CAREER: Solid-State and Materials Chemistry applicable to Titanean Model Planetary Ices

在材料研究部固态和材料化学项目的支持下，首席研究员和他的研究小组对一些最小有机分子的结晶和固相进行了实验研究。这些化学物质，如苯和乙腈，在工业和日常生活中经常被用作液体溶剂和/或燃料，但它们也在土星冰冷的卫星土卫六的大气中产生。在降雨的作用下，它们降落在土卫六表面，在那里结晶成行星冰。令人惊讶的是，关于这些最小的有机化合物的固态和材料化学有许多悬而未决的问题，这些化合物与地球上的物质和土卫六上的矿物质有关。这个NSF CAREER项目包括固态结构的详细实验表征和这些材料系统的组成，这些材料系统由两个或多个单独的分子组分组成，结晶为具有新性能的一种材料。在这方面，特别有趣的是发现和设计新的低温热膨胀材料（物理尺寸在加热和冷却时急剧变化的固体），以及可用于合成其他功能固态材料的材料。对小分子和益生元分子自我组装成有机矿物和（行星）冰的研究，也与美国国家科学基金会十大构想中的两个有关：宇宙之窗和理解生命规则；通过低温功能材料的设计，这项研究与10大创意中的另一个联系在一起：探索新北极。随着实验研究，这个NSF职业奖教育新一代的材料科学家，并装备他们的知识和技能，以解决材料表征具有挑战性和长期存在的问题。在期刊封面艺术和图形内容设计表的帮助下，高中生开始参与STEM活动，并可能有动力从事STEM职业。该奖项由美国国家科学基金会材料研究部固态与材料化学项目支持，重点阐明由最小有机分子组成的基本相关多组分有机系统的结构和组成，如苯、吡啶、乙腈、丙腈、丁腈等。这项研究在一定程度上受到了最近结束的卡西尼-惠更斯任务的推动，该任务揭示了土星卫星泰坦的表面蕴藏着大量的小有机分子，这些分子凝固并结晶为行星冰。该项目解决了结构和组成知识以及对最小有机系统的理解方面的主要空白。最值得注意的是，这些体系的二元和三元相图还未被充分探索，其中一些的晶体结构在被发现几个世纪后仍然未知。本研究建立了这些多组分体系的相平衡，并通过x射线和中子衍射和光谱学、拉曼光谱、红外和中子光谱以及量热技术，对它们的晶体、局部和动态结构进行了详细的结构描述。所获得的关于这些系统的结构和组成的知识为设计和开发新的功能材料开辟了大量的可能性，例如巨大的热膨胀特性。这种可扩展性可以在低温应用的模块化热膨胀材料的设计中加以利用。这些分子在晶格中的独特排列也允许前所未有的固态反应性和合成具有修饰或功能化石墨烯或金刚石结构的多组分扩展固体。这些扩展的固体材料在环境条件下有无数的潜在应用。NSF CAREER奖的教育部分有助于培养新一代材料研究人员，使他们具备从粉末衍射数据中解决晶体结构问题的知识。此外，主要研究者在封面艺术和图形内容设计表的帮助下吸引高中生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYWith this NSF CAREER award, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, the principal investigator and his research group carry out experimental research on the crystallization and solid phases of some of the smallest organic molecules. Such chemicals, like benzene and acetonitrile, are frequently used as liquid solvents and/or fuels in industry and everyday life, but they are also produced in the atmosphere of Titan, Saturn’s icy moon. Carried by rainfall, they descend on the surface of Titan, where they crystalize as planetary ices. Surprisingly, there are many open questions about the solid-state and materials chemistry of these smallest organic compounds which are relevant as materials on Earth, and minerals on Titan. This NSF CAREER project includes detailed experimental characterization of the solid-state structure and the composition of these materials systems that consist of two or more individual molecular components that crystallize as one material with new properties. Of particular interest, in this regard, is the discovery and design of novel low-temperature thermal expansion materials (solids for which the physical size drastically changes upon heating and cooling), and of materials that can be used for the synthesis of other functional solid-state materials. The studies on the self-assembly of small and prebiotic molecules into organic minerals and (planetary) ices, are also relevant to two of the NSF’s 10 Big Ideas: Windows on the Universe, and Understanding the Rules of Life; and with the design of low-temperature functional materials, the research connects to another of the 10 Big Ideas: Navigating the New Arctic. Along with the experimental research, this NSF CAREER award educates a new generation of materials scientists and equips them with the knowledge and skillset to address challenging and long-standing questions in materials characterization. High-school students become engaged in STEM activities, and possibly motivated to pursue STEM careers, with the help of journal cover art and table of graphical content design.PART 2: TECHNICAL SUMMARYThis NSF CAREER award, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, focuses on elucidating the structure and composition of fundamentally relevant multicomponent organic systems, comprised of the smallest organic molecules, such as benzene, pyridine, acetonitrile, propionitrile, butanenitrile, etc.. This research is in part motivated by the recently concluded Cassini-Huygens mission, which revealed that the surface of Saturn’s moon Titan harbors large inventories of small organic molecules, solidified and crystalized as planetary ices. The project addresses major gaps in the structural and compositional knowledge and understanding of the smallest organic systems. Most notably, the binary and ternary phase diagrams of these systems are vastly underexplored, and the crystal structures of some of them remain unknown, centuries after their discovery. This research establishes the phase equilibria in these multicomponent systems, and provides a detailed structural account on the crystal, local and dynamic structure of their solid-state by employing X-ray and neutron diffraction and spectroscopy, Raman, infrared and neutron spectroscopy, and calorimetric techniques. The obtained knowledge on the structure and composition of these systems opens a plethora of possibilities for the design and development of new functional materials, for example colossal thermal expansion properties. This expansivity can be leveraged in the design of modular thermal expansion materials for low-temperature applications. The unique arrangement of these molecules in the crystal lattice also allows for unprecedented solid-state reactivity and synthesis of multicomponent extended solids with modified or functionalized graphene- or diamond-like structures. These extended solid materials have myriad of potential applications at ambient conditions. The educational segment of this NSF CAREER award contributes to training of the new generation of materials researchers, equipped with the knowledge to solve crystal structures from powder diffraction data. Additionally, the principal investigator engages high-school students with the help of cover art and table of graphical content design.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.