Magnetic Control over the Topology of Supramolecular Rod Networks

Understanding and controlling supramolecular polymerization are of fundamental importance to create advanced materials and devices. Many stimuli have been explored in the past decades, but magnetic fields and field gradients have received little attention. This is because magnets do not provide enough magnetic energy to overcome thermal noise at the single molecule level. Here we show that significant changes in network topology of Gd³⁺-decorated supramolecular polymer rods can nevertheless be observed using magnetic fields of order 1 T at room temperature. The structure of the rod networks is influenced during a slow diffusive process over a timescale of hours by the anisotropy of the demagnetizing field. Our approach opens opportunities to control and tune structure formation of many supramolecular and coordination polymers using a variety of rare earth or other paramagnetic ions.