Control of Charge Transfer Phase Transition and Ferromagnetism by Photoisomerization of Spiropyran for an Organic-Inorganic Hybrid System, (SP)[FeIIFeIII(dto)3] (SP = spiropyran, dto = C2O2S2)
Control of Charge Transfer Phase Transition and Ferromagnetism by Photoisomerization of Spiropyran for an Organic-Inorganic Hybrid System, (SP)[FeIIFeIII(dto)3] (SP = spiropyran, dto = C2O2S2)
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DOI：
10.1021/ja806879a
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发表时间：
2009-01-14
影响因子：
15
通讯作者：
Kojima, Norimichi
中科院分区：
文献类型：
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作者：
Kida, Noriyuki;Hikita, Masanori;Kojima, Norimichi
铁的混合价络合物（n-C3 H7）（4）N[（FeFeIII）-Fe-II（dto）（3）]（dto = C2 O2 S2）在120 K附近出现自旋熵驱动的相变，称为[（FeFeIII）-Fe-II（dto）（3）]（无穷大）（-）中的电荷转移相变，在7 K出现铁磁相变。在[（FeFeIII）-Fe-II（dto）（3）]（无穷大）（-）的二维蜂窝状网络结构中，这些相变显著地依赖于六方环的尺寸。为了利用光辐射调控dto桥联铁混合价体系的磁性和电子态，我们合成了一种光敏有机-无机杂化体系（SP）[（FeFeIII）-Fe-II（dto）（3）]（SP =螺吡喃），并研究了光诱导对磁性的影响。在350 nm紫外光照射下，螺吡喃在500 ~ 600 nm之间出现一个宽吸收带，并随着照射时间的延长而不断增强，说明紫外光照射使螺吡喃的结构由封闭型转变为开放型。螺吡喃的光致变色性使铁磁转变温度从5 K变化到22 K，在2 K时矫顽力从1400 Oe变化到6000 Oe。在此过程中，实现了[（FeFeIII）-Fe-II（dto）（3）]（无穷大）（-）中电荷转移相变与螺吡喃光异构化的协同现象。
Iron mixed-valence complex, (n-C3H7)(4)N[(FeFeIII)-Fe-II(dto)(3)](dto = C2O2S2), shows a spin entropy-driven phase transition called charge transfer phase transition in [(FeFeIII)-Fe-II(dto)(3)](infinity)(-) around 120 K and a ferromagnetic transition at 7 K. These phase transitions remarkably depend on the hexagonal ring size in the two-dimensional honeycomb network structure of [(FeFeIII)-Fe-II(dto)(3)](infinity)(-). In order to control the magnetic properties and the electronic state in the dto-bridged iron mixed-valence system by means of photoirradiation, we have synthesized a photosensitive organic-inorganic hybrid system, (SP)[(FeFeIII)-Fe-II(dto)(3)](SP = spiropyran), and investigated the photoinduced effect on the magnetic properties. Upon UV irradiation at 350 nm, a broad absorption band between 500 and 600 nm appears and continuously increases with the photoirradiation time, which implies that the UV irradiation changes the structure of spiropyran from the closed form to the open one in solid state. The photochromism in spiropyran changes the ferromagnetic transition temperature from 5 to 22 K and the coercive force from 1400 to 6000 Oe at 2 K. In this process, the concerted phenomenon coupled with the charge transfer phase transition in [(FeFeIII)-Fe-II(dto)(3)](infinity)(-) and the photoisomerization of spiropyran is realized.