配位高分子および金属－有機構造体ガラスにおける電荷移動に関する研究

京都大学新制・課程博士博士(工学)甲第24587号工博第5093号新制||工||1975(附属図書館)京都大学大学院工学研究科合成・生物化学専攻(主査)教授 古川 修平, 教授 生越 友樹, 准教授 堀毛 悟史, 教授 松田 建児学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA

Metal-Organic Network-Forming Glasses

The crystal–liquid–glass phase transition of coordination polymers (CPs) and metal–organic frameworks (MOFs) offers attractive opportunities as a new class of amorphous materials. Unlike conventional glasses, coordination chemistry allows the utilization of rational design concepts to fine-tune the desired properties. Although the glassy state has been rare in CPs/MOFs, it exhibits diverse advantages complementary to their crystalline counterparts, including improved mass transport, optical properties, mechanical properties, and the ability to form grain-boundary-free monoliths. This Review discusses the current achievements in improving the understanding of anomalous phase transitions in CPs/MOFs. We elaborate on the criteria for classifying CP/MOF glasses and comprehensively discuss the three common strategies employed to obtain a glassy state. We include all CP/MOF glass research progress since its inception, discuss the current challenges, and express our perspective on future research directions

Proton-conductive coordination polymer glass for solid-state anhydrous proton batteries

Designing solid-state electrolytes for proton batteries at moderate temperatures is challenging as most solid-state proton conductors suffer from poor moldability and thermal stability. Crystal–glass transformation of coordination polymers (CPs) and metal–organic frameworks (MOFs) via melt-quenching offers diverse accessibility to unique properties as well as processing abilities. Here, we synthesized a glassy-state CP, [Zn₃(H₂PO₄)₆(H₂O)₃](1, 2, 3-benzotriazole), that exhibited a low melting temperature (114 °C) and a high anhydrous single-ion proton conductivity (8.0 × 10⁻³ S cm⁻¹ at 120 °C). Converting crystalline CPs to their glassy-state counterparts via melt-quenching not only initiated an isotropic disordered domain that enhanced H⁺ dynamics, but also generated an immersive interface that was beneficial for solid electrolyte applications. Finally, we demonstrated the first example of a rechargeable all-solid-state H+ battery utilizing the new glassy-state CP, which exhibited a wide operating-temperature range of 25 to 110 °C

Exploration of glassy state in Prussian blue analogues

Prussian blue analogues (PBAs) are archetypes of microporous coordination polymers/metal–organic frameworks whose versatile composition allows for diverse functionalities. However, developments in PBAs have centred solely on their crystalline state, and the glassy state of PBAs has not been explored. Here we describe the preparation of the glassy state of PBAs via a mechanically induced crystal-to-glass transformation and explore their properties. The preservation of short-range metal–ligand–metal connectivity is confirmed, enabling the framework-based functionality and semiconductivity in the glass. The transformation also generates unconventional CN(−) vacancies, followed by the reduction of metal sites. This leads to significant porosity enhancement in recrystallised PBA, enabled by further accessibility of isolated micropores. Finally, mechanical stability under stress for successful vitrification is correlated to defect contents and interstitial water. Our results demonstrate how mechanochemistry provides opportunities to explore glassy states of molecular framework materials in which the stable liquid state is absent

Exploration of glassy state in Prussian blue analogues

Prussian blue analogues (PBAs), a class of microporous crystalline coordination frameworks, are long known for their diverse properties in porosity, magnetic, charge transport, catalysis, optics, and more. Versatile structural composition and the ability to control defect ordering through synthetic conditions offer opportunities to manipulate the functionality in the crystalline state. However, developments in Prussian blue analogues (PBAs) have primarily revolved around the ordered crystalline state, and the glassy state of PBAs has not yet been explored. Here we report the discovery of a disordered glassy state of the PBA via mechanically induced crystal–glass transformation. We found the preservation of metal–ligand–metal connectivity, confirming the short-range order and semiconductor behaviour, exhibiting an electronic conductivity value of 0.31 mS cm−1 at 50 ˚C. Mechanical-induced glass transformation also triggers changes in electronic states, where electroneutrality is compensated by introducing unconventional CN− vacancies. Partial disorders and ligand vacancies in recrystallized PBA give rise to an enhanced porosity, inaccessible in the crystalline parent. The present work also established a correlation between the mechanical stress required to initiate crystal–glass transformation and intrinsic mechanical properties, which are controlled by the vacancy/defect content, the presence of interstitial water, and the overall composition of PBAs