the head of a polymer chain. The extended (left) and collapsed (right) polymers correspond to chains in good and poor solvent conditions, respectively. The product molecule concentration gradient leads to a directed force on the polymer, so that it functions as a self‐propelled nanomotor.
Weak and robust ? Tetraalkylammonium salts of weakly coordinating fluorinated alkoxyaluminates are easily accessible, chemically robust materials that show interesting physico‐chemical properties like low melting points, high electrochemical stability and electric conductivity in weakly polar solvents such as CH2Cl2, Ph‐F and toluene.
Structural colors: Poly(N‐isopropyl acrylamide) based microgel photonic crystals are fabricated by using a new method called “high‐temperature‐induced hydrophobic assembly”. The assembling conditions affect the water content of the crystals, thus determining their structural color (see image). The obtained photonic crystals are sensitive to solvents, and the reversible changes in their color can be observed with the naked eye.
Asymmetric catalysis : A facile enantioselective Strecker reaction of ketimines with trimethylsilyl cyanide (TMSCN) was realized by employing chiral (S)‐BNPNa 3 e and PBAP as an additive (see image). A wide substrate scope and good‐to‐excellent enantioselectivities were achieved.
Radically different : Contrary to previous proposals, the main reaction of the HO. radical with guanosine or 2′‐deoxyguanosine is the hydrogen abstraction from the NH2 moiety to give a guanyl radical. This radical, characterized by a broad band in the visible region (around 610 nm), undergoes tautomerization to the most stable isomer.
The quaternary king : Azithromycin ( 1 ), which has improved pharmacological profiles compared with erythromycins, was the target of an enantioselective synthesis. All the stereogenic quaternary carbon centers were elaborated by a desymmetrization of 2‐substituted glycerols using a chiral imine/CuCl2 catalyst.
Buckle up! The dimerization of small fluorescent guests is strongly enhanced in presence of a cyclodextrin host. The host cavity acts like a belt to assist the self‐assembly of guests (see picture). Small variations in the guest structure have significant influence on the stability and geometry of the aggregates.
Simple, versatile and green : Diels–Alder “click” chemistry is a simple, versatile and “greener” approach in the design of a diverse range of dendritic macromolecules (see scheme).
Pinches like a crab : The utilization of guanidines as catalysts has been growing at a steady pace. They possess high pKa values and activate through dual hydrogen‐bonding modes of activation. This Focus Review highlights the development of chiral guanidine catalysts in asymmetric organic transformations.
