Cover Picture: From Singapore to the World: The 15th Asian Chemical Congress (Chem. Asian J. 8/2013)

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Abstract

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The 15th Asian Chemical Congress will take place in Singapore this year, the place of its inception. This issue of Chemistry-An Asian Journal is a special issue dedicated to the occasion. It features top contributions from a selection of invited conference speakers from around the world, and includes Focus Reviews on fullerene nanoarchitectonics and cucurbit[8]uril-based polymers, as well as 23 original research papers. The cover picture shows the merlion, a popular icon of Singapore, roaring to the world about the great chemistry in this issue.

Layered Compounds

Interaction of electron donor and acceptor molecules with graphene and carbon nanotubes brings about major changes in the electronic structure and properties of these nanocarbons. In their Communication on page 1780 ff. (highlighted on the Inside Cover), C. N. R. Rao et al. report that an electron donor such as tetrathiafulvalene (TTF) transfers an electron to graphene-like few-layer MoS2, thus resulting in the formation of the TTF radical cation (TTF+.). This interaction with TTF significantly changes the band gap of MoS2. By contrast, the electron acceptor tetracyanoethylene does not interact with MoS2 as it is a p-type material.

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Asymmetric Synthesis

A highly enantioselective and widely applicable method for the synthesis of various chiral 2-alkyl-1-alkanols, especially those of feeble chirality, has been developed by Ei-ichi Negishi et al. In their Full Paper on page 1829 ff., featured on the Back Cover, the authors report that the (S)- or (R)-enantiomer of 3-iodo-2-alkyl-1-alkanols (1), prepared by the zirconium-catalyzed asymmetric carboalumination of alkenes (ZACA) reaction of allyl alcohol, can be readily purified to the ≥99% ee level by lipase-catalyzed acetylation. Thus, a variety of chiral 2-alkyl-1-alkanols can now be synthesized in high enantiomeric purity (≥99% ee) by Pd- or Cu-catalyzed cross-coupling of (S)-1 or (R)-2 for introduction of various primary, secondary, and tertiary carbon groups with essentially no enantiomeric isomerization.

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Supramolecular Chemistry

Cucurbit[8]uril-based host–guest interactions, which possess high binding constants and good selectivity, have been widely used in the construction of supramolecular architectures. In their Focus Review on page 1626 ff., Xi Zhang et al. specifically summarize the use of cucurbit[8]uril-based host–guest interactions in fabricating water-soluble supramolecular polymers. The high binding constants of cucurbit[8]uril-based host–guest interactions enable supramolecular polymerization under low monomer concentrations. Supramolecular polymers that were constructed through different building blocks, including small molecules, polymers, dendrimers, and proteins, are described.

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Polymerization

Reversible addition–fragmentation chain transfer (RAFT) polymerization is conducted by the addition of a thiocarbonylthio compound (RAFT agent) to an otherwise conventional radical polymerization. The process allows the synthesis of well-defined homo-, gradient, block, and star polymers, and more complex architectures such as microgels and polymer brushes. In their Focus Review on page 1634 ff., Graeme Moad et al. show how the development of RAFT and RAFT application is being facilitated by the adoption of continuous flow techniques using tubular reactors and through the use of high-throughput methodology. Applications described include the preparation of block copolymer semiconductors for optoelectronics, block copolymer therapeutics, and star polymer rheology control agents.

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Metalloenzymes

The design of artificial metalloenzymes has become an important topic in biological chemistry and inorganic chemistry due to their potential applications in nanoscience and biotechnology. Although such systems employ protein assemblies as molecular scaffolds, the important roles of protein assemblies have not yet been systematically investigated. In their Focus Review on page 1646 ff., Takafumi Ueno et al. discuss this "next-generation" field of bioinorganic chemistry, as recently a number of reports on the rational design of protein assemblies for the construction of artificial metalloenzymes in the integration of catalytic reactions with metal complexes, the preparation of biominerals, and mechanistic investigations of biomineralization processes with protein assemblies have been published.

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OLEDs

Two pincer-type cyclometalated Pt(II) arylacetylide complexes that display different kinds of intermolecular interactions were used as emitters in solution-processed organic light-emitting devices, as reported by Chi-Ming Che et al. in their Communication on page 1754 ff. It was found that the Pt(II) complex without intermolecular PtII⋅⋅⋅PtII interaction in the solid state can be used as an emitter for high-efficiency monochromatic OLEDs due to its higher concentration threshold for aggregation formation. By using a bipolar material as a host, a maximum current efficiency of 26.57 cdA−1, with low efficiency roll-off of 16.7% at 1000 cdm−2, has been achieved.

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Sigmatropic Rearrangement

In their Full Paper on page 1786 ff., A. Stephen K. Hashmi et al. show that the activation by a gold catalyst leads to the formation of vinylgold-intermediates bearing an allyloxonium group. The activated allyl fragment then serves as an intramolecular electrophile and substitutes the gold(I) fragment by a [-sigmatropic rearrangement, thereby delivering allylated isochromenes. This goes along with a clean allylic inversion, resembling an acrobat doing a back handspring (see figure; design by Dorothee D. S. Oehler). It was found that the SPhos-gold(I) complex is the best catalyst for this reaction.

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Ancillary