Dynamical Spin Crossover Phenomenon in Organic-Inorganic Composite Complex and Its Development to Molecular System

有机-无机复合物中的动态自旋交叉现象及其向分子体系的发展

基本信息

批准号：
18350069
负责人：
KOJIMA Norimichi
金额：
$ 9.99万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

In the case of mixed-valence complexes whose spin states are situated in the spin-crossover region, it is expected that a cooperative phenomenon coupled with spin and charge takes place between neighboring metal ions in order to minimize the free energy in the whole system. From this viewpoint, we have investigated the charge transfer phase transition, which is a conjugated phenomenon coupled with spin and charge, (n-C_nH_<2n+1>)_4N[Fe^<II>Fe^<III> (dto)_3] (n=3-6,dto=C_2O_2S_2). The charge transfer phase transition takes place for n = 3 and 4, while it does not take place between 300 K and 4 K for n=5 and 6. In order to reveal the dynamics of the charge transfer phase transition, we have investigated muon spin relaxation (μSR) for n - 3 and 5. In the temperature range of the charge transfer phase transition for n = 3, an anomalous enhancement of the dynamic muon-spin depolarization rate with thermal hysteresis loop was observed at around 80 K in the temperature dependence of the depol … More arization rate. The origin of this anomaly has been successfully assigned to the dynamic process of electron-transfer between Fe^<II> and Fe^<III> and its frequency has been estimated from LF-μSR to be about the order of 0.1 MHz. This result is the first observation of dynamical electron transfer process by μSR technique for such mixed valence complexes.Moreover, in order to control the magnetic properties and the electronic state in the dto-bridged iron mixed-valence system by means of photo-irradiation, we have synthesized a photo-sensitive organic-inorganic hybrid system, (SP)[Fe^<II>Fe^<III>(dto)_3] (SP = spiropyran), and investigated the photo-induced effect on the magnetic properties by the measurements of magnetic susceptibility, UV-vis and ^<57>Fe Mossbauer spectra. The UV irradiation changes the structure of spiropyran from the closed form to the open one in (SP)[Fe^<II>Fe^<III> (dto)_3], which induces the charge transfer phase transition in the two-dimensional honeycomb network structure of [Fe^<II>Fe^<III>(dto)_3]., and changes the ferromagnetic transition temperature. Less

在自旋态位于自旋交叉区域的混合价配合物的情况下，预计相邻金属离子之间会发生与自旋和电荷耦合的协同现象，以使整个系统中的自由能最小化。从这个角度出发，我们研究了电荷转移相变，这是一种与自旋和电荷耦合的共轭现象，(n-C_nH_<2n+1>)_4N[Fe^<II>Fe^<III> (dto)_3 ] (n=3-6,dto=C_2O_2S_2) 当 n = 3 和 4 时，发生电荷转移相变，而当 n=5 和 6 时，在 300 K 和 4 K 之间不发生电荷转移相变。为了研究电荷转移相变的动力学，我们研究了 n - 3 和 5 的 μ 子自旋弛豫 (μSR)。在 n = 3 的电荷转移相变温度范围内，在 80 K 左右观察到具有热滞回线的动态 μ 子自旋去极化率，这种异常的起源已成功归因于 Fe^<II 之间电子转移的动态过程。 > 和 Fe^<III>，其频率根据 LF-μSR 估计约为 0.1 MHz。该结果是首次通过 μSR 技术观察到此类混合的动态电子转移过程。此外，为了通过光照射来控制dto桥联铁混合价体系中的磁性和电子态，我们合成了一种光敏有机-无机杂化体系（SP）[ Fe^<II>Fe^<III>(dto)_3] (SP = 螺吡喃)，并通过磁化率、UV-vis 和磁化率的测量研究了光致对磁性能的影响。 ^<57>Fe穆斯堡尔谱。紫外线照射将螺吡喃的结构从封闭形式改变为开放形式(SP)[Fe^<II>Fe^<III>(dto)_3]，从而诱导电荷转移。 [Fe^<II>Fe^<III>(dto)_3].的二维蜂窝网络结构中发生相变，并且铁磁转变温度变化较小。