| POLYMERS Vol.71 No.9 |
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COVER STORY
Aggregation-Induced Functions: A Gift from Gathering |
| COVER STORY: Highlight Reviews |
| Principles of Aggregation - Induced Emission | Gen-ichi KONISHI |
| <Abstract> Aggregation-induced emission luminogens (AIEgens) exhibit non-luminescence in solution and strong luminescence in solid state. Twenty years ago, the concept of AIE was proposed, and this unique luminescent property has attracted scientific interest. This review provides principles of AIE and the characteristics and future applications of AIEgens. Keywords: Aggregation-Induced Emission / Fluorescence Dye / Photochemistry / Organic Light-Emitting Materials / Bio-Imaging / Analytical Chemistry / Stimuli-Responsive Materials |
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| Control of Assembly-Induced Luminescence for Platinum(II) Complexes | Masako KATO |
| <Abstract> Square-planar platinum(II) complexes with the d8 configuration often exhibit distinct color and luminescence when the complex units are stacked with short Pt…Pt contacts. Since such assembly-induced coloration and luminescence can change sensitively reflecting the assembled structure, they are applicable for tracking the dynamics of supramolecular formation and monitoring the environment. Moreover, by the precise control of the assembled structures, it is possible to realize a variety of luminescent colors and to construct chromic complexes that are responsive to external stimuli. Keywords: Lumienscence / Platinum(II) Complex / Soft Crystal / Assembly / Vapochromism / Chromic Complex / Phase Transition |
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| Aggregation-Induced Delayed Fluorescence | Takuma YASUDA |
| <Abstract> Organic luminescent materials that can emit delayed fluorescence involve unique photophysical behavior different from conventional fluorescent materials. How can we induce novel unique photofunctions in the molecular aggregation systems against the concentration quenching? In this report, the author introduces recent examples of organic delayed fluorescence materials that demonstrate unique luminescent characteristics in their aggregation states. Keywords: Aggregation / Concentration Quenching / Delayed Fluorescence / Exciton / Mechanochromic Luminescence / Organic Light-Emitting Diodes / Triplet |
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| COVER STORY: Topics and Products |
| Photocatalytic Activity Induced by Self-Assembly of Organic Dyes | Hajime SHIGEMITSU, Toshiyuki KIDA |
| <Abstract> Photocatalysts are essential materials for artificial photosynthesis. Herein, we introduce supramolecular photocatalysts consisting of hydrophilic organic dyes. The organic dyes without photocatalytic properties in the monomer state acquired this property by self-assembly owing to the formation of the charge separated state. The supramolecular photocatalysts are applied to hydrogen evolution and photooxidation reactions in water, and photodynamic therapy. Keywords: Supramolecular Assembly / Photocatalyst / Hydrogen Evolution / Photooxidation / Photodynamic Therapy / Water |
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| Mechanism and Potential Applications of Aggregation-Induced Emission at Liquid-Liquid Interfaces | Hirohisa NAGATANI |
| <Abstract> An interface between two immiscible electrolyte solutions (ITIES) has been utilized as a simple model of biomembrane surface to evaluate mass transport process and pharmacokinetics. Various species indicate self-aggregation features at ITIES, where the extent of aggregation of ionic species can reversibly be controlled by applying external potential. The potential-driven aggregation accompanied by a colorimetric response is favorable for bioimaging applications since the membrane potential of the living cell plays a crucial role in physiological processes. Most of the fluorescent dyes used in biochemical applications, however, exhibit emission properties in the aggregation-caused quenching (ACQ) mechanism, and this restricts their usefulness. In this article, the fundamental mechanism of transfer and adsorption of ionic dyes at ITIES under electrochemical control are described briefly. The recent findings on aggregation induced emission (AIE) of water-soluble tetraphenylethene derivatives at ITIES and at a phospholipid-adsorbed biomimetic interface will also be discussed in terms of its potential applications in spectrophotometric characterization of bio-tissues. Keywords: Liquid-Liquid Interface / Ion Transfer / Adsorption / Aggregation Induced Emission |
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| Boronate Supramolecules with Aggregation-Induced Emission Properties | Yuji KUBO |
| <Abstract> Molecular self-organization is one of the most promising methods to create nano- or microscopic structures in supramolecular chemistry. Current interest for preparation of functional solids hierarchically built up by using organic molecules have motivated chemists to use aggregation-induced emission (AIE) molecules that serve as efficient building blocks for endowing self-organized molecular systems with luminescent properties. Here, our successful examples such as AIE-active boronate nanoparticles and chemometrics-coupled chiral sensing using AIE boronate ensembles are presented. In the former, making use of facile dye-grafting at the surface of boronate particles, multi-color emission, involving white-light, was attained through Fröster resonance energy transfer process. In the latter case, two types of boronic acid-appended D-π-A cyanostilbenes were synthesized and produce chiral ensembles by dehydration with tartaric acid. Fingerprint-like emission response to chiral analytes is suitable for chiral sensing with linear discriminant analysis and artificial neural network. Well-tailored combination of boronate supramolecules and AIE function is discussed from standpoint of developing emissive nanomaterials. Keywords: Aggregation-Induced Emission / Supramolecules / Dynamic Covalent Bond / Boronic Acid / Tetraphenylethylene / Cyanostilbene / Chiral Sensing / Chemometrics |
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| AIE Characteristics of Distorted Triskelion-Shaped Coumarin Dyes | Masafumi UEDA |
| <Abstract> This study reports the synthesis and properties of twisted triskelion-shaped AIE-gen bearing three coumarin units (1). X-ray crystallography revealed that 1 adopts a distorted and propeller-shaped geometry. Furthermore, compound 1 has two molecular π-surfaces with differing electrostatic potentials as with Janus-type molecules. Two enantiomers consisting of right-handed PPP-1 and left-handed MMM-1 existed as racemic mixture in the crystal structure. Theoretical calculation suggests that the ΔG‡ in this molecular inversion between PPP-1 and MMM-1 was 9.0 kcal/mol. Therefore, compound 1 undergoes its helical inversion with ease. Interestingly, this twisted framework bearing coumarin dye formed nanoaggregates in THF/H2O. The particle size was ca. 190～295 nm. Compound 1 exhibits favorable aggregation-induced emission enhancement based on the distorted geometry. This supports that helical inversion of 1 is inhibited in the nanoaggregates, as the result, non-radiation deactivation process due to molecular vibration is restricted by fixed molecular conformation. Keywords: Aggregation-Induced Emission Enhancement / Coumarin / Distorted Triskelion / Janus-Type Structure / Molecular Helical Inversion |
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| Polymer Science and I: A Personal Account |
| Let’s Keep Trying! | Mari MIYATA |
| <Abstract> Research that pursues unknown things and truths is fascinating, and I want to be a person who can convey the joy of research to students and those around them. I would like to continue to take on challenges without forgetting to thank the many people involved in my research activities. |
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| Front-Line Polymer Science |
| Enzymatic Biofuel Cells Using Redox Polymers | Takanori TAMAKI |
| <Abstract> Enzymatic biofuel cells utilize the ability of enzymes to oxidize or reduce various substances to convert the chemical energy of fuels into electricity. One important topic in enzymatic biofuel cells has been the electron transfer between enzymes and electrodes. Except for enzymes that undergo direct electron transfer, redox mediators shuttle electrons between enzymes and electrodes. When mediators are immobilized to polymers, creating so-called redox polymers, the apparent diffusion coefficient of mediators decreases. Thus, the apparent diffusion of mediators becomes the rate-limiting step in the electrodes with thick redox polymer films. The rational design of electrodes by combining high-surface-area electrodes and thin redox polymer films is required to fully utilize the high intrinsic activity of enzymes. Recent advances in the design methodology for electrodes of enzymatic biofuel cells using redox polymers and the application as implantable and wearable devices are introduced in this article. Keywords: Biofuel Cell / Redox Polymer / Mediator / Enzyme / Graft Polymerization / Carbon / Surface Modification |
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