NER: Nanostructures from Magnetic Centers and Liquid Crystal Linkers

NER：来自磁中心和液晶连接器的纳米结构

• 批准号: 0304273
• 负责人: Sarah Stoll
• 金额: $ 9.94万
• 依托单位: Georgetown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0304273&HistoricalAwards=false
• 关键词: NER; Nanostructures; Magnetic; Centers; Liquid

This project seeks to synthesize nanoscale structures based on inorganic and organic components likely to combine to give interesting magnetic properties, and to identify assembly methods that confer nanostructural control. The inorganic centers, nanoparticles of magnetic semiconductors, will be explored for unusual magnetic properties, size dependent magnetic ordering and quantum control. Lyotropic liquid crystals will be tested as organic linkers for their utility in fabricating nanoscale frameworks. Adapting procedures developed for nanoparticles of semiconductors such as CdS or CdSe, europium chalcogenide EuQ (Q = O, S, Se, Te) nanoparticles will be synthesized. The europium chalcogenides are of interest because they exhibit magnetic properties strongly dependent on the electronic band gap. Given what is known about the effect of particle size on the band gap of semiconductors, size selection of these nanoparticles should determine the magnetic properties. The organic linkers, self-assembled momnolayers ( SAMs), polyanions and lyotropic liquid crystals, are chosen for their ability to self organize, and provide sites of attachment for inorganic clusters. In particular, the lyotropic liquid crystals form a variety of structures, lamellar films, hexagonally packed microtubules and micelles which can be locked into place using polymerizable monomers . The test case cluster is the manganese oxo cluster, known as Mn-12 ([Mn12O12HAc162HAc2H2O] where Ac = acetate). This cluster has a core of metal-oxygen atoms surrounded by a coating of acetate groups. By ligand exchanging acetate groups from the cluster with carboxylates bound to a surface, the Mn-12 can be patterned onto substrates. The advantage of the lyotropic liquid crystals is they contain a surface of carboxylic acids, where Mn-12 may be attached. %%%The study of magnetic semiconductor nanoparticles represents an original and fundamentally new direction. In addition to expanding the knowledge of molecular magnetic materials, the study of these nanoparticles will provide a unique example of how magnetic phenomena evolves from molecules to bulk solid materials. The use of novel organic linkers using lyotropic liquid crystals, may provide an ideal framework for organizing magnetic clusters. Method for organizing material on the nanometer length scale is crucial to the development of nanoscale science that will directly impact technologically "hot" areas such as magnetic information. Students trained in the areas of synthesis, characterization, and applications of nanoscience and engineering, which are prioroity areas of high interest to industry, are very competitive in the industrial and academic job market. This project is co-funded by the Chemistry Division and the Division of Materials Research.***

该项目旨在合成基于无机和有机成分的纳米级结构，这些成分可能结合起来产生有趣的磁性，并确定赋予纳米结构控制的组装方法。 无机中心、磁性半导体纳米粒子将被探索其不寻常的磁性、尺寸依赖的磁性排序和量子控制。 溶致液晶将作为有机连接剂在制造纳米级框架中进行测试。 将合成针对半导体纳米颗粒（例如 CdS 或 CdSe）、铕硫族化物 EuQ（Q = O、S、Se、Te）纳米颗粒开发的适应程序。 铕硫属化物之所以引起人们的兴趣，是因为它们表现出强烈依赖于电子带隙的磁性。 鉴于已知颗粒尺寸对半导体带隙的影响，这些纳米颗粒的尺寸选择应决定磁性。 选择有机连接体、自组装单层 (SAM)、聚阴离子和溶致液晶是因为它们具有自组织能力，并为无机簇提供附着位点。 特别是，溶致液晶形成各种结构、层状薄膜、六边形堆积的微管和胶束，这些结构可以使用可聚合单体锁定到位。 测试用例簇是锰氧簇，称为 Mn-12（[Mn12O12HAc162HAc2H2O]，其中 Ac = 乙酸盐）。 该簇有一个金属氧原子核心，周围有一层乙酸基团。 通过配体将簇中的乙酸基团与表面结合的羧酸盐进行交换，Mn-12 可以在基底上形成图案。 溶致液晶的优点是它们含有羧酸表面，其中可以附着Mn-12。 %%%磁性半导体纳米颗粒的研究代表了一个原创的、全新的方向。 除了扩展分子磁性材料的知识之外，对这些纳米颗粒的研究还将提供一个独特的例子，说明磁性现象如何从分子演变为块状固体材料。 使用溶致液晶的新型有机连接体可以为组织磁性簇提供理想的框架。 在纳米长度尺度上组织材料的方法对于纳米科学的发展至关重要，这将直接影响磁信息等技术“热点”领域。 在纳米科学和工程的合成、表征和应用领域接受培训的学生是工业界高度关注的优先领域，在工业和学术就业市场上非常有竞争力。该项目由化学部和材料研究部共同资助。***