Development of porous molecular lattice materials showing guest-responsibility based on a mechanism of host-guest electron transfer

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18925
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Tohoku University
• Principal Investigator: Miyasaka Hitoshi 東北大学, 金属材料研究所, 教授 (50332937)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: ホスト-ゲスト相互作用 / 電荷移動型錯体格子 / 磁気変換 / 多孔性材料 / ヨウ素 / 酸化還元

Outline of Final Research Achievements

Host-guest electron transfer (HGET) in molecular framework systems, such as metal-organic frameworks (MOFs), is a critical trigger for implementing drastic changes in both the host framework and the guest, and can enable possible modulation of the electronic and magnetic properties of frameworks. Post-synthetic incorporation of redox-active guests into redox-active MOFs is a fascinating strategy for achieving guest-driven reversible HGET. Herein, we demonstrated an HGET-induced magnetic phase switch between an antiferromagnet for guest-free form and a paramagnet for I2-loaded form. Furthermore, the I2-loaded form exhibited a hundred-fold enhancement in electrical conductivity compared to that of guest-free form owing to the electron hopping. The regulation of magnetism and electrical conductivity via HGET, which was demonstrated for the first time in this study, can facilitate the design of new porous magnets.

Free Research Field

錯体化学

Academic Significance and Societal Importance of the Research Achievements

「多孔性磁石」は、従来からよく知られた電場・磁場・光・圧力などの物理的な刺激とは異なり、「分子吸脱着」という化学的な刺激により駆動する材料である。化学物質の性質を磁化という物理量に換える、「化学―物理変換」を可能にする材料と言い換えることもできる。本研究における、吸着分子とホスト骨格の間での直接的な電子授受により駆動する可逆磁気相変換は世界初観測であり、新たな駆動原理により「化学物質による物性制御」を実現したという点で、高機能分子デバイスの実現へ向けて、基礎・応用の両面から大変意義深い結果だと考えられる。