The First High-Temperature Supramolecular Radical Ferroics.

Since the discovery of TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) in 1973, organic radical ferroics attracted widespread interest among the scientific community. However, the relatively low Curie temperature of 287 K and melting point of 311 K severely hinder its application potential. Despite extensive interest, high-temperature radical ferroics have not been found to date. Here, taking advantage of chemical design theory and supramolecular radical chemistry, we successfully designed two high-temperature organic supramolecular radical ferroics [(NH3-TEMPO)([18]crown-6)](ReO4) (1) and [(NH3-TEMPO)([18]crown-6)](ClO4) (2), which can retain the ferroelectricity up to 413 K and 450 K, respectively. To our knowledge, they are both the first supramolecular radical ferroics and unprecedented high-temperature radical ferroics, where the supramolecular component plays a vital role in the stabilization of radical and extending working temperature window. Additionally, both of them can also present the paramagnetism and non-interacting spin moments, as well as excellent piezoelectric and electrostrictive behaviors comparable to that of LiNbO3. This work provides an efficient design strategy for enriching the family of high-temperature radical ferroics, and should inspire further exploration of multi-functional organic ferroics.