Metallogels: a novel approach for the nanostructuration of single-chain magnets

In this study we demonstrate that single-chain magnets (SCMs) can be assembled in gel phase and transferred intact on surface. We take advantage of a family of SCMs based on Tb-III ions and nitronyl-nitroxides radicals functionalized with short alkyl chains known to form crystalline supramolecular nanotubes interacting with heptane acting as crystallizing solvent. When the radicals are functionalized with long aliphatic chains a robust gel is formed with similar structural and functional properties respect to its crystalline parent. Indeed, a small-angle X-ray scattering (SAXS) study unambiguously demonstrates that the gel is made of supramolecular nanotubes: the high stability of the gel allows the determination from SAXS data of precise nanotube metrics such as diameter, helical pitch and monoclinic cell of the folded 2D crystal lattice along the tube direction. Additionally, static and dynamic magnetic investigations show the persistence of the SCM behavior in the metallogel. Last, on-surface gelation provides thick films as well as sub-monolayer deposits of supramolecular nanotubes on surface as evidenced by atomic force microscopy (AFM) observations. This paves the road toward magnetic materials and devices made of SCMs profiting of their isolation on surface as individual chains.

Automated summary

This study demonstrates the assembly and transfer of single-chain magnets (SCMs) in the gel phase. SCMs based on Tb-III ions and nitronyl-nitroxides radicals with short alkyl chains can form crystalline supramolecular nanotubes interacting with heptane to create a robust gel. The gel is composed of supramolecular nanotubes, as confirmed by small-angle X-ray scattering, and exhibits SCM behavior in magnetism. Gelation on the surface allows for the deposition of supramolecular nanotubes as thick films or sub-monolayers.