Dynamical effects on the magnetic properties of dithiazolyl bistable materials.
Dynamical effects on the magnetic properties of dithiazolyl bistable materials.
复制标题
DOI：
10.1039/c4sc03930k
复制
发表时间：
2015-04-01
期刊：
影响因子：
8.4
通讯作者：
Ribas-Arino J
中科院分区：
文献类型：
--
作者：
Vela S;Deumal M;Shiga M;Novoa JJ;Ribas-Arino J
使用1,3,5-三硫-2,4,6-三氮杂戊烯基材料作为概念证明，我们证明了自由基的振动可以在定义某些有机磁体的磁性能中发挥主要作用。分子基磁体的磁性通常只考虑所研究系统的单一核构型（通常是x射线晶体结构）。在这里，通过计算研究，我们将使用这种静态方法获得的结果与明确考虑热波动获得的结果进行了比较，并揭示了静态视角在处理自由基经历宽幅度运动的磁性晶体时的严重局限性。作为概念证明，这些限制说明了磁性双稳态1,3,5-三硫-2,4,6-三氮杂戊烯基（TTTA）材料。在300 K的高温阶段，我们发现核动力学诱导自旋之间的磁交换相互作用（J AB）的大波动（高达平均值的1000%）。这些偏差导致通过明确考虑核动力学计算的300 K磁化率与使用x射线结构计算的磁化率之间存在约20%的差异，前者与实验数据更符合。揭示的jab相互作用与分子间振动之间的强耦合表明，将jab视为给定温度下的恒定值（就像分子磁学中经常做的那样）会导致对TTTA磁性的错误描述。相反，在这种情况下，物理上相关的概念是jab值的统计分布。单一x射线结构不足以解释TTTA的磁性，这一发现也有望在其他有机磁体中发挥决定性作用，这些有机磁体的主要交换相互作用通过不稳定的π -π网络传播。
Using 1,3,5-trithia-2,4,6-triazapentalenyl material as a proof of concept, we demonstrate that vibrations of radicals can play a prime role in defining the magnetic properties of certain organic magnets. The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study (usually an X-ray crystal structure). Here, by means of a computational study, we compare the results obtained using such a static approach with those obtained by explicitly accounting for thermal fluctuations, and uncover the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for the magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. For its high-temperature phase at 300 K, we show that nuclear dynamics induce large fluctuations in the magnetic exchange interactions (J AB) between spins (up to 1000% of the average value). These deviations result in a ∼20% difference between the 300 K magnetic susceptibility computed by explicitly considering the nuclear dynamics and that computed using the X-ray structure, the former being in better agreement with the experimental data. The unveiled strong coupling between J AB interactions and intermolecular vibrations reveals that considering J AB as a constant value at a given temperature (as always done in molecular magnetism) leads to a flawed description of the magnetism of TTTA. Instead, the physically relevant concept in this case is the statistical distribution of J AB values. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile π–π networks.
登录
查看更多内容
影响因子：
15
作者：
Fujita, Wataru;Awaga, Kunio;Kagoshima, Seiichi
通讯作者：
Kagoshima, Seiichi
影响因子：
4.4
作者：
BECKE, AD
通讯作者：
BECKE, AD
影响因子：
2.3
作者：
Alberola, Antonio;Burley, Jonathan;Rawson, Jeremy M.
通讯作者：
Rawson, Jeremy M.
影响因子：
4.3
作者：
Deumal, M;Bearpark, MJ;Novoa, JJ
通讯作者：
Novoa, JJ
影响因子：
3.3
作者：
Domingo, Alex;Verot, Martin;Robert, Vincent
通讯作者：
Robert, Vincent