Supramolecular Architecture of Molecular-Level-Ordered 1,1′-Ferrocenedicarboxylic Acid with Poly(4-vinylpyridine) for Bulk Magnetic Coupling

Abstract

Molecular-level ordering provides a powerful approach to enhancing the properties of materials. However, the precise arrangement of molecules in a bulk material is a considerable challenge. To overcome such limitations, hydrogen bonding-directed self-assembly has drawn a lot of attention due to its facile nature in controlling molecular-level order. In this study, we report ordering of the magnetic Fe centers achieved through hydrogen bonding between poly(4-vinylpyridine) (P4VP, MW 60 kDa) and 1,1′-ferrocenedicarboxylic acid (FDA). Co-dissolving P4VP and FDA in dry methanol leads to P4VP–FDA showing an unprecedented degree of order for both FDA and the polymer chain. Such an event of mutual assistance between a dicarboxylic acid and a high molecular weight polymer chain in building the ordered supramolecular architecture is rare. FDA is uniformly distributed in an ordered polymer matrix, with each Fe center in P4VP–FDA linked at the molecular-level through polymeric bridges in a face-centered cubic structure. The P4VP–FDA in the bulk form show a large enhancement of magnetic moment with a paramagnetic resonance and asymmetric current–voltage characteristics similar to the properties of electrode–FDA–electrode architecture.