| POLYMERS Vol.63 No.4 |
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COVER STORY
Polymer for and in Confined Space |
| COVER STORY: Highlight Reviews |
| Crystallization-Free Crystallography Utilizing Nano-Space of Porous Complexes | Yasuhide INOKUMA, Makoto FUJITA |
| <Abstract> A new method of X-ray crystallographic analysis that does not require crystallization of target compounds has been developed. A variety of compounds including oily ones and scarce amount of natural products have been successfully analzed with this method. Keywords: X-Ray Crystallography / Porous Coordination Networks |
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| Polymer Chemistry in Coordination Nanospaces | Takashi UEMURA |
| <Abstract> Recently, Metal-Organic Frameworks (MOFs) prepared by self-assembly of metal ions and organic ligands have attracted much attention. The characteristic features of MOFs are high regularity because of the crystalline nature, controllable pore sizes approximating molecular dimensions, and designable pore surface functionality. Thus, use of their regulated and tunable nanochannels for fields of polymerization can allow multi-level controls of the resulting polymer structures, such as molecular weight, stereoregularity, chain alignement, and so on. In addition, polymers confined in the nanochannels show properties different from those of the bulk polymers, providing unprecedented material platforms to accomplish many nanoscale functions. Keywords: Metal-Organic Framework / Nanochannel / Controlled Polymerization / Nanoconfinement / Nanocomposite |
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| COVER STORY: Topics and Products |
| Porous Organic Cages - Soluble Molecular Pores | Andrew I. Cooper and Tom Hasell |
| <Abstract> Most synthetic materials that give rise to molecular scale porosity are extended frameworks or networks. There are relatively few examples of discrete porous molecules. In the last few years, our group has reported a range of such porous “cage” molecules, and a number of these will be highlighted here, within the context of related research. The solubility of the cages allows them to be solution processed in ways that would not be possible for a macromolecular network. They can be blended with other soluble materials, deposited inside porous supports, and cast as films or coatings. The solubility also allows the cages to be directed into different crystal polymorphs, using appropriate directing solvents, or combined as co-crystals in a modular ‘mix-and-match’ strategy. Keywords: Intrinsic Microporosity / Gas Sorption / Gas Separation / Porous Organic Cages / Polymers / Crystal Engineering / Adsorption |
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| Novel Crystalline-State Polymerization of Metal Organic Frameworks (MOF) | Kazuki SADA, Kenta KOKADO |
| <Abstract> Polymerization in confined space has been attracting considerable interest. In this short review, we propose a new kind of crystalline-state polymerization by using metal organic framework (MOF) crystals. MOF is nano-porous crystalline materials constructed by metal ions and rigid organic linkers equipped with two or more ligation sites to form robust 3D host framework with nano-pores. The void space between them is wide and stable, which prompted us to investigate cross-linking of the organic linkers by two chemical reactions; (1) azide-tagged MOF (AzM) cross-linked by multi-alkyne cross-linkers via click reaction and (2) cyclodextrin MOF (CD-MOF) cross-linked by glycidyl ethers. They represent new crystalline-state polymerization techniques, because the cross-linking takes place between the host components fixed at the wall of the host framework and the guest monomers included in the host framework. Moreover, they provide polyhedral gels with well-defined edges and faces. The shape and size of the starting MOF crystals are retained after cross-linking and decomposition of coordination bonds. Keywords: Metal Organic Framework (MOF) / Crystalline-State Polymerization / Inclusion Polymerization / Confined Space / Click Reaction / Cyclodextrins |
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| Functions and Properties of Isolated π-Conjugated Polymers | Kazunori SUGIYASU |
| <Abstract> We have synthesized π-conjugated polymers, in which the conjugated backbones are sheathed within its own cyclic side chains. The structure is reminiscent of electric power cords; as such, π-π stacking between the polymer backbones is prevented, and thus, the materials reflect the electronic properties of the single polymer structure. Herein, we describe our recent studies on such ‘isolated’ conjugated polymers with focusing on their electronic and photophysical functions. Keywords: Conjugated Polymers / Molecular Wires / Conducting Mechanism / Fluorescent Materials |
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| Aromatic Micelles with Anthracene Shells | Kei KONDO, Michito YOSHIZAWA |
| <Abstract> Micelles are spherical assemblies of amphiphilic molecules with hydrophilic heads and hydrophobic tails. Inspired by the micelle structures, we designed new amphiphiles providing two or three anthracene panels connected through meta-phenylene spacers functionalized with hydrophilic groups. A new class of micelle-like molecular capsules was formed by the assembly of the bent amphiphilic molecules in water by π-stacking and hydrophobic interactions. The micellar capsules could accommodate various organic molecules (e.g., fluorescent dyes), and the resultant nano-composites exhibited unique emission properties through efficient host-guest interactions. Keywords: Anthracene / Assembly / Capsule / Fluorescence / Micelle |
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| Metal Array Fabrication Based on the Self-Assembly of Metalated Amino Acids and -Peptides | Hikaru TAKAYA, Masaharu NAKAMURA, Kastuhiro ISOZAKI |
| <Abstract> Various types of metalated amino acids and peptides, in which a variety of functional transition-metal complexes covalently tethered to their α-side chain, were sucssessfully synthesized and their self-assembly properties for the fabrication of well-ordered metal arrays were investigated. Intermolecular hydrogen bonds induced self-assembly of these amino acids and peputide to afford β-sheet type supraolecular aggregation with well aligned metal complexes, resulting in perfect controll of 1D- and 2D-metal sequences as demostrated by using cryo-TEM-based electron diffraction and synchrotron WAX and SAXS analyses. Enhanced Enhanced catalysis were observed catalysis were observed in the Pd- and Pt-binding amino acids/peptide supramolecular aggregates. Keywords: Amino Acid / Peptide / Metal Array / Supramolecuar Gel |
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| Controlled Arrangements of Fullerenes within Nano Space of Self-Assembling Porphyrins | Fumito TANI |
| <Abstract> In order to construct controlled arrangements of fullerenes, we have prepared cyclic porphyrin dimers (M2-CPD, M=Ni, H2), which include fullerenes with high affinities (Kassoc ≈ 105 M-1). These dimers have two self-assembling 4-pyridyl groups at the opposite meso positions. In crystals, inclusion complexes of C60 and PCBM within the nickel dimer (C60⊂Ni2-CPD and PCBM⊂Ni2-CPD) result in a linear array of the fullerene molecules in the self-assembled porphyrin nanotube, which is formed by the stacking of the cyclic dimer through the non-classical hydrogen-bonding interactions between pyridyl nitrogens and pyrrole β C-H groups. In contrast, the inclusion complexes of C60 and C70 within the free-base dimer (C60⊂H4-CPD and C70⊂H4-CPD) afford zigzag arrays of the fullerene molecules without the formation of nanotube structure. Owing to the well-controlled arrangement of C60 above mentioned, C60⊂Ni2-CPD and C60⊂H4-CPD exhibit high electron mobility (Σμ > 0.1 cm2V-1s-1) along the array. Moreover, C60⊂H4-CPD undergoes photoinduced electron transfer from the porphyrin to C60 to produce a charge-separated state. Keywords: Fullerene / Porphyrin / Self-assembly / Nanotube / Supramolecule / Host-Guest Chemistry / Photoinduced Electron Transfer / Charge Mobility |
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| Polymer Science and I: A Personal Account |
| OMOROI (means “Fascinating”) | Shohei IDA |
| <Abstract> In my high school days, the teacher guided me to the world of chemistry. Here, I look back on my career started following the teacher's direction. He might have expect that I make an academic career in polymer science. |
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| Front-Line Polymer Science |
| Self-Assembly of Complex Polymer Systems with Supramolecular Interactions | Yushu MATSUSHITA |
| <Abstract> Recent progress in complex structure formation via self-assembly of block copolymers coupled with supramolecular interaction is reported. The content comprises of three parts, (I) Morphology control of complex systems having hydrogen bonding interaction, (II) Formation of periodic structures from block coplymer/metal compounds, or block copolymer/metal nanoparticle hybrids with supramolecular interactions, and (III) Creation of nonoporous materials by way of hybrids based on self-assmbly of block copolymers. Furthermore, category (I) includes three sub-themes that all deal with hydrogen bonding interactions, i.e., 1) block copolymer/homopolymer or low molecular weight organic compound blends, 2) block copolymer/block copolymer blends, and 3) block copolymer type supramacromolecules, while category (II) is composed of 1) block copolymer/metal salt hybrids, and 2) block copolymer/matal nanoparticles or semiconductor nanoparticle hybrids. Keywords: Self-Assembly / Block Copolymer / Microphase Separation / Supramolecular Interaction / Hydrogen Bonding / Hierarchical Structure / Hybrids / Metal Nanoparticles |
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