Theoretical Study of the Stable Radicals Galvinoxyl, Azagalvinoxyl and Wurster’s Blue Perchlorate in the Solid State

Abstract

Calculations on crystalline organic radicals were performed to establish the ground states of these materials. These calculations show that the radicals may interact, depending on their orientation in the crystal structure. For galvinxoyl, a second structure is proposed which is similar to that of azagalvinoxyl, in which the radicals form pairs. This structure accounts for the anomalous magnetic properties of galvinoxyl at low temperatures.

Photophysics of the galvinoxyl free radical revisited

“…6 Delocalization of the unpaired electron over the whole aromatic system has also been evidenced in liquid solution via infrared 15 and EPR spectroscopy 16 and reproduced by quantum chemical calculations. 10 The lowest energy transition observed in the electronic absorption spectrum is located at 860 nm (1.4 eV), 5 in agreement with CNDO/S quantum chemical calculations that found the lowest excited state at the same energy. 17 Galvinoxyl is a phenoxyl type radical and, apart from one publication 18 about the fluorescence of 2,4,6-tris(tert-butyl)phenoxyl radical that has been questioned later on, 19,20 no emission has been reported for this family of radicals.…”

“…Unlike closed-shell molecules, radicals are characterized by a high density of relatively low electronic excited states. In the case of the galvinoxyl radical, the calculations presented here indicate that optical excitation at 400 nm (3.1 eV) leads to the population of the D 9 or D 10 state, a situation that is uncommon in closed shell molecules, where at most the second or third electronic excited state is reached at such excitation energies. We will show that, contrary to what has been previously reported, the excited-state lifetime of galvinoxyl is extremely short, in agreement with the high density of states, and with a lowest electronic excited state located only 0.9 eV above the ground state.…”

Solvent-Free and Catalyst-Free Biginelli Reaction To Synthesize Ferrocenoyl Dihydropyrimidine and Kinetic Method To Express Radical-Scavenging Ability

“…Galvinoxyl radical was widely employed to evaluate the ability of an antioxidant to contribute the hydrogen atom to the oxygen radical. 40 Figure 2 showed the decrease of the concentration of galvinoxyl radical in the presence of compounds 5−11. Other DHPMs cannot quench the galvinoxyl radical.…”

Reversible Solution π‐Dimerization and Long Multicenter Bonding in a Stable Phenoxyl Radical

“…Winter and co‐workers have described π‐dimer formation through host–guest interactions in solutions containing a viologen diradical cation . The well‐known galvinoxyl radical (Scheme ) and aza‐analogue are also known to dimerize in the solid‐state and have interesting temperature dependent magnetic profiles . Solution EPR studies of galvinoxyl radical at different temperatures have revealed behavior consistent with dimerization; however, the nature of the diamagnetic species is unclear .…”

“…[21][22][23] The well-known galvinoxyl radical( Scheme 1) anda za-analogue are also known to dimerize in the solid-state and have interesting temperature dependentm agnetic profiles. [24] Solution EPR studies of galvinoxyl radicala tdifferent temperatures have revealed behavior consistentw ith dimerization; however,t he nature of the diamagnetic species is unclear. [25] In 2013, Mayer and co-workers reportedt he X-ray crystal structure and dissociation thermochemistry of a2 ,6-di-tert-butyl-4-methoxyphenoxyl radical dimer (the dimerization is thermally reversiblei ns olution), which revealed the occurrenceo falong and very weak CÀC sigma bond.…”