Construction of novel spin-crossover systems by nano space control of assemblies

研究了bpypz = 3,5-双（吡啶-2-酰基）吡唑酸酯和X = 4- mepy(1)、py(3)、3- mepy(4)、3- cipy(5)和3- brpy(6)的一系列[{Fe(NCS)(py-X)}_2(bpypz)_2]族双核二铁（II）配合物的光磁性能。反射率T（LIESST）温度以及动力学衰减。所有这些配合物在100- 150k之间表现出完整的热自旋跃迁，并在低温下发生光诱导激发自旋态捕获（LIESST）效应。测定了每种化合物光致高自旋态的T（LIESST）弛豫温度。它们在低温下的T（LIESST）曲线都接近于以HS电子构型为特征的两个铁（II）金属离子[{Fe (NCS)(3,5- me_2py)}_2(bpypz)_2](7)配合物的反铁磁响应，为定量的LS-LS→HS-HS光转换过程提供了一些证据。根据协同性的性质，动力学可以用拉伸指数模型、简单指数模型或s型模型来处理。有趣的是，这一系列双核配合物遵循先前提出的T（LIESST）与其热自旋转变温度之间的线性关系：T(LIESST) = T_0-0.3 T1_<v2>这些化合物的To等于100 K。在此基础上，利用热自旋跃迁与Hammett常数之间的经验线性关系，将配合物7的HS-HS性质理解为T（LIESST）高于T_<v2>的物理不可能性的反映。通过施加静水压力，连续检查了7上热自旋交叉现象的近距离。

Photomagnetic properties of a series of binuclear diiron(II) complexes belonging to the [{Fe(NCS)(py-X)}_2(bpypz)_2] family with bpypz = 3,5-bis (pyridine-2-yl)pyazolate and X = 4-Mepy (1), py (3), 3-Mepy (4), 3-Cipy (5) and 3-Brpy (6) have been investigated. The reflectivity T(LIESST) temperatures as well as the kinetic decays. All these complexes display a complete thermal spin transition centred between 100-150 K, and undergo the light-induced excited spin state trapping (LIESST) effect at low temperatures. The T(LIESST) relaxation temperature of the photoinduced high-spin state for each compound has been determined. For all of them the T(LIESST) curves at low temperature have been found close to antiferromagnetic response of the [{Fe (NCS)(3,5-Me_2py)}_2(bpypz)_2] (7) complex characterized by two iron(II) metal ions in HS electronic configuration, giving some evidences of a quantitative LS-LS → HS-HS photoconversion process. Depending on the nature of the cooperativity, kinetics have been treated with stretched exponential, simply exponential or sigmoidal model. Interestingly this series of dinuclear complexes follow a previously proposed linear relation between T(LIESST) and their thermal spin-transition temperatures T_<v2>: T(LIESST) = T_0-0.3 T1_<v2> To for these compounds is equal to 100 K. Based on that and by using the empirical linear relation found between the thermal spin transition and the Hammett constant, the HS-HS properties of complex 7 have been understood as a reflect of the physical impossibility that the T(LIESST) was higher than T_<v2>. The close vicinity of the thermal spin crossover phenomenon on 7 has been successively checked by applying hydrostatic pressure.