Room-temperature magnetism in the crystal of a 1,6-heptadiyne derivative and its processable polymer

Abstract

Room-temperature organic magnetic materials have long been a sought-after but challenging topic. Besides the reported organic-based magnets including pure organic radicals, charge-transfer salts, and coordination polymers, we report a novel and alternative approach to fabricating purely organic/polymeric magnets based on the crystal of a 4-substituted 1,6-diyne (M1) and its polymer (P1). Both the white M1 crystal and the black P1 powder samples exhibit room-temperature magnetism. The saturation magnetization of P1 is about 0.25 emu g⁻¹ and its Curie temperature is higher than 400 K. After repeated recrystallization of M1 and precipitation of P1 to thoroughly remove the metal-catalyst residues, the room-temperature magnetism of M1 and P1 is tentatively assigned to the stable radicals in the solid samples. The results demonstrated in this work suggest an unprecedented strategy to obtain room-temperature organic magnets.