Strategy for Stimuli-Induced Spin Control Using a Liquescent Radical Cation

Abstract

A liquescent salt based on an N -pentylphenothiazine radical cation ( 1 •+ ·NTf 2 – ) exhibited a unique crystal–crystal phase transition from a paramagnetic orange solid to a diamagnetic green solid induced by brief, weak, and pinpoint mechanostress. Electron spin resonance and electronic spectroscopies revealed that this unprecedented solid-state spin controllability was attributable to mechanostress-triggered sequential association of the highly mobile radical species occurring under neat conditions.

Rapid Luminescent Enhancement Triggered by One‐shot Needlestick‐stimulus Using a Liquescent Gold(I) Salt

“…Analogues 1 + with different counter anions, such as BF 4 − , PF 6 − , and SbF 6 − , did not show the similar behavior to 1 + ⋅NTf 2 − due to the much higher melting points [19] . The considerably lower melting point and rapid phase transition of 1 + ⋅NTf 2 − can be attributed to the flexibility of the NTf 2 − anion [15, 20] …”

Hysteretic Control of Near‐infrared Transparency Using a Liquescent Radical Cation

“…Thed evelopment of materials with hysteresis curves (Figure 1a,r ight), which can be controlled by several properties depending on the forward and backward processes of controllable physical values,i sn ecessary for creation of invisible optical sensors, multi-channel materials used for the processing of information, and high security telecommunications.W ef ocused on materials with hysteretic changes of drastic near-IR transparencyu nder heating and cooling processes.S uch systems will provide practical processes for the transparent/opaque switching of near-IR transparencyw ith sufficiently wide working temperature ranges.O pen-shell p-electronic molecules are one of suitable candidates for the motifs of the temperature-dependent control of near-IR, because they potentially exhibit dynamic changes in near-IR absorption during association/dissociation processes. [10][11][12] In this study, the solid-liquid phase transitions of dihydrophenazine radical cations [13] bearing ionic liquid properties were utilized to achieve the temperature-dependent hysteretic control of near-IR absorption. Consequently, 1C + •NTf 2 À (NTf 2 À :b is(trifluoromethanesulfonyl)imide anion) was found to exhibit hysteretic phase transitions over aw ide-temperature range with drastic changes in the near-IR transparencyu nder neat and ambient conditions without changes in visible color (Figure 1b,c).…”

“…Such systems will provide practical processes for the transparent/opaque switching of near‐IR transparency with sufficiently wide working temperature ranges. Open‐shell π‐electronic molecules are one of suitable candidates for the motifs of the temperature‐dependent control of near‐IR, because they potentially exhibit dynamic changes in near‐IR absorption during association/dissociation processes [10–12] . In this study, the solid–liquid phase transitions of dihydrophenazine radical cations [13] bearing ionic liquid properties were utilized to achieve the temperature‐dependent hysteretic control of near‐IR absorption.…”

Redox‐Induced Modulation of Exchange Interaction in a High‐Spin Ground‐State Diradical/Triradical System

“…[5] Controlling the exchange interactions between the spins in the p-electronic systemso ft hese compounds is important for manipulatingt heir magnetic properties. [4][5][6][7][8][9][10][11] Multispin molecular systems, in whichthe intramolecular exchange interactions (large/small and positive/negative) can be modulated by external stimuli, are fascinating and promisingc omponents of molecule-based spin-related device-s. [6a] However,o nly af ew organic multispin molecular systems, the intramolecular exchange interactions of which can be controlledb yo xidation/reduction, [7] light, [8] and chemical stimuli, [9] have been reported, to date. This is because multispin centers in one molecular unit generally render the moleculeu nstable under ambient conditions.…”