A Functional Nitroxide Radical Displaying Unique Thermochromism and Magnetic Phase Transition

Matsumoto, Sachiko; Higashiyama, Tsutomu; Akutsu, Hiroki; Nakatsuji, Shin’ichi

doi:10.1002/anie.201104068

Cited by 58 publications

(30 citation statements)

References 15 publications

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“…Functional materials featuring sudden change of their physical and/or chemical properties in response to temperature fluctuation, pressure variation, light, electric/magnetic field, and other external stimuli have attracted great attention over the past decade . Typically, their responsive dynamics involves two distinct states (i.e., bistability) with regard to color, magnetization, electrical resistance, electrical polarization, or other physical properties, giving rise to potential advantages in the applications of sensors, displays, switches, and especially digital memory devices at a digital age .…”

Section: Methodsmentioning

confidence: 99%

A Niccolite Structural Multiferroic Metal–Organic Framework Possessing Four Different Types of Bistability in Response to Dielectric and Magnetic Modulation

et al. 2017

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Multiple switchable physical properties have been demonstrated in one single niccolite structural metal-organic framework, [(CH CH ) NH ][Fe Fe (HCOO) ] (1), including (i) a reversible ferroelastic phase transition triggered by freezing the disordered (CH CH ) NH cations, (ii) a thermally switchable dielectric constant transition accompanied by phase transition, and (iii) thermal and positive magnetic field driven magnetic poles reversal at low temperatures, attributed to different responses of the magnetization of Fe and Fe sublattices to external stimuli. More interestingly, the exchange anisotropy between the two sublattices can also give rise to tunable positive and negative exchange bias fields. Straightforwardly, such diverse demonstrations of bistability in one single material (depending on the specific tuning way) will provide extra freedom and flexibility for the design of switcher devices.

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Section: Methodsmentioning

confidence: 99%

A Niccolite Structural Multiferroic Metal–Organic Framework Possessing Four Different Types of Bistability in Response to Dielectric and Magnetic Modulation

et al. 2017

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“…Many organic radicals also exhibit a reversible conversion between monomers that exhibit S (spin quantum number) = 1/2 and dimers with S = 0, which is accompanied by a change in the system's magnetic properties. This transformation, which involves a change in the spin state of the organic species, is often called spin transition (or spin crossover), although its mechanism is very different from the spin transition of coordination compounds discussed above [37][38][39][40][41][42][43][44][45][46] . Several of these compounds also exhibit thermal hysteresis 39 .…”

Section: Spin Transitionmentioning

confidence: 99%

Dynamic molecular crystals with switchable physical properties

2016

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The development of molecular materials whose physical properties can be controlled by external stimuli - such as light, electric field, temperature, and pressure - has recently attracted much attention owing to their potential applications in molecular devices. There are a number of ways to alter the physical properties of crystalline materials. These include the modulation of the spin and redox states of the crystal's components, or the incorporation within the crystalline lattice of tunable molecules that exhibit stimuli-induced changes in their molecular structure. A switching behaviour can also be induced by changing the molecular orientation of the crystal's components, even in cases where the overall molecular structure is not affected. Controlling intermolecular interactions within a molecular material is also an effective tool to modulate its physical properties. This Review discusses recent advances in the development of such stimuli-responsive, switchable crystalline compounds - referred to here as dynamic molecular crystals - and suggests how different approaches can serve to prepare functional materials.

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“…[1,2] The achievemento f ad eep understandingo ft he features governing the existence of bistability is an ecessary step towards the rational design of new bistable materials.Let us mention that bistability is merely as horterf orm for naming hysteretic spin-switch systems. [6][7][8][9][10][11][12][13][14][15][16][17] Among the purely organic radicals exhibitings pin-switch behavior, the family of dithiazolyl (DTA) neutralr adicals [18,19] is particularly interesting, as it has furnished numerouss witchable materials, some of them presenting hysteretic phaset ransitions, [6, 7, 10-12, 16, 20] and some of them presenting non-hysteretic phase transitions. However,i nh ysteretic spin-switch systems, the LT !HT transition takes place at ad ifferent temperature than that of the HT!LT transition.…”

Section: Introductionmentioning

confidence: 99%

Bistability in Organic Magnetic Materials: A Comparative Study of the Key Differences between Hysteretic and Non‐hysteretic Spin Transitions in Dithiazolyl Radicals

Vela

Reardon

Jakobsche

et al. 2017

Chemistry A European J

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Dithiazolyl (DTA)-based radicals have furnished many examples of organic spin-transition materials, some of them occurring with hysteresis and some others without. Herein, we present a combined computational and experimental study aimed at deciphering the factors controlling the existence or absence of hysteresis by comparing the phase transitions of 4-cyanobenzo-1,3,2-dithiazolyl and 1,3,5-trithia-2,4,6-triazapentalenyl radicals, which are prototypical examples of non-bistable and bistable spin transitions, respectively. Both materials present low-temperature diamagnetic and high-temperature paramagnetic structures, characterized by dimerized (⋅⋅⋅A-A⋅⋅⋅A-A⋅⋅⋅) and regular (⋅⋅⋅A⋅⋅⋅A⋅⋅⋅A⋅⋅⋅A⋅⋅⋅) π-stacks of radicals, respectively. We show that the regular π-stacks are not potential energy minima but average structures arising from a dynamic inter-conversion between two degenerate dimerized configurations: (⋅⋅⋅A-A⋅⋅⋅A-A⋅⋅⋅) ↔(-A⋅⋅⋅A-A⋅⋅⋅A-) . The emergence of this intra-stack dynamics upon heating gives rise to a second-order phase transition that is responsible for the change in the dominant magnetic interactions of the system. This suggests that the promotion of a (⋅⋅⋅A-A⋅⋅⋅A-A⋅⋅⋅) ↔(-A⋅⋅⋅A-A⋅⋅⋅A-) dynamics is a general mechanism for triggering spin transitions in DTA-based materials. Yet, this intra-stack dynamics does not suffice to generate bistability, which also requires a rearrangement of the intermolecular bonds between the π-stacks via a first-order phase transition.

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A Functional Nitroxide Radical Displaying Unique Thermochromism and Magnetic Phase Transition

Cited by 58 publications

References 15 publications

A Niccolite Structural Multiferroic Metal–Organic Framework Possessing Four Different Types of Bistability in Response to Dielectric and Magnetic Modulation

A Niccolite Structural Multiferroic Metal–Organic Framework Possessing Four Different Types of Bistability in Response to Dielectric and Magnetic Modulation

Dynamic molecular crystals with switchable physical properties

Bistability in Organic Magnetic Materials: A Comparative Study of the Key Differences between Hysteretic and Non‐hysteretic Spin Transitions in Dithiazolyl Radicals

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