Thorarinsdottir Agnes E, Harris T David
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Department of Chemistry, University of California, Berkeley, California 94720, United States.
Chem Rev. 2020 Aug 26;120(16):8716-8789. doi: 10.1021/acs.chemrev.9b00666. Epub 2020 Feb 11.
Metal-organic frameworks represent the ultimate chemical platform on which to develop a new generation of designer magnets. In contrast to the inorganic solids that have dominated permanent magnet technology for decades, metal-organic frameworks offer numerous advantages, most notably the nearly infinite chemical space through which to synthesize predesigned and tunable structures with controllable properties. Moreover, the presence of a rigid, crystalline structure based on organic linkers enables the potential for permanent porosity and postsynthetic chemical modification of the inorganic and organic components. Despite these attributes, the realization of metal-organic magnets with high ordering temperatures represents a formidable challenge, owing largely to the typically weak magnetic exchange coupling mediated through organic linkers. Nevertheless, recent years have seen a number of exciting advances involving frameworks based on a wide range of metal ions and organic linkers. This review provides a survey of structurally characterized metal-organic frameworks that have been shown to exhibit magnetic order. Section 1 outlines the need for new magnets and the potential role of metal-organic frameworks toward that end, and it briefly introduces the classes of magnets and the experimental methods used to characterize them. Section 2 describes early milestones and key advances in metal-organic magnet research that laid the foundation for structurally characterized metal-organic framework magnets. Sections 3 and 4 then outline the literature of metal-organic framework magnets based on diamagnetic and radical organic linkers, respectively. Finally, Section 5 concludes with some potential strategies for increasing the ordering temperatures of metal-organic framework magnets while maintaining structural integrity and additional function.
金属有机框架代表了开发新一代定制磁体的终极化学平台。与主导永磁技术数十年的无机固体不同，金属有机框架具有众多优势，最显著的是其近乎无限的化学空间，可用于合成具有可控性质的预先设计和可调谐结构。此外，基于有机连接体的刚性晶体结构的存在使得无机和有机组分具有永久孔隙率和合成后化学修饰的潜力。尽管具有这些特性，但实现具有高有序温度的金属有机磁体仍然是一项艰巨的挑战，这主要是由于通过有机连接体介导的典型弱磁交换耦合。然而，近年来已经取得了一些令人兴奋的进展，涉及基于多种金属离子和有机连接体的框架。本文综述了已被证明呈现磁有序的结构表征金属有机框架。第1节概述了对新型磁体的需求以及金属有机框架在这方面的潜在作用，并简要介绍了磁体的类别以及用于表征它们的实验方法。第2节描述了金属有机磁体研究中的早期里程碑和关键进展，这些为结构表征的金属有机框架磁体奠定了基础。然后，第3节和第4节分别概述了基于抗磁性和自由基有机连接体的金属有机框架磁体的文献。最后，第5节总结了一些在保持结构完整性和附加功能的同时提高金属有机框架磁体有序温度的潜在策略。
