| POLYMERS Vol.69 No.8 |
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COVER STORY
Constructing Spaces from Polymers |
| COVER STORY: Highlight Reviews |
| Creation of Superspace that Recognizes, Arranges, and Activates Molecules | Mitsuhiko SHIONOYA |
| <Abstract> This paper introduces examples of porous crystals with molecular recognition sites and a new type of porous crystal, Metal-Macrocycle Framework, with multiple different molecular recognition sites that we have developed, and describes a future prospect. Keywords: Superspace / Porous Crystal / Molecular Recognision / Molecular Arrangement / Molecular Activation |
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| Applications of Periodic Mesoporous Organosilicas | Shinji INAGAKI |
| <Abstract> Periodic mesoporous organosilicas (PMOs) have mainly two characteristic features, first that an organic group having various functions can be introduced within the framework and second that they have relatively large pores (2 － 30 nm in diameter) formed using surfactant micelles as a template. This article describes unique applications of PMOs based on their characteristic features. A light-harvesting photocatalysis system for CO2 reduction was constructed by using acridone-PMO and a ruthenium-rhenium dinuclear complex immobilized in the mesopores. A PMO containing 2,2’-bipyridine ligands within in the framerwork showed excellent ligand properties for heterogeneous Ir-catalyzed direct C-H borylation of arenes. A PMO film containing laser light-absorptive organic groups could be used as a substrate for matrix-free laser desorption/ionization mass spectrometry. A breakable PMO with organic groups containing disulfide bonds could be applied to a stimuli-responsible drug delivery system. Keywords: Mesoporous Organosilica / Light Harvesting / Metal Complex / Solid Support / Laser Desorption / Ionization / Mass Spectrometry / Drug Delivery System |
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| COVER STORY: Topics and Products |
| Nanospace in Liquid Crystals | Shin-ichiro KAWANO, Kentaro TANAKA |
| <Abstract> Shape-persistent macrocyclic mesogens in thermotropic liquid crystals have potential uses in highly customizable nanochannels through stacking, which could lead to novel porous soft materials for use as molecular recognition sites, organizers of entrapped molecules, and nanoreactors in flowable media. We have synthesized thermotropic liquid-crystalline (LC) macrocycles composed of carbazole and salphen with 1.4 nm sized inner cavity which can accommodate guest molecules. The LC behavior is also drastically affected by the metal coordination in the salphen ligand. Furthermore, we have an extended discrete inner cavity of a columnar LC macrocycle with a larger pi-conjugated building block. The inner cavity was as large as 2.5 nm in diagonal. The giant macrocycle with branched alkyl chains showed the thermotropic LC properties below 213℃. To best of our knowledge, the giant macrocycle contained the largest discrete inner space among the thermotropic columnar liquid crystals composed of the macrocyclic mesogens. Keywords: Nanospace / Liquid Crystals / Macrocycles / Supramolecular Chemistry / Host-Guest Complex |
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| Porous Soft Materials Comprised of Self-Organized Metal-Organic Cages | Nobuhiko HOSONO |
| <Abstract> There is a common perception that porous materials are solid and crystalline. Is this really true? Recently, porous soft materials that possess both permanent porosity and fluidity have emerged as a new class of porous materials. We have developed porous soft materials using metal-organic cages (MOCs) as a “modular pore” to be organzed into porous soft materials. To give fluidity and malleability to the MOCs, polymers are attached directly on the MOCs, which results in polymer-grafted MOCs. The polymer-grafted MOCs allow formation of viscous fluids that have a nanoporous cavity in their molecular structure. Furthermore, the MOCs form into a lyotropic liquid crystalline phase that has regular ordering in the cavity structure. This bottom-up synthetic approach for the porous soft materials using MOC enables us to synthesize new porous soft materials that satisfy both processability and ordered pore structures, which have been considered difficult properties to be achieved simultaneously in the conventional porous solids. Keywords: Porous Material / Metal-Organic Cage / Polymer Hybrid / Graft Polymerization / Liquid Crystal / Self-Organization |
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| Development of Metal-Doped Conjugated Microporous Polymers for Electrocatalytic Applications | Kazuhide KAMIYA |
| <Abstract> Conjugated microporous polymers (CMPs) have attracted increasing attention as novel polymeric materials due to their unique physicochemical properties, such as their nano-porous structure, mechanical robustness and high design flexibility. Recently, we have demonstrated that triazine-linked CMPs can support a wide variety of metals in their pores via coordination bonds. Interestingly, the metal-doped CMPs (M-CMPs) exhibited unique electrocatalytic functions depending on the metal species: for example, single Pt-doped CMP and Ni-doped CMP could serve as an electrocatalyst for oxygen-tolerant hydrogen oxidation and carbon dioxide reduction, respectively. Considering the abundance in choice of monomers, M-CMPs are becoming the promising platform of heterogeneous electron-transfer catalysts. Keywords: Conjugated Microporous Polymer / Covalent Organic Frameworks / Electrocatalysts / Hydrogen Oxidation Reactions / CO2 Electrolysis |
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| Porous Molecular Crystals Constructed Through Well-Organized Hydrogen Bonding | Ichiro HISAKI |
| <Abstract> Porous molecular crystals constructed through hydrogen bonding, which are often called hydrogen-bonded organic frameworks (HOFs), have recently attracted much attention. HOFs with permanent porosity were thought for long time to be difficult to construct due to the weakness of reversible hydrogen bonds. However, well-designed hydrogen bonds, combined with the use of rigid, shape-persistent π-conjugated moieties, enables us to construct exotic HOFs with permanent porosity. This article describe the author’s approach to construct such HOFs based on C3-symmetric π-conjugated molecules possessing o-bis(4-carboxyphenyl)aryl moieties in their periphery. Structures and properties of HOFs with a 2D hexagonal network, interpenetrated 3D pcu-network, and more complicated networks are presented. Keywords: Porous Framework / Permanent Porosity / Hydrogen Bond / Topology / Molecular Crystal / Gas Sorption / Acid Responsiveness |
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| Biomolecular Recognition by Aromatic Nanospaces | Ryuki SUMIDA, Michito YOSHIZAWA |
| <Abstract> Here we report the resent progress in the research of our molecular capsules with well-defined, aromatic nanospaces. The capsules are quantitatively formed by the self-assembly of two metal ions and four bent bispyridine ligands with two polyaromatic panels. In water, the aromatic nanospace displays unusual high affinity toward androgens (i.e., male hormones). For example, androgenic testosterone is quantitatively and exclusively encapsulated by the capsule even from a complex mixture with progesterone and β-estradiol, known as representative female hormones. In addition, long, linear, and flexible fatty acids with oligo- and polyunsaturated carbon-carbon double bonds (e.g., α-linolenic acid and EPA) are selectively bound by the capsule cavity in water, through effective hydrophobic effects and CH-π/π-π interactions. Notably, otherwise labile polyunsaturated fatty acids (e.g., DHA) are significantly stabilized against light, heat, and oxygen upon encapsulation by the capsule. Keywords: Capsule / Nanospace / Polyaromatic / Recognization / Biomolecule / Water |
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| Polymer Science and I: A Personal Account |
| Driving Force for Research Work | Hitomi HAYASHIBARA |
| <Abstract> This column is about my research experience and where my motivation comes from. While doing Ph.D., rarely appearing and unexpected phenomena were very interesting to me so that I decided to continue my study till successfully obtaining my Ph.D. After entering a company, I have the dream that one day the product I develop will be manifactured and goes on sale. |
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| Front-Line Polymer Science |
| Functional Surface Acheicved by Polymer Brushes | Motoyasu KOBAYASHI |
| <Abstract> Two decades have already passed since the well-defined polymer brushes had been prepared by surface-initiated controlled polymerization. Surface-tethered polymers with high graft density called as polymer brushes have been attracted much attention due to its specific chain structures in a good solvent and wide application of surface modification with various functionality, such as wettability control, antifouling, adhesion, lubrication, and biomaterial. This article reviews recent development of the science and applications of polymer brushes, and also current issues and future challenges. Keywords: Polymer Brushes / Surface Modification / Antifouling / Polyelectrolyte Brushes / Hydrophilic Surface / Nanoparticles |
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