Volume 79, Issue 9

The 12th International Conference on Polymers and Organic Chemistry (POC'06) was held in Okazaki, Japan, from 2-7 July 2006 and was attended by nearly 200 participants from 20 different countries. This was the second time that POC was held in Japan, the first time was in 1990 (1982, Lyon, France; 1984, Lancaster, UK; 1986, Jerusalem, Israel; 1988, Barcelona, Spain; 1990, Kyoto, Japan; 1994, Venice, Italy; 1996, Wroclaw, Poland; 1998, Maa'ale Hachamisha, Israel; 2000, Tianjin, China; 2002, San Diego, USA; 2004, Prague, Czech Republic). The aim of this series of symposia is to bring together chemists from different chemical fields to define and discuss the most recent developments in the areas of polymer-supported reagents, polymeric catalysts, polymers in medicine and biochemistry, polymers for separations, electro- and light-sensitive functional polymers, polymers for environmental protection, processes within functional polymers, and so on. Plenary lectures were provided by Profs. Yoshio Okamoto (Nagoya University, Japan) and Jean M. J. Fréchet (University of California, Berkeley, USA). Along with the plenary lectures, nine invited lectures featured recent advances in the field of polymer-based chemistry in organic synthesis by David E. Bergbreiter, Kuiling Ding, Shu Kobayashi, Yoon-Sik Lee, Helma Wennemers, Pradeep K. Dhal, Toshihide Inoue, Eiji Yashima, and Peter A. G. Cormack. These lectures, as well as 27 oral presentations of the selected papers, exhibited the strength, diversity, and novelty with which this scientific field is being practiced. In addition, there were 55 poster presentations. Ten articles contributed by the lecturers and the conference chairs of POC'06 appear in this issue of Pure and Applied Chemistry in order to provide a summary of last summer's conference. Shinichi Itsuno POC'06 Co-chair Yasuhiro Uozumi POC'06 Co-chair and Conference Editor

Polymer-supported chiral 1,2-diamine derivatives have been prepared. The polymers containing free 1,2-diamine moiety were applied to enantioselective hydrogenation catalyst by combination with RuCl 2 -BINAP complex. Asymmetric hydrogenation of aromatic ketones was performed by means of the polymeric catalyst derived from these polymers to give the chiral secondary alcohols with high ee in quantitative conversion. The polymers containing 1,2-diamine monosulfonamide were applied to enantioselective transfer hydrogenation catalyst by combination with RuCl 2 - p -cymene complex. Asymmetric transfer hydrogenation of aromatic ketones was performed by means of the polymeric catalyst to afford the chiral secondary alcohols. A high level of enantioselectivities up to 99 % ee was attained in neat water by using the polymeric catalyst prepared from quaternary ammonium salt-type polymer support.

A novel homochiral phosphine ligand, (3 R ,9a S )[2-aryl-3-(2-diphenylphosphino)phenyl]tetrahydro-1 H -imidazo[1,5- a ]indole-1-one, was designed, prepared, and anchored onto an amphiphilic polystyrene-poly(ethylene glycol) copolymer (PS-PEG) resin. Catalytic asymmetric substitution of a racemic mixture of cycloalkenyl esters with carbon, nitrogen, and oxygen nucleophiles was achieved in water as the single reaction medium under heterogeneous conditions by using the PS-PEG resin-supported palladium-imidazoindole phosphine complex to give optically active substituted cycloalkenes with up to 99 % ee.

The de-ironing of water is a basic stage in water-treating technology. Consequently, the oxidation of easily soluble Fe(II) to poorly soluble Fe(III) compounds is indispensible. In order to oxidize Fe(II) ions to Fe(III), a macromolecular and macroporous product in bead form was used: polystyrene cross-linked by divinylbenzene, which contains pendant N -chlorosulfonamide groups in both the sodium and hydrogen forms. To assist the process of removing residual iron from water, this polymer - a macromolecular analog of Chloramine T, containing more than 4.0 mequiv of active chlorine/g - was prepared, starting from the sulfonate cation exchanger Amberlyst 15 by a three-step transformation of its functional groups. The investigations were carried out using both the batchwise and column methods, and 0.0025 M as well as 0.02 M FeSO 4 solutions with different acidity were used. We found that the oxidation of ferrous ions to ferric by N -chlorosulfonamide copolymer was effective and was favored by a low pH. The oxidative ability of the copolymer was 225 mg Fe(II)/g. We established that the oxidation reaction could be operated in two directions. In acidic media (pH < 2.5), Fe(III) ions remained in the solution as products of the reaction. The higher the pH, the more the poorly soluble ferric compounds sedimented in the inner structure of the copolymer beads. In this way, new hybrid materials were obtained, i.e., by ferrous/ferric oxides and hydroxides, by nanoparticles, modified materials which can serve as specific reacting sorbents and catalysts.

In this paper, the synthesis and characterization of molecularly imprinted spherical polymer particulates prepared via precipitation polymerization is described. The effects of the monomer and initiator concentrations and the solvent on the polymerizations were investigated systematically. Polymer microspheres with narrow size distributions and average diameters up to ca. 10 μm were prepared under optimized polymerization conditions. The morphologies of the microspheres were characterized by nitrogen sorption porosimetry and the molecular recognition properties of representative products evaluated in high-performance liquid chromatography (HPLC) mode. Imprinting effects were confirmed by analyzing the relative retentions of the analytes on imprinted and non-imprinted packed HPLC columns. Finally, two different agitation/mixing methods for precipitation polymerizations were compared. It was found that the use of a low-profile roller housed inside a temperature-controlled incubator had advantages over a rotavapor-based system. Overall, this study has served to highlight the attractiveness of precipitation polymerization for the routine production of molecularly imprinted polymers in a well-defined spherical particulate form via an efficient one-step synthetic process.

In recent years, functional polymers exhibiting inherently biological activities have been receiving increasing attention as polymer-based human therapeutic agents. These polymeric drugs exhibit unique pharmaceutical properties that are fundamentally different from their traditional small-molecule counterparts. However, unlike polymeric drug delivery systems, examples of polymers possessing intrinsically therapeutic properties are relatively scarce. By virtue of their high-molecular-weight characteristics, these polymeric drugs can be confined to the gastrointestinal (GI) tract, where they can selectively recognize, bind, and remove target disease-causing substances from the body. Being confined to the GI tract and non-biodegradable, these polymeric drugs are free from toxic effects that are associated with traditional systemic drugs. This report highlights recent developments in the rational design and synthesis of appropriate functional polymers that have resulted in a number of promising polymer-based therapeutic agents, including some marketed products.

The development of a new strategy to immobilize the homogeneous chiral catalysts for enantioselective reactions is highly desirable in order to overcome some drawbacks of conventional approaches. In this lecture, a conceptually new strategy for heterogenization of homogeneous chiral catalysts (i.e., "self-supporting" approach) is presented. The concept focuses on the use of homochiral metal-organic coordination polymers generated by self-assembly of chiral multitopic ligands with metal ions as the heterogeneous catalysts, and thus obviating the need of any exogenous support. The application of this "self-supporting" strategy has been exemplified in heterogeneous catalysis of asymmetric carbonyl-ene, sulfoxidation, and epoxidation, as well as asymmetric hydrogenation reactions.

We discuss the future directions for the research and development of polyester-based materials. In the discussion of polyesters as industrial materials, one direction is the development of high-performance materials. Poly(ethylene terephthalate) (PET), known as one of the most important polyesters, was developed early in the 1940s. We discuss two approaches to the development of high-performance materials suitable for injection-molding applications using PET units. The first approach is development of high-performance materials by copolymerization with bibenzoic acid (BB), which has a rigid structure, and the second approach is development of liquid-crystal polyesters (LCPs) with superior thermal resistance and excellent flowability using PET units. The other future direction for research and development is the targeting of environmentally friendly materials. Poly(lactic acid) (PLA), derived from bio-based materials, is a very important material because it can realize the carbon neutral cycles. Nevertheless, the practical properties of PLA itself are unsatisfactory compared to other plastics derived from fossil resources. We have developed PLA-based polymer alloys with various practical properties by utilizing a newly developed nanoalloy technology.

1-Methyl-3-(3-trimethoxysilylpropyl)imidazolium chloride, [TMSPIM][Cl - ], was synthesized as a precursor of N -heterocyclic carbene (NHC), which can be coordinated with palladium to give an organosilane-based bidentic NHC-Pd complex. The organosilane-based NHC-Pd complex was immobilized covalently on silica particles (NHC-Pd/silica) and then characterized by field emission/scanning electron microscopy (FE/SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIRS), and inductively coupled plasma/atomic emission spectroscopy (ICP/AES). The Suzuki reaction was performed as a model reaction to examine the catalytic activity of NHC-Pd/silica. NHC-Pd/silica exhibited excellent performance in the Suzuki reaction of various aryl halide derivatives (except for aryl chloride derivatives) with phenylboronic acid under mild conditions (room temperature and short reaction time). Moreover, the catalyst was recycled several times without any significant loss of catalytic activity in the Suzuki reaction.

The chromatographic separation of enantiomers using chiral stationary phases (CSPs) has significantly advanced. The esters and carbamates of polysaccharides coated on silica gel have been extensively studied and widely used as CSPs for high-performance liquid chromatography (HPLC). In order to overcome the strict solvent limitation on these coated CSPs, the preparation of a new generation of CSPs consisting of immobilized polysaccharide derivatives has become increasingly important. The universal solvent compatibility of the new CSPs provides flexibility in both analytical and preparative chromatographies.

Monodisperse biotinylated poly(styrene- co - N -acryloxysuccinimide) microspheres were synthesized in aqueous solutions with a two-step method. Upon the addition of avidin solutions of different concentrations in phosphate buffer into the dispersed biotinylated microspheres, the microspheres aggregated rapidly due to the high binding affinity between biotin and avidin. The hydrodynamic diameter of the aggregates and the aggregation rate observed at given time intervals increased with increasing concentration of avidin. The composition of the microspheres and the incorporation of biotin were evidenced by Fourier transform infrared spectroscopy. The morphology, size distribution, and aggregation of the microspheres were studied by techniques such as scanning electron microscopy and dynamic light scattering.

The objective of the "Explanatory Dictionary of Key Terms in Toxicology" is to give full explanations of the meaning of toxicological terms chosen for their importance and complexity from the point of merging chemistry and toxicology. This requires a full description of the underlying concepts, going beyond a normal dictionary definition. Often linguistic barriers lead to problems in obtaining a common understanding of terminology at the international level and between disciplines. The explanatory comments should help to break down such barriers. The dictionary consists of about 68 terms chosen from the IUPAC "Glossary of Terms Used in Toxicokinetics" organized under 22 main headings. The authors hope that among the groups which will find this explanatory dictionary helpful are chemists, pharmacologists, toxicologists, risk assessors, regulators, medical practitioners, regulatory authorities, and everyone with an interest in the relationship of chemistry to toxicology. It should also facilitate the use of chemistry in relation to risk assessment.