Multiple structural transformations coupled with switchable magnetic and dielectric responses in an amphidynamic crystal of 4′-tert-butylbenzylpyridinium bis(maleonitriledithiolate)nickelate

Multifunctional materials that display different physical properties in a single phase can be utilized in multifunctional devices that are capable of performing more than one task simultaneously. In this study, we synthesized a novel multiple phase transition charge transfer salt [4′-tBu-BzPy][Ni(mnt)₂] (4′-tBu-BzPy⁺ = 4′-tert-butylbenzyl-pyridinium, mnt^2- = maleonitriledithiolate) by incorporating a tert-butyl group to control the rotational dynamics in the crystal and to pre-program the amphidynamic [Ni(mnt)₂]^- magnetic lattice. This salt experienced a two-step structural transformation to give three separate high, immediate and low temperature phases. Interestingly, two structural transformations were coupled to both hysteretic magnetic phase transitions at 187/192 K and 94/96 K, and to dielectric anomalies. These results will assist the design and preparation of novel multiple phase-transition materials harboring technologically important magnetic and dielectric properties.