Enhancement of the Curie temperature by isomerization of diarylethene (DAE) for an organic-inorganic hybrid system: Co4(OH)7(DAE)0.5.3H2O.
Enhancement of the Curie temperature by isomerization of diarylethene (DAE) for an organic-inorganic hybrid system: Co4(OH)7(DAE)0.5.3H2O.
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DOI：
10.1021/ic061498u
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发表时间：
2006-11
影响因子：
4.6
通讯作者：
H. Shimizu;M. Okubo;A. Nakamoto;M. Enomoto;N. Kojima
中科院分区：
文献类型：
--
作者：
H. Shimizu;M. Okubo;A. Nakamoto;M. Enomoto;N. Kojima
将有机光致变色分子插入到层状磁性体系中可以提供诸如光磁性等多功能特性。为了构建光敏多功能磁体，通过Co2(OH)3（CH3COO）之间的阴离子交换反应，合成了具有光致变色二乙烯阴离子2,2′-二甲基-3,3′-（全氟环戊烯-1,2-二基）双（苯并[b]噻吩-6-磺酸盐）（DAE）和钴LDHs（层状双氢氧化物）Co4(OH)7(DAE)0.5.3H2O的有机-无机杂化体系。H2O和DAE。在暗光和紫外（313 nm）条件下，分别得到开放和封闭形式的Co4(OH)7(DAE)0.5.3H2O。磁化率测量表明，具有开放和封闭DAE形式的钴LDHs具有铁磁层内和层间相互作用，居里温度分别为TC = 9和20 K。用封闭形式的DAE取代开放形式的DAE作为插层分子，使居里温度从9 K提高到20 K，这是由于封闭形式DAE中的pi电子离域，增强了层间磁相互作用。具有共轭pi电子体系的（E，E）-2,4-己二烯二酸酯的钴LDHs的居里温度（26.0 K）大大高于具有己二烯二酸酯的钴LDHs的居里温度（7.0 K），这一事实有力地支持了嵌入分子中pi电子离域引起的层间磁相互作用的增强。在313 nm的紫外照射下，Co4(OH)7(DAE)0.5.3H2O在固体状态下发生了由开放形态向封闭形态的光异构化，导致了居里温度的提高。
Intercalation of an organic photochromic molecule into layered magnetic systems may provide multifunctional properties such as photomagnetism. To build up a photosensitive multifunctional magnet, an organic-inorganic hybrid system coupled with a photochromic diarylethene anion, 2,2'-dimethyl-3,3'-(perfluorocyclopentene-1,2-diyl)bis(benzo[b]thiophene-6-sulfonate) (DAE), and cobalt LDHs (layered double hydroxides), Co4(OH)7(DAE)0.5.3H2O, was synthesized by the anion exchange reaction between Co2(OH)3(CH3COO).H2O and DAE. In the dark and under UV-irradiated (313 nm) conditions, Co4(OH)7(DAE)0.5.3H2O with open and closed forms of DAE were obtained, respectively. The magnetic susceptibility measurements elucidated ferromagnetic intra- and interlayer interactions and Curie temperatures of TC = 9 and 20 K for cobalt LDHs with the open and closed forms of DAE, respectively. The enhancement of the Curie temperature from 9 to 20 K by substitution of the open form of DAE with the closed form of DAE as an intercalated molecule is attributed to the delocalization of the pi-electrons in the closed form of DAE, which enhances the interlayer magnetic interaction. The enhancement of the interlayer magnetic interaction induced by the delocalization of pi-electrons in intercalated molecules is strongly supported by the fact that the Curie temperature (26.0 K) of cobalt LDHs with (E,E)-2,4-hexadienedioate having a conjugated pi-electron system is enormously higher than that (7.0 K) of the cobalt LDHs with hexanedioate. By UV irradiation at 313 nm, Co4(OH)7(DAE)0.5.3H2O shows the photoisomerization of DAE from the open form to the closed one in the solid state, which leads to the enhancement of Curie temperature.