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.