Metal–Organic Frameworks as Platforms for the Controlled Nanostructuring of Single-Molecule Magnets

Abstract

The prototypical single-molecule magnet (SMM) molecule [Mn12O12(O2CCH3)16(OH2)4] was incorporated under mild conditions into a highly porous metal-organic framework (MOF) matrix as a proof of principle for controlled nanostructuring of SMMs. Four independent experiments revealed that the SMM clusters were successfully loaded in the MOF pores, namely synchrotron-based powder diffraction, physisorption analysis, and in-depth magnetic and thermal analyses. The results provide incontrovertible evidence that the magnetic composite, SMM@MOF, combines key SMM properties with the functional properties of MOFs. Most importantly, the incorporated SMMs exhibit a significantly enhanced thermal stability with SMM loading advantageously occurring at the periphery of the bulk MOF crystals with only a single SMM molecule isolated in the transverse direction of the pores.

Magneto-structural correlations in arsenic- and selenium-ligated dysprosium single-molecule magnets

“… 10 Ultimately, therefore, there is a need to understand why certain relaxation processes in SMMs are so facile, and hence to use innovative coordination chemistry to address these processes. To date, successful strategies have included: studying metal ions in high-symmetry coordination environments; 11 – 15 the use of radical bridging ligands to suppress quantum tunnelling of the magnetization (QTM); 16 the use of magnetic dilution to eliminate dipolar exchange interactions; 17 , 18 modification of the crystal field through changes to the inductive effects of the ligand substituents; 19 the assembly of single-ion magnet building blocks into extended SMMs; 20 the synthesis of metal–organic frameworks in which SMMs are used as nodes 21 or loaded into the porous structure; 22 , 23 and the use of 3d–4f exchange interactions to enhance the blocking temperature. 24 …”

MOF-like supramolecular network of Mn3 single-molecule magnets formed by extensive π–π stacking

“…A diamagnetic 3-D mesoporous MOF as a platform to incorporate Mn 12 Ac SMMs was also reported recently [41]. On the other hand, supramolecular networks connected with weak bonds such as hydrogen-bonds or π-π stacking are very rare but would be interesting to study further because despite the molecular origin of the magnetic properties of SMMs, in the solid-state even weak exchange couplings can have significant influence on their magnetic properties.…”

Hidden Transformations of a Crystalline Sponge: Elucidating the Stability of a Highly Porous Three-Dimensional Metal–Organic Framework

“…40 Inspired by these outstanding findings, we were intrigued by the possibility of applying the crystalline sponge method for the soaking of magnetic molecules, thus offering a unique opportunity to carry out magneto-structural correlations. 41 We initially decided to test the crystalline sponge method using MOF 1a, however, during numerous attempts to prepare the parent MOF, we were repeatedly faced with unexpected and striking experimental results, probably influenced by the observed instability of the reported MOF. 34 In order to exploit the full potential of this MOF as a crystalline sponge, it is critical to understand its full physical behavior and stability.…”