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.

Synthesis and Isolation of a Kinetically Stabilized Crystalline Triangulene

“…However, the electronic structure of 1c is quite different from that of 1a because of the strong perturbation by oxygen atoms. , In this context, herein we describe the synthesis and isolation of kinetically stabilized triangulene derivative 1d in a crystalline form. The key to success is the introduction of three mesityl groups onto the γ-carbons, − and we also provide its fundamental properties, including the X-ray crystal structure as the first crystallographic structural elucidation of hydrocarbons with a triplet ground state …”

Bis-periazulene (Cyclohepta[def]fluorene) as a Nonalternant Isomer of Pyrene: Synthesis and Characterization of Its Triaryl Derivatives

“…For the deprotonation of 2 + into 1 , the choice of a suitable base was important. When we applied sodium hydride to the deprotonation of 2d + , , an over-reduced radical anion 1d •– , confirmed by X-ray analysis, was unexpectedly obtained (Figure S10). Alternatively, changing the base into lithium hydride successfully transformed 2 + into the desired molecule 1 .…”

“…No solvatochromism of 1c / e was observed among THF, CH 2 Cl 2 , and benzene (Figure S32 and S37). , According to the small Δ E S–T , the absorption spectrum of 1d at room temperature should be composed of absorption bands derived from the triplet species as well as ground-state singlet species. The variable temperature measurements of 1d in THF showed the consecutive spectrum changes with isosbestic points upon cooling from 294 to 183 K (Figure S39).…”

Recent progress in open-shell organic conjugated materials and their aggregated states

“…6) with a singlet diradical ground state. 64 Further study indicates its zwitterion structure with negative charge delocalized over the periphery of the molecule and positive charge mainly localized near the nitrogen atom. Yamagushi et al reported a B containing monoradical 28 with spin density effectively delocalized through the vacant p-orbital of the boron atom.…”