Evaluating the high-pressure structural response and crystal lattice interactions of the magnetically-bistable organic radical TTTA

Abstract

Magnetic bistability has previously been observed and evaluated in an organic thiazyl radical 1,3,5 triathia 2,4,6-triazapentalenyl (TTTA). Herein, the structure-pressure response of TTTA has been evaluated by X-ray diffraction, where...

Room-Temperature Magnetic Bistability in a Salt of Organic Radical Ions

“…Stable organic radicals that exhibit a hysteretic response to an external stimulus (temperature, light, or pressure) display physical properties such as magnetic bistability that are promising for use in nanotechnology devices. − Neutral organic π radicals have been extensively studied because their electron-exchange interactions can lead to dynamic structures weakly coupled; in which interconversion between radicals ( S = 1 / 2 ) and π or σ dimers ( S = 0) is possible. − These cooperative solid-state interactions between different centers allow variation of the crystalline lattice such that hysteretic first-order phase transitions can arise. While this parallels the well-known spin-crossover (SCO) phenomena of transition metal ion complexes, radical-based magnetically bistable systems are comparatively rare.…”

“…While this parallels the well-known spin-crossover (SCO) phenomena of transition metal ion complexes, radical-based magnetically bistable systems are comparatively rare. The neutral heterocyclic thiazyl π radicals are among the most successful class of radicals in this regard, ,,,− with only a few examples of nitroxides ,− , triazinyl and spirophenalenyl derivatives known to be bistable. In these examples, magnetic switching typically occurs by breaking/forming antiferromagnetically coupled π dimers, although examples of weakly bonded σ dimers have also been reported. , …”

Magnetic Bistability in an Organic Radical-Based Charge Transfer Cocrystal

“…Molecular systems exhibiting magnetic bistability, i.e., two interchangeable stable magnetic phases that respond to external stimulus such as light, pressure, or temperature, have been of substantial interest for a variety of nanotechnological applications such as thermal sensors, switching units, information storage media, and so on. − Particularly, such bistable materials based on stable organic radicals are extremely appealing because they manifest not only the desired hysteretic responses that are traditionally considered to be exclusive to transition-metal-based spin-crossover (SCO) complexes but also the unique advantages of using versatile organic synthetic tools to facilely modulate their chemical structures and related properties including molecular packing patterns, spin states, electronic structures, charge distributions, etc. Therefore, accompanied by the extensive efforts devoted to the magnetic property studies of organic radicals over the past several decades, a body of magnetic bistable materials have been developed based on both charge neutral and ionic radicals, − among which the seminal examples include the thiazyl-, − spirophenalenyl-, nitroxide-, − and dithiadiazolyl-based neutral radicals, as well as several charged (di)­radical ion salts. , However, when compared to the well-known inorganic transition metal ion complex-based bistable materials enabled by SCO, currently the reported amounts of radicals-based all-organic materials with controlled magnetic bistability are far rarer, − imposing severe restrictions on their practical applications. Therefore, it is still imperative, but highly challenging, to further develop novel organic-radical-based bistable material systems with informative illustrations of how the chemical/electronic structures of these materials affect their magnetic bistable behaviors.…”