Synthesis and Properties of a Highly Congested Tri(9‐anthryl)methyl Radical

Abstract

The synthesis of persistent, neutral organic radicals is challenging because of their inherent reactivities.Herein, we report the synthesis and characterization of ahighly congested mesityl-substituted tri(9-anthryl)methyl (TAntM)r adical (1). The scaffold was successfully synthesized by circumventing the steric hindrance imposed by the bulky groups surrounding the central methyl carbon atom. The radical has at hreefold propeller structure,a nd the unpaired electron is mainly localized on the central carbon atom. Owing to its congested structure, 1 is remarkably stable,w hichf acilitated handling under ambient conditions.Evaluation of the dynamic behavior of the TAntM scaffold indicated that the stability is due to the bulky anthryl units and the mesityl substituents.Because of its high persistence,w ide-range absorption, and good reversible redox properties, 1 has promising applications in organic devices.

Anthracene‐Attached Persistent Tricyclic Aromatic Hydrocarbon Radicals

“…The facile dimerizationo fAnt-DPM probablya rises from the flexibility of the diphenylmethyls keleton compared with the other radicals, resulting in the s-dimerformation at 10-position of the anthryl group. [11] Thus,t he rigidity of the tricyclicr adical scaffold plays an importantr ole in the persistence of Ant-5, Ant-6,a nd Ant-7.…”

“…Interestingly,atoluene solutiono ft he s-dimer of Ant-5 showedas light color change from pale yellow to purple at high temperature (100 8C), indicating dissociation from s-dimer to am onomeric radical. In addition, am echanical grinding also causedt he dissociation of the Ant-5 s-dimer, [7,11,14] which can be recognized by ac olor change from yellow to purple (Figure S7, SupportingI nformation). It is noteworthy that these features could not be observed for the s-dimers of Ant-DPM and Ant-7 even though the C(sp 3 )-C(sp 3 ) s-bond length of the s-dimers of Ant-DPM, Ant-5,a nd Ant-7 (1.567-1.575 )a re calculated to be close to the normal C(sp 3 )-C(sp 3 ) s-bond length.…”

Synthesis, Physical Properties, and Reactivity of Stable, π-Conjugated, Carbon-Centered Radicals

“…The stability of the triphenylmethyl radical ( 1 ) is largely dependent on the steric factor of the phenyl groups [ 34 ]. We decided to investigate the effect of larger aryl groups on the stability of the methyl radical and designed a new highly congested hydrocarbon radical, trianthrylmethyl radical ( 14 ) [ 35 ]. As shown in Figure 14 , the central carbon atom of 14 , which possesses the largest spin density, is more effectively protected by three anthryl groups than that of 1 .…”

Synthesis of Anthracene‐Based Cyclic π‐Clusters and Elucidation of their Properties Originating from Congested Aromatic Planes

“…[4] These facts motivated us to design and synthesize anthracene-congested compounds, that is, p-cluster molecules. [5] Previously, we reported the unique properties of 1,2di(9-anthryl)benzene (DAB), which is the basic moiety of pclusters. These clusters undergo excimer formation at room temperature, photoisomerization to afford a highly strained intramolecular [4+4] anthracene photodimer, [6] and mechanically facilitated cycloreversion in the solid state.…”