Light-induced excited spin state trapping effect on [Fe(mepy)3tren](PF6)2 solvated crystals.
Light-induced excited spin state trapping effect on [Fe(mepy)3tren](PF6)2 solvated crystals.
复制标题
光诱导激发自旋态对 [Fe(mepy)3tren](PF6)2 溶剂化晶体的捕获效应。
作者：
A. Tissot;E. Rivière;R. Guillot;L. Toupet;E. Collet;M. Boillot
合成了一种自旋交叉的溶剂化化合物[Fe（mepy）3 tren]（PF_6）_2·C_7H_8·C_2H_3 N，并与文献报道的非溶剂化固体的开关性质进行了比较.的热自旋转变发生在88 K与开放的3.5 K宽的磁滞回线，而一个相当陡峭的过渡在215 K没有滞后先前已报道的非溶剂化类似物。这一特点已被合理化的高自旋（HS）和低自旋（LS）结构的分析，证明了相对稳定的高自旋状态，以及强分子间相互作用的溶剂化化合物。溶剂化固体的光开关，基于光诱导激发自旋态俘获效应，导致在10 K下从低自旋到高自旋态的定量转变。在10 K的亚稳态HS状态的长寿命允许测量的光致HS结构，其中的合作相互作用增强，相比于那些的热填充HS结构。然后，在45 - 60 K之间研究了HS-to-LS弛豫。它们是S形的，可以很好地拟合在平均场近似的框架。光诱导的HS状态在这个家庭的自旋交叉化合物的相对稳定性是没有直接关系到他们的热自旋转变温度。这种意想不到的观察是合理的，仔细分析其结构特征。
A spin-crossover solvated compound [Fe(mepy)3tren](PF6)2·C7H8·C2H3N has been prepared and its switching properties have been compared to those reported for the non-solvated solid. The thermal spin transition occurs at 88 K with the opening of a 3.5 K wide hysteresis loop, while a fairly steep transition at 215 K without hysteresis has been previously reported for the non-solvated analogue. This feature has been rationalized by the analysis of the high-spin (HS) and low-spin (LS) structures, evidencing a relative stabilization of the high-spin state, as well as strong intermolecular interactions in the solvated compound. The photoswitching of the solvated solid, based on the light-induced excited spin state trapping effect, leads to a quantitative transformation from the low-spin to the high-spin state at 10 K. The long lifetime of the metastable HS state at 10 K allows the measurement of the photo-induced HS structure, where the cooperative interactions are enhanced, compared to those of the thermally populated HS structure. Then,the HS-to-LS relaxations have been studied between 45 and 60 K. They are sigmoidal in shape and can be well fitted in the frame of the mean-field approximation. The relative stability of the photo-induced HS state in this family of spin crossover compounds is not directly related to their thermal spin transition temperature. This unexpected observation is rationalized by a careful analysis of their structural characteristics.