Magnetic Properties of a Polyfluorene Derivative Metallopolymer Containing Neodymium Ions

The magnetic properties of a polyfluorene derivative, {Poly[9,9'-dihexylfluorene-2,7-yl)-3,8-(1,10-phenanthroline)]} and its complexes with neodymium ions are explored and discussed in the light of the macromolecular configuration and photophysical properties. The pristine noncomplexed material is a diamagnetic material, and the introduction of Nd atoms in the polymer leads to a paramagnetic behavior over the entire temperature range. The prominent role of the morphology is demonstrated by comparison of two forms, with different ligands to the metal: one with bulky beta-diketone groups and another with small chorine as ligands. The large groups hinder interchain interaction, whereas the smaller salt forms favored interchain pi-stacking, providing a better interaction of the magnetic field with the polymer backbone, resulting in enhanced magnetic properties. The form with the beta-diketone groups exhibits a paramagnetic behavior whereas the one in the salt form presents ferromagnetic behavior at room temperature. This contribution brings solid confirmation to the importance of interchain interaction in the magnetic properties of conjugated polymers, opening a new way to the obtainment of magnetic conjugated polymers.