Direct Imaging of Isolated Single-Molecule Magnets in Metal–Organic Frameworks

Abstract

Practical applications involving the magnetic bistability of single-molecule magnets (SMMs) for next-generation computer technologies require nanostructuring, organization, and protection of nanoscale materials in two- or three-dimensional networks, to enable read-and-write processes. Owing to their porous nature and structural long-range order, metal–organic frameworks (MOFs) have been proposed as hosts to facilitate these efforts. Although probing the channels of MOF composites using indirect methods is well established, the use of direct methods to elucidate fundamental structural information is still lacking. Herein we report the direct imaging of SMMs encapsulated in a mesoporous MOF matrix using high-resolution transmission electron microscopy. These images deliver, for the first time, direct and unambiguous evidence to support the adsorption of molecular guests within the porous host. Bulk magnetic measurements further support the successful nanostructuring of SMMs. The preparation of the first magnetic composite thin films of this kind furthers the development of molecular spintronics.

Cryo-EM Structures of Atomic Surfaces and Host-Guest Chemistry in Metal-Organic Frameworks

“…8 Interactions between the host framework and guest molecule are central to such applications but are poorly understood at the molecular level. Although transmission electron microscopy (TEM) has been used to study the empty MOF framework, [9][10][11][12][13][14] imaging sub-nanometer guest insertion within the MOFs is still challenging. Of note, a recent study successfully imaged guest single-molecule magnets via TEM, but at relatively low dosage and large molecular size (> 1 nm) 14 .…”

Unraveling Structure and Dynamics in Porous Frameworks via Advanced In Situ Characterization Techniques

“…In the following works authors could image even defects and their evolution in UiO-66 structure, [154] but also directly "see" the single molecular magnet molecules in the MOF pores [155] or directly look into the mesopores of MIL-101(Cr) structure. [156] Although a number of publications are reported on in situ liquid and solid-gas cells for TEM, these were not yet applied on the beam-sensitive nanoporous materials.…”

“…In the following works authors could image even defects and their evolution in UiO‐66 structure, but also directly “see” the single molecular magnet molecules in the MOF pores or directly look into the mesopores of MIL‐101(Cr) structure …”

Varying the Dimensionality of Cu(II)-Based Coordination Polymers Through Solvent Influence

“…Metal-organic frameworks (MOFs)/coordination polymers (CPs) and zeotypes are currently of great interest due to their potential use in a wide range of applications from gas storage to carbon capture materials [1][2][3][4] and catalysis [5,6] to semiconductors [7][8][9]. These can also demonstrate interesting properties in the field of molecular magnetism [10][11][12][13][14][15]. The general design principle for MOFs/CPs is to combine two building blocks: a node, which is often a metal center or polymetallic cluster, and an organic linker.…”