Perfetti Mauro, Cucinotta Giuseppe, Boulon Marie-Emmanuelle, El Hallak Fadi, Gao Song, Sessoli Roberta
Dipartimento di Chimica Ugo Schiff, Università degli Studi di Firenze, Via della Lastruccia 3-13, 50019 Sesto Fiorentino (Italy).
Chemistry. 2014 Oct 20;20(43):14051-6. doi: 10.1002/chem.201404218. Epub 2014 Sep 11.
The experimental investigation of the molecular magnetic anisotropy in crystals in which the magnetic centers are symmetry related, but do not have a parallel orientation has been approached by using torque magnetometry. A single crystal of the orthorhombic organometallic CpErCOT [Cp=pentamethylcyclopentadiene anion (C5Me5(-)); COT=cyclooctatetraenedianion (C8H8(2-))] single-molecule magnet, characterized by the presence of two nonparallel families of molecules in the crystal, has been investigated above its blocking temperature. The results confirm an Ising-type anisotropy with the easy direction pointing along the pseudosymmetry axis of the complex, as previously suggested by out-of-equilibrium angular-resolved magnetometry. The use of torque magnetometry, not requiring the presence of magnetic hysteresis, proves to be even more powerful for these purposes than standard single-crystal magnetometry. Furthermore, exploiting the sensitivity and versatility of this technique, magnetic anisotropy has been investigated up to 150 K, providing additional information on the crystal-field splitting of the ground J multiplet of the Er(III) ion.
对于磁中心具有对称关系但取向不平行的晶体中的分子磁各向异性的实验研究，已经通过使用转矩磁强计得以开展。对正交晶系有机金属化合物CpErCOT [Cp = 五甲基环戊二烯阴离子 (C5Me5(-)); COT = 环辛四烯二价阴离子 (C8H8(2-))] 单分子磁体的单晶进行了研究，该晶体的特征是在晶体中存在两个不平行的分子族，研究温度高于其阻塞温度。结果证实了一种伊辛型各向异性，其易轴沿着配合物的伪对称轴方向，这正如之前非平衡角分辨磁强计所表明的那样。转矩磁强计的使用不需要磁滞现象的存在，事实证明，对于这些目的而言，它比标准的单晶磁强计更为强大。此外，利用该技术的灵敏度和通用性，对高达150 K的磁各向异性进行了研究，提供了关于Er(III)离子基态J多重态的晶体场分裂的更多信息。
