Chemistry – An Asian Journal

Biomimetic fabrication is promising for functionalizing artificial materials with special properties learned from nature; superhydrophobicity is a typical example. However, a superhydrophibic graphene surface created by micro/nanostructuring has not been reported yet. As described in their Communication on page 301 ff., Y. L. Zhang, H. B. Sun et al. present biomimetic graphene surfaces with both superhydrophobicity and bright structural color. The method is so simple that hierarchical micro/nanostructures and the modulation of surface chemical composition were realized synchronously by using two-beam laser interference. The results obtained in this study demonstrate a facile approach to wettability control of graphene.

Fluorogenic protein labeling helps to localize a protein within the cell in the presence of an excess amount of quenched probes. In their Communication on page 272 ff., K. Kikuchi et al. propose an alternative fast approach for fluorogenic protein labeling. The fluorogenicity can be introduced by the removal of a photoinduced electron transfer-based dynamic quencher. This strategy is more effective compared to the removal of a static aggregated quencher. The cover picture illustrates the better visibility of fireworks at the dynamic state (photo taken at the Hanabi festival in Japan; Sujata Kar Saha helped with cover design).

In the spray: Electrospray ionization mass spectrometry has the potential of providing otherwise inaccessible information about the chemistry of polyoxometalates. This Focus Review introduces the concept of electrospray ionization mass spectrometry, gives an overview of examples in the literature of its application to the study of polyoxometalates, and discusses the strengths and limitations of the method in the investigation of reaction dynamics and speciation.

Keeping quenchers on a short leash: Shortening of the linker chain length combined with modification of the quencher moiety was found to improve fluorogenic probes useful for protein labeling by the mutant β-lactamase-tag (BL-tag) technology. The most effective probe, CC3 DNB, displays fluorescence quenching by photoinduced electron transfer (PET) and results in fluorescent protein labeling with fast kinetics.

Stuck on you: Amine-, oxyamine-, and isocyanate-terminated self-assembled monolayers were deposited on silicon wafers for reaction with cobaltabisdicarbollide derivatives. The reaction of the isocyanate group with [NMe₄][8-NH₂-C₄H₈O₂-3,3-Co(1,2-C₂B₉H₁₀)(1,2-C₂B₉H₁₁)] gave homogeneous monolayers of cobaltabisdicarbollide moieties covalently linked to the surface (see picture).

Do the coupling: A palladium-catalyzed oxidative carbonylative coupling process of arylboronic acid with styrenes to chalcone has been developed. The reactions proceed under mild conditions using air as the terminal oxidant reagent.

Nanoparticles meet nanotubes! Direct synthesis of TiN nanoparticles in a three-dimensional network of few-walled carbon nanotubes (FWCNTs) was achieved by using mesoporous graphitic carbon nitride (C₃N₄) as both a hard template and a nitrogen source. The TiN/FWCNT composite showed high performance for the oxygen reduction reaction in acidic media.

The most stable IPR isomer of C₈₈ fullerene, C₈₈ (17), has been captured by chlorination as C₈₈(17)Cl₁₆ and C₈₈(17)Cl₂₂. X-ray crystallography revealed C_s-symmetrical molecular structures of both compounds, with the former being a substructure of the latter (see picture; C grey, Cl green). The chlorination patterns are characterized by the formation of isolated double CC bonds, benzenoid rings, and, in C₈₈(17)Cl₂₂, a long chain of Cl additions in adjacent positions on the C₈₈ fullerene cage.

One thing leads to another: A novel palladium(II)-catalyzed three-component domino reaction of diyne-enones with nucleophiles and vinyl ketones or acrolein under mild conditions provides efficient, general, and atom-economical access to multifunctionalized 2,3-cyclo[b]furan with a stereodefined tri- or tetrasubstituted olefin.

Instant silylene! LiBr assists the dissociation of 1,2-diaryl-1,2-dibromodisilenes. Reactions with various trapping agents gave products identical to those from corresponding reactions with aryl bromosilylenes. The reaction provides a method for the in situ generation of silylenes under mild conditions, and the reaction rate is increased by the addition of LiBr.

The wonderful world of graphene! A simple one-step fabrication of biomimetic graphene surfaces that possess both superhydrophobicity and bright structural color is presented. By using two-beam laser interference, construction of periodic grating microstructures and removal of hydrophilic oxygen groups were realized at the same time.

In the nickel of time: ortho-Haloketoximes and -ketimines undergo [4+2] cyclization reactions with alkynes, catalyzed by nickel complexes to give highly substituted isoquinolines and isoquinolinium salts, respectively, in good to excellent yields (see scheme).

Zincing outside of the pybox: A ZnEt₂/pybox catalyst promotes the hydrosilylation of carbonyl compounds under mild conditions to afford high yields and good ee values for a broad range of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones.

Solubilizing insoluble dyes! A new series of cholic acid-derived dendritic structures were synthesized and their aggregation in chloroform was studied. These aggregates were used as nanocarriers for hydrophilic dye molecules in chloroform. The influence of chiral aggregates on the chiroptical properties of the dye was studied by induced circular dichroism. Finally, these molecules were investigated for selective extraction of one dye from a blended food color.

The crystal structures of polymorphs, co-crystals, and salts of the anthelmintic drug triclabendazole are discussed in the context of an uncommon variety of polymorphism, namely, tautomeric polymorphism.

Metal-free sensitizer: Four organic dyes based on a 3,6-disubstituted carbazole donor have been synthesized for their potential use as sensitizers in dye-sensitized solar cells. These dyes have high molar extinction coefficients and energy levels suitable for electron transfer from an electrolyte to nanocrystalline TiO₂ particles. Under standard global AM 1.5 solar irradiation, a device using one of the prepared dyes (see graphic) exhibited a calculated efficiency of 6.52 %.

All in one pot! A recyclable, second-generation heterogeneous bifunctional polymer bearing phosphine and amine groups has been synthesized and showed enhanced utility in one-pot Wittig reactions compared to a previously reported related material. This polymer was also used in Wittig reaction cascade processes in which the oxidized polymer formed in the one-pot Wittig reaction served as the catalyst in a subsequent conjugate reduction or reductive aldol reaction (see scheme).

Predisposed to glow: The solid-state circular dichroism and circularly polarized luminescence of a 2-naphthalenecarboxylic acid/amine supramolecular organic fluorophore can be controlled by changing the aryl unit of the chiral 1-arylethylamine component rather than changing the chirality of the 1-arylethylamine itself (see picture).

Salty but sweet: Pyridinium-type salts generated from acetals are effective electrophiles for various carbon nucleophiles. The reactions proceed under very mild (non-acidic) reaction conditions and can tolerate acid-sensitive functional groups (see scheme).

Fluorescence chameleon: The title compound HPQ (see picture) displays fluorescence in the solid state and in solution. Recrystallization from THF yields polymorphs that show differently colored fluorescence (right). In DMF solution, the strong fluorescence of HPQ is selectively blue-shifted upon addition of Zn²⁺ and Cd²⁺ ions (left).

When temperature does matter: The mismatch between the crystal structure of a thioverdazyl adduct and the apparent S=1/2 one-dimensional antiferromagnetic behavior of the magnetic susceptibility is analyzed with ab initio methods. In such organic-radical-based materials, the underlying magnetic behavior is shown to be much more subtle.

Anchor it and speed it up! An enhancement in catalytic alcohol oxidation activity (see figure) is attributed to the presence of nitrogen heteroatoms on the external surface of a support material, which direct adsorption of Pd nanoparticles.

Following orders: The self-assembled structure of alkoxy- and N-alkylcarbamoyl-substituted zinc–tetraphenylporphyrin at the liquid–highly oriented pyrolytic graphite (HOPG) interface was observed using scanning tunneling microscopy. The alkoxy porphyrin showed phase transition from face-on to edge-on ordering, whereas the N-alkylcarbamoyl porphyrin showed persistent edge-on ordering (see figure).

Mix and match: A dynamic combinatorial library of lanthanide complexes was prepared to develop induced-circular-dichroism (CD) chirality probes. It totaled 168 combinations of coordinative N-aromatic chromophores, trivalent lanthanide centers, and guest amino acids. Combinatorial screening led to a new series of induced-CD chirality probes for specific amino acids (see graphic).

Down to the wire: Ferromagnetic single-crystalline Fe_1−xCo_xSi nanowires (NWs) were synthesized by means of a vapor transport method with no catalyst. The magnetotransport properties of the Fe_1−xCo_xSi NW reveal negative anisotropic magnetoresistance owing to dominant spin-down electrons. The various results (see figure) are of interest for spintronic devices.

A great sense of achievement! The performance of nanoporous carbon as an electrode material was investigated and compared with that of bare glassy carbon, graphite microparticles, and carbon nanotubes. Nanoporous carbon was found to exhibit the highest heterogeneous electron transfer (HET) rate among these materials, thus sensing analytes such as NADH, DNA bases, and 2,4,6-trinitrotoluene (TNT) with an improved electrochemical response.

Drug sniffer: A highly sensitive nanoarchitectured platform based on a functionalized Au nanoparticle scaffold for the sensing of biomedically important polyionic drugs has been developed (see scheme).

Bridging inhibition: A series of 12- to 22-membered bicyclic bridged β-lactams were synthesized with the aim of developing new inhibitors of penicillin-binding proteins and feature a planar amide function and no carboxy group (see picture; Boc=tert-butyloxycarbonyl).