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

研究了一系列双核铁配合物[{Fe（NCS）（py-X）}_2（bpypz）_2]的光磁性质，其中bpypz = 3，5-双（2-吡啶基）吡唑，X = 4-甲基吡咯（1），吡啶（3），3-甲基吡咯（4），3-环丙基吡啶（5）和3-溴吡啶（6）.反射率T（LIESST）温度以及动力学衰减。所有这些配合物显示出中心在100-150 K之间的完整的热自旋转变，并在低温下经历光诱导激发自旋态捕获（LIESST）效应。的T（LIESST）的光致高自旋态的弛豫温度为每个化合物已被确定。它们的低温T（LIESST）曲线都接近于[{Fe（NCS）（3，5-Me_2py）}_2（bpypz）_2]（7）配合物的反铁磁响应，为LS-LS → HS-HS光转换过程提供了定量证据。根据协同效应的性质，动力学已被处理与拉伸指数，简单指数或S形模型。有趣的是，这一系列双核配合物的T（LIESST）与它们的热自旋转变温度T_（1）之间存在一个线性关系<v2>：T（LIESST）= T_0- 0.3T_1_（<v2>0）= 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，认为配合物7的HS-HS性质反映了T（LIESST）高于T_（1/2）的物理不可能性<v2>。通过施加流体静压，连续地检查了7号上热自旋交叉现象的邻近区域。

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.