Transparent, Superparamagnetic KCo[FeIII(CN)6]–Silica Nanocomposites with Tunable Photomagnetism
Transparent, Superparamagnetic KCo[FeIII(CN)6]–Silica Nanocomposites with Tunable Photomagnetism
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DOI：
10.1002/anie.200250409
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发表时间：
2003-06
影响因子：
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通讯作者：
Joshua G. Moore;E. Lochner;C. Ramsey;N. Dalal;A. Stiegman
中科院分区：
文献类型：
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作者：
Joshua G. Moore;E. Lochner;C. Ramsey;N. Dalal;A. Stiegman
基于普鲁士蓝类过渡金属氰化物配合物的分子磁体引起了人们极大的兴趣。[1]这些材料的开创性工作已经实现了广泛的铁磁和亚铁磁固体，居里点范围从低温到室温以上。[2，3]在含有表现出单畴磁性行为的纳米级磁性颗粒的纳米复合结构的开发中也存在平行的兴趣。[4-6]磁性纳米复合材料的研究是由其新颖的性能和作为新的磁性，光学和电子材料的潜力驱动的。然而，除了一个例外[7]，普鲁士蓝类磁性材料还没有被制成纳米颗粒，并且据我们所知，还没有将它们纳入复合结构的报道。在这里，我们报告了一种新的纳米复合材料的制造含有KxCoIIy [FeIII（CN）6] z，普鲁士蓝的铁磁类似物，在多孔二氧化硅基质。这种材料是由一个控制的多组分溶胶-凝胶合成，其中普鲁士蓝类似物的沉淀被逮捕在纳米尺度的二氧化硅网络的凝胶化。所得到的材料是均匀的，光学透明的，并表现出超顺磁性和可调的光磁行为。我们相信，这项研究提出了一种新的方法，利用普鲁士蓝类磁性材料在先进的光学和磁学application.Homogeneous二氧化硅干凝胶含有氰化物桥接的CoII/FeIII中心的过渡金属组分的合成过程中的溶液相结合。为了获得均匀的材料可重复的，条件进行了优化的水量和浓度和摩尔比的钴II和铁氰化物通过以下先前开发的程序。[8，9]在优化的制备中，将硝酸钴溶解在甲醇中并加入到正硅酸四甲酯中。向该溶液中加入铁氰化钾水溶液以得到1：1的Co：Fe摩尔比。在混合时，溶液变成深紫色，这表明混合价络合物的形成。在浓度高达0.03摩尔%的总金属对硅（Fe+
There has been considerable interest in molecular magnets based on the Prussian blue class of transition-metal cyanide complexes.[1] Pioneering work on these materials has realized a broad range of ferro-and ferrimagnetic solids with Curie points ranging from cryogenic to above room temperature.[2, 3] A parallel interest also exists in the development of nanocomposite structures containing nanoscale magnetic particles exhibiting single-domain magnetic behavior.[4–6] Investigations of magnetic nanocomposites is driven by their novel properties and their potential as new magnetic, optical, and electronic materials. With one exception,[7] however, the Prussian blue class of magnetic materials has not been produced as nanoparticles, and, to the best of our knowledge, there have been no reports of their incorporation into composite structures. Herein we report the fabrication of a new nanocomposite material containing KxCoII y [FeIII (CN) 6] z, a ferromagnetic analogue of Prussian blue, in a porous silica matrix. This material is made by a controlled multicomponent sol–gel synthesis in which the precipitation of the Prussian blue analogue is arrested at nanoscale dimensions by gelation of the silica network. The resulting materials are homogeneous, optically transparent, and exhibit superparamagnetic and tunable photomagnetic behavior. We believe that this study suggests a new approach for utilizing the Prussian blue class of magnetic materials in advanced optical and magnetic applications.Homogeneous silica xerogels containing cyanide-bridged CoII/FeIII centers were made by incorporation of both transition-metal components during the solution phase of the synthesis. To obtain homogeneous materials reproducibly, conditions were optimized for the amount of water and the concentration and molar ratio of CoII and ferricyanide by following previously developed procedures.[8, 9] In the optimized preparation, CoII nitrate was dissolved in methanol and added to tetramethylorthosilicate. Aqueous potassium ferricyanide was added to this solution to give a 1: 1 Co: Fe molar ratio. Upon mixing, the solution turns dark purple, which suggests the formation of the mixed-valence complex. At concentrations up to 0.03 mol% total-metal to silicon (Fe+