Self-Assembled Fibers Containing Stable Organic Radical Moieties: Alignment and Magnetic Properties in Liquid Crystals

Macroscopically oriented stable organic radicals have been obtained by using a liquid–crystalline (LC) gel composed of an l‐isoleucine‐based low molecular weight gelator containing a 2,2,6,6‐tetramethylpiperidine 1‐oxyl moiety. The LC gel has allowed magnetic measurements of the oriented organic radical. The gelator has formed fibrous aggregates in liquid crystals via intermolecular hydrogen bonds. The fibrous aggregates of the radical gelator are formed and oriented on cooling by applying a magnetic field to the mixture of liquid crystals and the gelator. Superconducting quantum interference device (SQUID) measurements have revealed that both oriented and nonoriented fibrous aggregates exhibited antiferromagnetic interactions, in which super‐exchange interaction constant J is estimated as −0.89 cm−1. Liquid–crystalline physical gels of a stable organic radical gelator have been developed. Magnetic field alignment leads to unidirectional formation of fibrous aggregates of the radical gelators in oriented liquid crystals. Magnetic measurements have shown that fiber formation of the organic radical gelators induces antiferromagnetic interaction and the macroscopic alignment structures of fibrils have no effect on the magnetic properties (see figure).