| POLYMERS Vol.64 No.11 |
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COVER STORY
Discerning (or Discernible) Molecular and Macromolecular Function Deduced from Twisting Structure |
| COVER STORY: Highlight Reviews |
| Helical Conjugated Polymers with Super-Hierarchically Controlled Structures | Kazuo AKAGI |
| <Abstract> The π-conjugated polymers bearing π-electrons delocalized over the main chains are extensively investigated from viewpoints of fundamental and applied sciences because of their unique optoelectronic properties and functions. Nowadays it is further required for the conjugated polymers, as next-generation plastic electronics materials, to have newly designed polymer structures, novel functions and high performance in optoelectronic functions. Herein, we discuss helical π-conjugated polymers with super-hierarchically controlled structures, by focusing on (i) optically active polymers with white colored circularly polarized luminescence (CPL) and intensity amplification of CPL via liquid crystalinity, (ii) external stimulus-responsive π-conjugated polymers and reversible switching in CPL, and (iii) interchain helically stacked assemblies consisting of cationic achiral π-conjugated polymers and anionic chiral molecules and the formation of spherulites based on the polymer assemblies. Keywords: Conjugated Polymers / Helical Structures / Hierarchical Control / Circular Polarization / Dissymmetry Factor in Luminescence |
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| Synthesis and Helical Function of Polysaccharide Supramolecules by Vine-Twining Polymerization | Jun-ichi KADOKAWA |
| <Abstract> Polysaccharides with helical conformation, such as amylose, are known to form supramolecules by complexation with appropriate compounds. Recently, investigations concerning the formation of supramolecules, i.e., inclusion complexes, formed by amylose and polymeric guests, have been extensively conducted. This review deals with the dynamic preparation of amylose-polymer inclusion complexes in amylose-forming polymerization field. Helical functions by amylose in the process are also disclosed. Keywords: Polysaccharide / Amylose / Enzymatic Polymerization / Inclusion Complex / Supramolecule |
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| Helicity in Tubular Carbonaceous Molecules (or Finite Carbon Nanotube Molecules) | Taisuke MATSUNO, Hiroyuki ISOBE |
| <Abstract> Structural chemistry of carbon nanotubes started flourishing by the advent of finite molecular versions. The discrete molecular structures of finite carbon nanotube molecules deepen the chemical understanding of these intriguing molecular entities. Keywords: Carbon Nanotube / Chirality / Helicity / Moleculr Entity / Finite Carbon Nanotube Molecules |
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| COVER STORY: Topics and Products |
| Twisting of π-Conjugated Plane to One Rotation | Satoru HIROTO, Hiroshi SHINOKUBO |
| <Abstract> We have established the facile and efficient protocol to synthesize distorted π-conjugated molecules. Oxidation of amino-substituted porphyrins proceeded with high regioselectivity to produce pyrazine fused dimers. X-ray diffraction analysis revealed its highly twisted structure. Electrochemical and optical measurements indicated the twisting mostly influences on HOMO. The sequential use of our protocol has achieved the synthesis of unidirectionally twisted porphyrin tetramers efficiently. NMR analysis suggested that the racemization barrier of twisting increases on oligomerization. To the best of our knowledge, this is the first observation of a similar phenomenon observed in polymer science for twisted π-conjugated molecules. The present findings represent an important advance towards the long-term goal of preparing π-conjugated molecular wires, whose properties can be fine-tuned through molecular twisting. Keywords: Distorion / π-Conjugated Molecule / Twist / Oxidation / Porphyrin / Anthracene / Oligomer |
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| Optically Active π-Electron Systems Based on Planar Chiral Compounds | Yasuhiro MORISAKI |
| <Abstract> Planar chirality is one of the unique properties of [2.2]paracyclophane compounds derived from suppression of the rotation of stacked phenylenes. Recently, we have developed the optical resolutions of rac-disubstituted [2.2]paracyclophane and rac-tetrasubstituted [2.2]paracyclophane. In addition, we have synthesized various optically active conjugated polymers, oligomers, and cyclic compounds based on the planar chiral [2.2]paracyclophane skeleton. The obtained optically active compounds exhibited good optical profiles, with a large molar extinction coefficient and photoluminescence quantum efficiency. The optically active higher-ordered structure provided chiroptical properties of high performance, such as a large specific rotation and molar ellipticity in the ground state and intense circularly polarized luminescence (CPL) with large dissymmetry factors in the exited state. The results suggest that planar chiral [2.2]paracyclophane-based optically active higher-ordered structures, such as the one-handed helix and propeller-shaped cyclic structure, are promising scaffolds for obtaining CPL and that appropriate modifications can enhance the CPL characteristics. Keywords: Cyclophane / Circularly Polarilzed Luminescence / Conjugated Polymer / Higher Ordered Structure / Optical Resolution / Photoluminescence / Planar Chirality |
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| Supramolecular Allosteric Signal-amplification Sensing Based on the Structural Changes of Flexible Polymer Backbones | Gaku FUKUHARA |
| <Abstract> Supramolecular sensing with polymers has attracted much attention not only in fundamental science but also in a number of practical applications, since polymers can amplify binding events to greatly enhance signal gains upon interactions with analytes. We have recently developed a novel polymer-based sensing strategy, “supramolecular allosteric signal-amplification sensing”. In this Topics, the novel sensing systems with recent our examples are highlighted. Keywords: Allosterism / Polythiophene / Curdlan / Chirality / Amino Acids / Peptides / Oligosaccharides |
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| Polymer Science and I: A Personal Account |
| Interdisciplinary Research Fields | Atsuomi SHUNDO |
| <Abstract> I have traveled around several research fields. New findings and insights may exist in between the interdisciplinary research fields. |
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| Front-Line Polymer Science |
| Interaction between Topological Defects of Liquid Crystals and Polymers | Hirotsugu KIKUCHI, Hiroki HIGUCHI, Yasushi OKUMURA, Kenji HIGASHIGUCHI |
| <Abstract> Around the topological defects of a liquid crystal, there are gradients of the director distortions and the orientational order, where a long range elastic force field is created. When polymers are placed in the field, an attractive force along the gradient, toward the defect core, is imposed to the particles. By this long-range force, the particles are migrated and finally trapped by the defect. The polymer-stabilized liquid crystal blue phases, which show fast electro-optic effect, are stabilized by this kind of effect. Recent research progresses on the related phenomena are briefly reviewed in this paper. Keywords: Liquid Crystal / Topological Defect / Particles / Blue Phase |
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