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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11603-11607
Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] ( 1Dy Cpttt=1,2,4‐tri(tert ‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ ( 2Dy ) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [ 2Dy ][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doublets correspond to a well‐defined MJ value, with no significant mixing even in the higher doublets. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(32):9504-9508
Mechanical anisotropy is ubiquitous in biological tissues but is hard to reproduce in synthetic biomaterials. Developing molecular building blocks with anisotropic mechanical response is the key towards engineering anisotropic biomaterials. The three‐way‐junction (3WJ) pRNA, derived from ϕ 29 DNA packaging motor, shows strong mechanical anisotropy upon Mg2+ binding. In the absence of Mg2+, 3WJ‐pRNA is mechanically weak without noticeable mechanical anisotropy. In the presence of Mg2+, the unfolding forces can differ by more than 4‐fold along different pulling directions, ranging from about 47 pN to about 219 pN. Mechanical anisotropy of 3WJ‐pRNA stems from pulling direction dependent cooperativity for the rupture of two Mg2+ binding sites, which is a novel mechanism for the mechanical anisotropy of biomacromolecules. It is anticipated that 3WJ‐pRNA can be used as a key element for the construction of biomaterials with controllable mechanical anisotropy. 相似文献