NER: Nanostructures from Magnetic Centers and Liquid Crystal Linkers

该项目旨在合成基于无机和有机成分的纳米结构，这些成分可能结合在一起，以提供有趣的磁性，并确定赋予纳米结构控制的组装方法。无机中心，磁性半导体的纳米颗粒，将被探索不寻常的磁性，大小相关的磁性有序和量子控制。溶致液晶将作为有机连接物在制造纳米级框架中的效用进行测试。采用开发的用于半导体纳米粒子的方法，如硫化镉或镉硒，将合成出EuQ(Q=O，S，Se，Te)纳米粒子。Eu的硫系化合物是很有兴趣的，因为它们表现出强烈依赖于电子带隙的磁性。鉴于已知的粒子尺寸对半导体禁带的影响，这些纳米粒子的尺寸选择应该决定其磁性。有机连接物，自组装膜(SAM)，多阴离子和溶致液晶，因为它们的自组织能力而被选择，并为无机簇合物提供附着位置。特别是，溶致液晶形成了各种结构，层状膜、六角排列的微管和胶束，可以使用可聚合单体将其锁定在适当的位置。测试用例簇是锰氧簇，称为Mn-12([Mn12O12HAc162HAc2H2O]，其中ac=乙酸酯)。这个星团的核心是金属氧原子，周围包裹着一层醋酸酯基团。通过与表面结合的羧酸盐交换簇合物中的醋酸基，可以将Mn-12图案化到衬底上。溶致液晶的优点是它们含有羧酸的表面，其中可能附着着Mn-12。磁性半导体纳米粒子的研究代表了一个原创性和根本性的新方向。除了扩展分子磁性材料的知识外，对这些纳米颗粒的研究将提供一个独特的例子，说明磁性现象如何从分子进化到块状固体材料。使用溶致液晶的新型有机连接物的使用可以提供组织磁性团簇的理想框架。纳米尺度材料的组织方法对纳米尺度科学的发展至关重要，纳米尺度科学将直接影响磁信息等技术“热门”领域。在纳米科学和工程的合成、表征和应用领域接受过培训的学生，在工业和学术就业市场上具有很强的竞争力。本项目由化学部和材料研究部共同资助。*

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.***