Azoniadibenzo[a,j]phenalenide: A Polycyclic Zwitterion with Singlet Biradical Character

Abstract

Ap olycyclic zwitterion, azoniadibenzo-[a,j]phenalenide,h aving as inglet biradical character,w as synthesized and isolated for the first time.The negative charge was found to be delocalized over the periphery of the main core of the zwitterion and the positive charge was localized near the nitrogen atom. Its singlet biradical character was confirmed by asmall HOMO-LUMO energy gap with their spatial overlap, and observation of thermally excited triplet species together with DFT calculations.

Fully zwitterionic diaminobenzoquinonediimines promoted by cyanoaromatic N-substituents

“…However, expending the diversity of conjugated π-zwitterions is not trivial and only few strategies are emerging in the literature, notably by linking strongly electrondonating and electron-withdrawing groups (EWG) in twisted π-systems [3,12] or in polycyclic heteroaromatic compounds such as quinacridine derivatives [13,14], naphthalenediimides [15] and azoniadibenzo[a,j]phenalenides [16], which often yields photophysical properties in red to near-infrared ranges. Another remarkable strategy towards π-zwitterions is based on the design of rigid polycyclic antiaromatic species that are prompt to form stable ground-state zwitterions (Figure 1), such as tetraphenylhexaazaanthracenes (TPHA) [17][18][19][20], tetraazapentacenes (TAP) [21][22][23] and triazino-phenazine hybrid derivatives [24], bisdithiazoles [25,26] or benzoquinone dithiazoles (BDT) [27,28].…”

Toward an Air-Stable Triradical with Strong Spin Coupling: Synthesis of Substituted Truxene-5,10,15-triyl

“…Strong ferromagnetic or antiferromagnetic electron-coupling effects are widely manifested and studied with heavy atom-containing materials, which have presented promising potential for a range of unique applications, such as superconductors, − single-molecule magnets, − and spin liquids, − pertinent to topological quantum computation . Nonetheless, such properties are far less explored with organic molecules because either weak spin coupling or low chemostability is typically observed with open-shell organic molecules. − However, as widely demonstrated in the opto-electronic and semiconducting applications, besides the superior mechanical assets, organic materials prevailingly surpass inorganic counterparts in terms of their economic and environmental costs. Moreover, versatile methods are readily available for modifying the structures and fine-tuning the properties of various organic molecules, which further boost their application values. − Thus, with the desire to induce and harness spin-related properties from organic molecules, the first order of issue arises to design and prepare air-stable organic polyradicals boasting a strong spin coupling effect.…”

Isolation and characterisation of a stable 2-azaphenalenyl azomethine ylide

“…1). Dibenzo derivatives of 6 [10][11][12][13][14][15] were explored earlier by Beljonne, Feng and Müllen, who also reported their absorption spectral properties 10 . N-Substituted 2azaphenalenyl derivatives 5 can be structurally visualized in three resonance forms including azomethine ylide A, azaphenalenyl anion B and biradical C (Fig.…”