Self‐Assembly Synthesis of a [2]Catenane Co^II Single‐Molecule Magnet

Abstract

We describe herein the self‐assembly synthesis of an octanuclear CoII [2]catenane {[Co4(H2L)6]216+} formed by the mechanical interlocking of two {[Co4(H2L)6]8+} rectangles of unprecedented topology. Subtle manipulation of the synthetic conditions allows the isolation of a mixed‐valence [Co2III/Co2II]10+ non‐catenated rectangle. The CoII centers in the [2]catenane exhibit slow relaxation of their magnetic moment, i. e. single‐molecule magnet properties, dominated by quantum tunneling and Raman relaxation processes. This work shows that metallo‐supramolecular chemistry can precisely control the organization of single‐molecule magnets in topologically complex arrangements.

Distinctive features and challenges in catenane chemistry

“…The non-trivial topology of catenanes may offer an interesting structural scaffold for unusual electronic structures and conjugated systems which are implicated in electronic, luminescent and magnetic materials. 102 Strategies for catenane functionalisation and incorporation in extended networks and interfaces such as surfaces, monolayers, thin films, polymers, nanoparticles and metal–organic frameworks (MOFs) will also be necessary for expressing the unique features of catenanes in different materials and interfaces. 103 On the other hand, the good stability of catenanes provided by the mechanical bond not only will allow studies and explorations of short-lived, reactive species that are implicated in catalysis, energy/electron transfer and material research, but also render catenanes particularly suitable for applications in competitive environments such as biological systems, interfaces, devices and other complex matrices.…”

Crystal structure, assembly process, and single-molecule magnet behavior of a triangular prismatic {Co9} cluster

“…S13 †). 37 Unfortunately, no clear opening of a magnetic hysteresis loop was observed at low temperatures (Fig. S14 †).…”

Ni-Centered Coordination-Induced Spin-State Switching Triggered by Electrical Stimulation

“…Molecules exhibiting switchable magnetic properties have been extensively studied over the last few decades in the context of the miniaturization of electronics, sensors, and memory devices. − This particular field of magnetic switching has been the subject of major developments fueled by numerous research activities focused on molecular spin crossover (SCO) materials − and single-molecule magnets. − Most examples described so far are crystalline solids obtained from first-row transition-metal complexes ( d 4 to d 7 ) capable of undergoing spin-state transition as a response to external physical perturbations such as temperature, pressure, and light. ,, From a practical point of view, SCO phenomena are quite often difficult to explain from well-defined molecular events and they are also strongly dependent on cooperativity processes that happen to be enhanced in the solid state and at low temperatures. , SCO systems are therefore usually studied in solid crystals, although recent reports have shown that similar processes can occur in solution and at near-ambient temperatures. ,− …”