Self-assembled porous materials from cyclic ureas

环状脲自组装多孔材料

• 批准号: 0718171
• 负责人: Linda Shimizu
• 金额: $ 36万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0718171&HistoricalAwards=false
• 关键词: Self; assembled; porous; materials; cyclic

The Organic and Macromolecular Chemistry Program supports the work of Professor Linda Shimizu of the University of South Carolina who will develop homogeneous microporous materials with rationally tunable cavities. These will be used as confined environments for inducing selectivity in reactions, for host/guest chemistry, and for separations. It has been demonstrated that bis-urea macrocycles predictably self-assemble into porous crystals, which contain hollow tubular channels. The assembly is directed by non-covalent interactions, primarily urea-urea hydrogen bonds, and aryl stacking interactions. The initial structure, phenylether bis-urea, proves that this approach is valid, as it assembles as designed into crystals containing into tubular channels filled with acetic acid guests. The guests can be removed from these crystals forming a porous host that display a type 1 gas adsorption isotherm consistent with an open framework microporous material. Recently it has been shown that crystalline phenylether bis-urea binds guest molecules and that these guests can be removed and rebound reversibly, much like zeolites. In fact, crystalline phenylether bis-urea can be used as a container for reactions, promoting highly stereoselective head-to-tail [2+2] photodimerizations of 2-cyclohexenone in high conversion. Focus will be on the synthesis of bis-urea macrocycles from rigid spacers and ureas that upon self-assembly will display a greater range of cavity sizes and interior properties by modulating the size and shape of the spacers. Functional groups can then be added on the interior to tune the reaction environment and will lead to 'tunable' cavities, designed to bind specific guests and catalyze reactions. Also, these porous materials will be investigated as environments for selective photochemical reactions and as catalysts for alcohol dehydration.The funding of this work by the Organic and Macromolecular Chemistry Program will result in new molecular building blocks that predictably self-assemble into tubular supramolecular assemblies and porous solids that have been sought for applications as sensors, templates for directed reactions, as separation and catalyst supports, and for metal sequestering agents. Graduate students trained in this program will receive a broad multidisciplinary background that will empower them to pursue a wide range of scientific careers. This award will support the first research experiences of undergraduates and high school students. This award will also support the enhancement and continuation of a chemistry outreach program that fosters interactions between K-12 students and teachers and skilled scientific researchers. New experiments to meet teacher requests and to relate to science standards will be incorporated.

有机和大分子化学计划支持南卡罗来纳大学的琳达·辛祖（Linda Shimizu）教授的工作，他们将开发具有合理可调腔的同质微孔材料。这些将用作限制环境，以诱导反应，宿主/来宾化学和分离的选择性。已经证明，双幼粒大环可以预见到包含空心管道通道的多孔晶体中。组装由非共价相互作用（主要是尿素 - 尿素氢键和芳基堆叠相互作用）指导。初始结构，苯乙烯双尿素，证明了这种方法是有效的，因为它按照设计成装入装有乙酸客人的管状通道的晶体组装。可以从这些晶体中删除来宾，形成一个多孔宿主，该宿主显示与开放式框架微孔材料一致的1型气体吸附等温线。最近，已经显示出结晶苯乙烯双尿素结合了来宾分子，并且可以像沸石一样删除这些客人并反弹。实际上，晶体苯乙烯双尿素可用作反应的容器，从高转化率中促进2-循环的高度立体选择性的从头到尾[2+2]光构化。焦点将集中在刚性间隔者和尿液中的双尿素大环的合成上，而自组装后将通过调节垫片的大小和形状来显示更大范围的腔尺寸和内部性能。然后可以在内部添加官能团以调整反应环境，并导致“可调”腔，旨在结合特定的客人并催化反应。另外，这些多孔材料将作为选择性光化学反应的环境和酒精脱水的催化剂进行研究。支撑和金属隔离剂。接受该计划的培训的研究生将获得广泛的多学科背景，这将使他们有能力从事各种科学职业。该奖项将支持大学生和高中生的首次研究经历。该奖项还将支持化学外展计划的增强和延续，该计划促进了K-12学生与教师和熟练的科学研究人员之间的互动。将纳入满足教师要求并与科学标准有关的新实验。