TY - JOUR
T1 - Opening Magnetic Hysteresis by Axial Ferromagnetic Coupling: From Mono‐Decker to Double‐Decker Metallacrown
AU - Wang, Jin
AU - Li, Quan‐Wen
AU - Wu, Si‐Guo
AU - Chen, Yan‐Cong
AU - Wan, Rui‐Chen
AU - Huang, Guo‐Zhang
AU - Liu, Yang
AU - Liu, Jun‐Liang
AU - Reta, Daniel
AU - Giansiracusa, Marcus J.
AU - Wang, Zhen‐Xing
AU - Chilton, Nicholas F.
AU - Tong, Ming‐Liang
PY - 2021/3/1
Y1 - 2021/3/1
N2 - 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-MCCu-5] (1-Dy) SMM, where a DyIII ion is held in a central pseudo-D5h pocket of a rigid and planar Cu5 metallacrown (MC). Linking two Dy[15-MCCu-5] units with a single hydroxide bridge yields the double-decker {Dy[15-MCCu-5]}2 (2-Dy) SMM where the anisotropy axes of the two DyIII 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 YIII-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.
AB - 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-MCCu-5] (1-Dy) SMM, where a DyIII ion is held in a central pseudo-D5h pocket of a rigid and planar Cu5 metallacrown (MC). Linking two Dy[15-MCCu-5] units with a single hydroxide bridge yields the double-decker {Dy[15-MCCu-5]}2 (2-Dy) SMM where the anisotropy axes of the two DyIII 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 YIII-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.
U2 - 10.1002/anie.202014993
DO - 10.1002/anie.202014993
M3 - Article
SN - 1433-7851
VL - 60
SP - 5299
EP - 5306
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 10
ER -