A Crossover of Molecular and Extended Magnetism in Engineered Solids

磁性材料塑造了我们的现代社会，因为它们对可再生能源、电动发动机、传感器和数据存储领域的进步至关重要。有两种类型的磁性材料——由孤立分子组成的分子磁铁和在晶体结构中具有无限化学键框架的扩展固体或流动磁铁。分子磁体具有低温合成和高可调性的特点，但其相互作用弱。扩展固体磁体在有序状态下表现出强的磁相互作用和大的磁矩，但可调性有限。目前的项目重点是通过合成一组独特的杂化化合物来弥合分子磁铁和扩展固体磁铁之间的差距，这些化合物结合了两类磁性材料的优点。在提出的杂化化合物中，可调谐的分子片段将夹在扩展固体磁铁的一维和二维片段之间。了解结构如何决定性能是新兴材料设计的关键步骤。因此，为了在磁性材料的发展中取得重大突破，我们正在建立分子和延伸片段相互作用的结构和性质与所生产材料的磁性之间的基本关系。在该项目的教育部分，化学研究生和本科生在当地小学、爱荷华州立大学科学与工程女性STEM项目和得梅因科学中心参与化学演示，以培养K-12学生和成年人对化学的兴趣。本项目由材料研究部固态与材料化学项目资助。探索影响固体中磁性相互作用的化学因素是开发新型磁性材料的主要步骤之一。目前的固态合成缺乏有机金属化学和配位化学的可预测性和合理性。为了实现磁性材料的高可预测性和合理设计，研究了由间隙配位金属配合物分离的无限铁硫系碎片组成的杂化磁性材料。通过这种方法，强磁相互作用和可调性被分离到杂化材料的两个不同的亚晶格中。该项目使用配位化学方法来调整分子过渡金属胺配合物，这些配合物被纳入或连接到流动磁铁的无限铁硫族化物碎片之间。预计配位配合物的手性和自旋交叉性质将转化为流动的铁硫族碎片。目标杂化体的一个优点是，硫族铁亚晶格中存在的强磁相互作用和大磁矩将放大自旋交叉跃迁的弱磁特征或产生手性磁体。在该项目的教育部分，化学研究生和本科生在当地小学、爱荷华州立大学科学与工程女性STEM项目和得梅因科学中心参与化学演示，以培养K-12学生和成年人对化学的兴趣。本项目由材料研究部固态与材料化学项目资助。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 I: Non-technical SummaryMagnetic materials have shaped our modern society because they are crucial for advances in the fields of renewable energy, electric engines, sensors, and data storage. There are two types of magnetic materials - molecular magnets, composed of isolated molecules, and extended solid or itinerant magnets with infinite frameworks of chemical bonds within the crystal structure. Molecular magnets are appealing due to their synthesis at low temperatures and high tunability but suffer from weak magnetic interactions. In turn, extended solid magnets exhibit strong magnetic interactions and large magnetic moments in the ordered state but have limited tunability. The current project is focused on bridging the gap between molecular and extended solid magnets by synthesizing a unique set of hybrid compounds, which combine advantages of both classes of magnetic materials. In the proposed hybrid compounds, tunable molecular fragments will be sandwiched in between one- and two-dimensional fragments of extended solid magnets. Understanding how structure determines properties is the key step for design of emerging materials. Thus, to achieve significant breakthroughs in the magnetic materials development, we are establishing fundamental relationships between structure and nature of interactions of molecular and extended fragments, and magnetic properties of the produced materials. In the educational component of the project, chemistry graduate and undergraduate students are engaged in chemistry demonstrations at local elementary schools, the Iowa State STEM Program for Women in Science and Engineering, and the Des Moines Science Center to foster interest of K-12 students and adults in chemistry. This project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research.Part II: Technical SummaryExploration of chemical factors that affect magnetic interactions in solids is one of the major steps in the development of novel magnetic materials. Current solid state syntheses lack the predictability and rationality of organometallic and coordination chemistry. To achieve high predictability and rationally design magnetic materials, hybrid magnetic materials comprising infinite Fe-chalcogenide fragments separated by interstitial coordination metal complexes are being developed. In this way, strong magnetic interactions and tunability are segregated into two different sublattices of a hybrid material. The project uses coordination chemistry methodology to tune molecular transition metal amine complexes which are incorporated in between or connected to extended infinite Fe-chalcogenide fragments of itinerant magnets. It is anticipated that chirality and spin-crossover properties of coordination complexes will be translated to the itinerant Fe-chalcogenide fragments. An advantage of the target hybrids is that strong magnetic interactions and large magnetic moments present in the Fe-chalcogenide sublattice will either amplify the weak magnetic signatures of spin-crossover transitions or produce chiral magnets. In the educational component of the project, chemistry graduate and undergraduate students are engaged in chemistry demonstrations at local elementary schools, the Iowa State STEM Program for Women in Science and Engineering, and the Des Moines Science Center to foster interest of K-12 students and adults in chemistry. This project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research.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.