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Opening Magnetic Hysteresis by Axial Ferromagnetic Coupling: From Mono‐Decker to Double‐Decker Metallacrown
Author(s) -
Wang Jin,
Li QuanWen,
Wu SiGuo,
Chen YanCong,
Wan RuiChen,
Huang GuoZhang,
Liu Yang,
Liu JunLiang,
Reta Daniel,
Giansiracusa Marcus J.,
Wang ZhenXing,
Chilton Nicholas F.,
Tong MingLiang
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202014993
Subject(s) - remanence , ferromagnetism , magnetic anisotropy , magnetization , hysteresis , relaxation (psychology) , ion , condensed matter physics , chemistry , magnetic hysteresis , single molecule magnet , anisotropy , dysprosium , crystallography , magnetic field , physics , inorganic chemistry , organic chemistry , quantum mechanics , psychology , social psychology
Combining Ising‐type magnetic anisotropy with collinear magnetic interactions in single‐molecule magnets (SMMs) is a significant synthetic challenge. Herein we report a Dy[15‐MC Cu ‐5] ( 1‐Dy ) SMM, where a Dy III ion is held in a central pseudo‐ D 5 h pocket of a rigid and planar Cu 5 metallacrown (MC). Linking two Dy[15‐MC Cu ‐5] units with a single hydroxide bridge yields the double‐decker {Dy[15‐MC Cu ‐5]} 2 ( 2‐Dy ) SMM where the anisotropy axes of the two Dy III ions are nearly collinear, resulting in magnetic relaxation times for 2‐Dy that are approximately 200 000 times slower at 2 K than for 1‐Dy in zero external field. Whereas 1‐Dy and the Y III ‐diluted Dy@ 2‐Y analogue do not show remanence in magnetic hysteresis experiments, the hysteresis data for 2‐Dy remain open up to 6 K without a sudden drop at zero field. In conjunction with theoretical calculations, these results demonstrate that the axial ferromagnetic Dy–Dy coupling suppresses fast quantum tunneling of magnetization (QTM). The relaxation profiles of both complexes curiously exhibit three distinct exponential regimes, and hold the largest effective energy barriers for any reported d–f SMMs up to 625 cm −1 .