Controlled Nucleation and Growth of Molecular Crystals at Molecular Interfaces

分子界面处分子晶体的受控成核和生长

• 批准号: 9408923
• 负责人: Michael Ward
• 金额: $ 61.5万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-15 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9408923&HistoricalAwards=false
• 关键词: Controlled; Nucleation; Growth; Molecular; Crystals

9408923 Ward This research describes strategies for controlled heterogeneous nucleation and growth of organic crystals at molecular interfaces, with emphasis on the use of substrates based on specific crystal faces of molecular crystals, and self-assembled films prepared from organosulfur and organosilane reagents. The proposed work will demonstrate that enhanced nucleation rates, specific growth orientations, and polymorph selectivity can be achieved through the use of properly designed substrates. In the case of molecular crystal substrates, these characteristics will be examined in the context of ledge-directed epitaxial nucleation, in which prenucleation aggregates are stabilized and oriented by interfacial interaction between two low energy planes of the aggregate and a geometrically similar substrate ledge. Organosulfur and organosilane films provide molecular functionality capable of specifically interacting with functional groups of molecules in the prenucleation aggregate. Atomic force microscopy of dynamic, in situ, crystal growth will also be examined. It is anticipated that these studies will lead to greater understanding of the critical factors responsible for nucleation and growth of organic crystals, and the rational design of solid substrates for controlled crystallization of technologically important reagents and materials. %%% Molecular crystals, defined as solids consisting of molecular components assembled in the crystalline state by weak, but numerous intermolecular interactions, exhibit numerous properties of fundamental and technological interest. These include electrical conductivity, superconductivity and ferromagnetism, nonlinear optical behavior, pharmaceutical activity, and photographic sensitizers. The interest in these materials also stems from the ability to rationally control bulk properties through molec ular design, a strategy commonly referred to as "crystal engineering." While there has been considerable study of the intermolecular interactions that direct solid-state packing in molecular crystals, investigations of their nucleation and growth, particularly at the molecular level, has been rather limited. This research describes strategies for controlled heterogeneous nucleation and growth of organic crystals at molecular interfaces, with emphasis on the use of substrates based on specific crystal faces of molecular crystals, and self-assembled films prepared from organosulfur and organosilane reagents. The proposed work will demonstrate that enhanced nucleation rates, specific growth orientations, and polymorph selectivity can be achieved through the use of properly designed substrates. ***

9408923 Ward本研究描述了在分子界面上控制有机晶体非均相成核和生长的策略，重点是基于分子晶体特定晶面的衬底的使用，以及由有机硫和有机硅烷试剂制备的自组装薄膜。提出的工作将证明，通过使用适当设计的底物，可以提高成核率，特定的生长取向和多晶选择性。在分子晶体衬底的情况下，这些特性将在边缘定向外延成核的背景下进行研究，在这种情况下，预成核聚集体通过聚集体的两个低能量平面和几何上相似的衬底边缘之间的界面相互作用来稳定和定向。有机硫和有机硅烷薄膜提供了能够与预成核聚集体中分子官能团特异性相互作用的分子功能。原子力显微镜的动态，在原位，晶体生长也将进行检查。预计这些研究将导致对有机晶体成核和生长的关键因素有更深入的了解，并合理设计用于控制技术上重要试剂和材料结晶的固体基质。分子晶体，被定义为由分子组分通过弱而多的分子间相互作用以结晶状态组合而成的固体，具有许多基础和技术上的兴趣。这些包括电导率、超导性和铁磁性、非线性光学行为、药物活性和照相增敏剂。对这些材料的兴趣还源于通过分子设计合理控制体积特性的能力，这种策略通常被称为“晶体工程”。虽然对分子晶体中直接形成固态的分子间相互作用进行了大量的研究，但对其成核和生长的研究，特别是在分子水平上的研究，却相当有限。本研究描述了在分子界面上控制有机晶体非均相成核和生长的策略，重点是基于分子晶体特定晶面的衬底的使用，以及由有机硫和有机硅烷试剂制备的自组装薄膜。提出的工作将证明，通过使用适当设计的底物，可以提高成核率，特定的生长取向和多晶选择性。＊＊＊