Magnetic Bistability in a Discrete Organic Radical

Abstract

Molecular assembly with magnetic bistability has been of considerable interest for application as electronic devices. In contrast to transition-metal complexes, magnetic bistability so far observed in organic radical crystals is mainly caused by intermolecular electron-exchange interaction. We now report that the magnetic bistability in an organic radical can also be caused by intramolecular electron-exchange interaction. The diradical salt of 1,4-di(bisphenylamino)-2,3,5,6,-tetramethylbenzene undergoes a phase transition with a thermal hysteresis loop over the temperature range from 118 to 131 K. The phases above and below the loop correspond to two different singlet states of the diradical dication. The results provide a novel organic radical material as an unprecedented instance of an intramolecular magnetic bistability revalent to the design of functional materials.

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

“…[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.…”

Redox-Induced Gating of the Exchange Interactions in a Single Organic Diradical

“…21A promising alternative to SMMs is offered by all-organic radical molecules 7 where the magnetism arises from the unpaired spins of carbon atoms. 22,23 The simplicity of their spin structure and the absence of metal centers have proven to yield robust molecular junc-Cl…”

Isomerism, Diradical Signature, and Raman Spectroscopy: Underlying Connections in Diamino Oligophenyl Dications

“…The 4,4′‐di(bis(1,4‐methoxyphenyl)amino) p ‐monophenyl ( 2 +2 ) and p‐ monophenyltetramethyl ( 2(CH 3 ) 4 +2 ) dications in Figure have been reported to display nearly closed‐shell ( y ≈0) and large diradical ( y ≈1) characters, respectively. Indeed, at the same level of calculation than for 1 +2 , the y theoretical values for 2 +2 ( y =0.16) and for 2(CH 3 ) 4 +2 ( y =0.90) have been calculated which are in accordance with the reported data ,.…”

“…The 4,4′‐di(bis(1,4‐methoxyphenyl)amino) p ‐monophenyl ( 2 +2 ) and p‐ monophenyltetramethyl ( 2(CH 3 ) 4 +2 ) dications in Figure have been reported to display nearly closed‐shell ( y ≈0) and large diradical ( y ≈1) characters, respectively. Indeed, at the same level of calculation than for 1 +2 , the y theoretical values for 2 +2 ( y =0.16) and for 2(CH 3 ) 4 +2 ( y =0.90) have been calculated which are in accordance with the reported data ,. In the case of 2(CH 3 ) 4 +2 , the strong steric repulsion of the innermost methyls with the peripheral benzenes provokes the distortion of the central phenyl group around the axis connecting the two CN bonds, an effect that occurs at the expenses of the rupture of one of the formally C=N bonds producing the formation of a diradical that liberates steric crowding (i. e., the formation of the diradical form of 2(CH 3 ) 4 +2 is also fueled by the aromaticity gaining in the central benzene).…”