| 研究実績の概要 |
This year, following the research objective of searching for novel functional luminescent single-molecule magnets (SMMs) based on lanthanide complexes, I have focused on the magnetic and luminescent studies on a cyanido-bridged d-f bimetallic coordination framework built of Tb(III) and hexacyanocobaltate(III). Single crystal structure study unveiled that this framework can bear a topotactic transformation between an as-synthesized hydrated phase, {[Tb(H2O)2][Co(CN)6] 2H2O}0.7H2O, and its dehydrated phase, Tb[Co(CN)6], reversibly induced by room temperature hydration and thermal dehydration. As a consequence, the functional center, Tb(III) ion, exhibits a switchable characteristics on both magnetic and luminescent properties. Upon dehydration, the Tb complex converts into a highly symmetric trigonal prism geometry, which leads to a very large magnetic anisotropy with Orbach energy barrier over ca. 450 cm^(-1). Such high value is comparable to the very historical yet best Tb(III)- phthalocyaninato SMM system, and we proudly introduce a totally new class of high-performance Tb(III)-SMM in this work. In addition, the Tb-centered luminescence intensity and spectral pattern change due to the variation of ligand field, resulting in a modified optical thermometric characteristic. Notably, the working temperature ranges of SMM behavior and the optical thermometry for the dehydrated phase overlap largely between 6 K to 45 K. Such temperature overlap is to-date the widest, and it opened great possibility of real-time temperature monitoring for the functioning center of a SMM.
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