Influence of Guest Exchange on the Magnetization Dynamics of Dilanthanide Single-Molecule-Magnet Nodes within a Metal-Organic Framework

• Published in: Angewandte Chemie (International ed.) Vol. 54; no. 34; pp. 9861 - 9865
• Main Authors: Zhang, Xuejing, Vieru, Veacheslav, Feng, Xiaowen, Liu, Jun-Liang, Zhang, Zhenjie, Na, Bo, Shi, Wei, Wang, Bing-Wu, Powell, Annie K., Chibotaru, Liviu F., Gao, Song, Cheng, Peng, Long, Jeffrey R.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 17-08-2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc; Wiley Blackwell (John Wiley & Sons)
• Edition: International ed. in English
• Subjects: ab initio calculations; Arrays; Barriers; Dynamics; Exchange; host-guest systems; lanthanides; Magnetic induction; Magnetic permeability; Magnetic relaxation; Magnetic susceptibility; Magnetization; Magnets; Metal clusters; Metal-organic frameworks; Nodes; Quantum tunnelling; Single crystals; single-molecule magnets; Solvents; Three dimensional; ab initio calculations; host-guest systems; single-molecule magnets; lanthanides; metal-organic frameworks
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201503636

Multitopic organic linkers can provide a means to organize metal cluster nodes in a regular three‐dimensional array. Herein, we show that isonicotinic acid N‐oxide (HINO) serves as the linker in the formation of a metal–organic framework featuring Dy2 single‐molecule magnets as nodes. Importantly, guest solvent exchange induces a reversible single‐crystal to single‐crystal transformation between the phases Dy2(INO)4(NO3)2⋅2 solvent (solvent=DMF (Dy2‐DMF), CH3CN (Dy2‐CH3CN)), thereby switching the effective magnetic relaxation barrier (determined by ac magnetic susceptibility measurements) between a negligible value for Dy2‐DMF and 76 cm−1 for Dy2‐CH3CN. Ab initio calculations indicate that this difference arises not from a significant change in the intrinsic relaxation barrier of the Dy2 nodes, but rather from a slowing of the relaxation rate of incoherent quantum tunneling of the magnetization by two orders of magnitude.
Guest swap: Exchange of the guest molecules within the pores of a metal–organic framework (MOF) featuring Dy2 single‐molecule magnets as nodes imparts major changes in the magnetization relaxation dynamics (see picture; spectra recorded from 2 K (blue plots) to 9 K (red)). As a result of guest exchange, significantly different effective relaxation barriers (Ueff) for the compound are measured. Atom colors: Dy=green, O=red, N=blue, C=gray.