Benzenetriimide‐Based Molecular Conductor with Antiferro‐ to Ferromagnetic Switching Induced by Structural Change of π‐stacked Array

Abstract

Benzenetriimide (BTI) is a promising building block for materials chemistry due to its characteristic 3-fold symmetry and redox properties, whereas little is known about its conductive and magnetic properties. In this study, we synthesized three chargetransfer complexes based on N,N',N''-trimethylbenzenetriimide (BTI-Me). One of the complexes contains isolated dimers of BTI-Me radical anion (BTI-Me *À ), while the other two have the infinite π-stacked array of BTI-Me with the formal charge of À 0.5. The latter two complexes did not show metallic behavior but showed semiconducting behavior probably due to the characteristic insulation in one-dimensional electron system, socalled charge ordering and dimer-Mott insulation. The magnetic susceptibility of the complex in dimer-Mott state exhibits an unusual transition from antiferromagnetic to ferromagnetic spin states with the hysteresis loop of 15 K derived from the structural phase transition around 130 K. These properties were also supported by DFT calculations.

Chiral Benzene Triimide (BTI) Radical Anions for Probing the Interplay of Unpaired Electron Spin and Chirality

“…[32][33][34] BTIs can be transformed into radical anions by chemical reduction, representing a new type of stable radicals showing unique magnetic property and conductivity. [35][36][37] The peculiar stability of BTI-radicals (bulky protecting groups are not necessary) was accounted for by the delocalization of spin over the aromatic backbone and the absence of reactive carbon center. Our previous study indicated that BTI radicals show distinct NIR absorption which was ascribed to the transition between singly occupied molecular orbital (SOMO) of the unpaired electron spin and LUMO + 1 orbital.…”

“…Our previous study indicated that BTI radicals show distinct NIR absorption which was ascribed to the transition between singly occupied molecular orbital (SOMO) of the unpaired electron spin and LUMO + 1 orbital. [36,37] We envisioned BTI could be a good molecular platform to construct stable chiral radicals. As chiral groups bearing various α-substituents could be readily introduced on the three nitrogen atoms, [32] different interplay of the unpaired electron spin and chirality is anticipated to be modulated (Scheme 1).…”

“…Benzene triimide (BTI) is an intriguing building block possessing C 3 ‐symmetry, electron‐deficiency, functionalization and anion binding ability [32–34] . BTIs can be transformed into radical anions by chemical reduction, representing a new type of stable radicals showing unique magnetic property and conductivity [35–37] . The peculiar stability of BTI‐radicals (bulky protecting groups are not necessary) was accounted for by the delocalization of spin over the aromatic backbone and the absence of reactive carbon center.…”

“…The peculiar stability of BTI‐radicals (bulky protecting groups are not necessary) was accounted for by the delocalization of spin over the aromatic backbone and the absence of reactive carbon center. Our previous study indicated that BTI radicals show distinct NIR absorption which was ascribed to the transition between singly occupied molecular orbital (SOMO) of the unpaired electron spin and LUMO+1 orbital [36,37] . We envisioned BTI could be a good molecular platform to construct stable chiral radicals.…”