Doping Molecular Crystals

技术摘要在材料研究部固态和材料化学计划的支持下，固溶体的形成被探索为调节亚稳态分子晶体相的物理性质(如热稳定性、溶解性、硬度)的一种手段。制备了二水尿酸(UAD)和各种无机、分子和聚合物组分的固溶体。使用一系列互补技术分析纯材料和固体溶液的物理性质，总的目标是建立结构与性质的关联。原位原子力显微镜提供了对固溶体生长机制的分子水平的洞察。通过纳米压痕研究，可以比较纯UAD、掺杂UAD和更稳定的无水尿酸相的机械性能。将固溶体策略应用于更广泛的已知在无水和水合两种相中结晶的分子组分，使人们能够更全面地了解通过固溶体形成可以在有机体系中实现的性质变化的真实范围。用X射线衍射、热分析和显微分析方法比较了纯晶体材料和掺杂晶体材料的物理性质。通过水蒸气吸附实验比较了纯和掺杂亚稳无水相的潮解行为。非技术摘要许多行业，如制药、食品、农用化学品和能源，都依赖于有机分子晶体。这项研究旨在加深我们对晶体的物理性质(如稳定性、溶解性、吸水或释水、机械强度)与其三维结构之间的关系的了解。斯威夫特教授还与国家实验室的研究人员建立了合作关系。这项合作研究为研究生、本科生和高中生提供了宝贵的跨学科培训机会。

Technical AbstractIn this project supported by the Solid State and Materials Chemistry Program of the Division of Materials Research, the formation of solid solutions is explored as a means to tune the physical properties (e.g. thermal stability, solubility, hardness) of metastable molecular crystal phases. Solid solutions of uric acid dihydrate (UAD) and assorted inorganic, molecular and polymeric components are prepared. The physical properties of pure materials and solid solutions are analyzed using a battery of complementary techniques with the overall goal to establish structure-properties correlations. In situ AFM provides molecular-level insight into the growth mechanisms of solid solutions. Nanoindentation studies enable comparison of the mechanical properties of pure UAD, doped UAD and the more stable anhydrous uric acid phase. The application of solid solution strategies to a broader class of molecular components known to crystallize in both anhydrous and hydrated phases enables a fuller understanding of the true scope of property changes that can be achieved in organic systems through solid solution formation. X-ray diffraction, thermal analysis, and microscopy methods are used to compare the physical properties of pure and doped crystalline materials. Vapor sorption experiments are used to compare the deliquescence behavior of pure and doped metastable anhydrous phases. Non-technical AbstractMany industries such as pharmaceuticals, foods, agrochemicals and energetics rely on organic molecular crystals. This research aims to increase our understanding of the relationship between physical properties (e.g. stability, solubility, water uptake or release, mechanical strength) and the 3D structure of the crystal. Prof. Swift additionally establishes a collaboration with researchers at a National Lab facility. This collaborative research provides valuable interdisciplinary training opportunities for graduate, undergraduate and high school students.