5,14-Diaryldiindeno[2,1-f:1′,2′-j]picene: A New Stable [7]Helicene with a Partial Biradical Character

Abstract

1′,2′-j]picene (DDP, 1), a thermally and chemically stable helical arene, can be prepared from 1,4-bis[2-(arylethynyl)phenyl]benzene in four synthetic steps. Its helical backbone, which incorporates an oquinodimethane moiety, was verified by X-ray crystallography, and this structural feature results in a very high barrier to racemization (exceeding 50 kcal/mol). DDP possesses versatile and promising properties, including a small HOMO−LUMO energy gap (1.31 eV for the dimesitylsubstituted derivative 1ab), an electron spin resonance (ESR)active character, a small triplet−singlet energy gap (4.75 kcal/mol), broad photoabsorption covering the ultraviolet, visible, and near-infrared (NIR) regions, two-photon absorption in the NIR range, and respectable ambipolar charge-transport behavior in a solution-processed organic field-effect transistor.

Improving Performance of Perovskite Solar Cells Using [7]Helicenes with Stable Partial Biradical Characters as the Hole‐Extraction Layers

“…We have recently developed a series of novel helicenes and unveiled their versatile properties . Among which, the most interesting feature is that they have stable open‐shell singlet biradical ground states, and one of π bonds in a molecule is pushed to the dissociation limit to result in two weakly coupled unpaired electrons.…”

“…As mentioned earlier, we are interested in exploring their functionality as the HEL/HTL in PVSCs owing to their appealing properties. To this end, 1ab and 1bb were herein chosen as the studied helicenes based on their decent semiconducting property …”

“…Herein, we are interested in investigating the effectiveness of a series of [7]helicenes to serve as the hole‐extraction/transporting layer (HEL/HTL) in the p–i–n PVSCs based on our recent interesting finding of their inherent singlet biradical characters at room temperature . Note that helicene is a class of material consisting of screw‐skeleton shaped polycyclic aromatics and helically fused aromatic rings, varying from monolayer to multilayer structures .…”

“…Recently, we synthesized two novel and stable [7]helicenes (denoted as 1ab and 1bb), which possess open‐shell singlet biradical ground states at room temperature . Besides this unique feature, we found the following properties that are appealing for serving as a HEL/HTL in the p–i–n PVSCs.…”

Stable Diindeno‐Fused Corannulene Regioisomers with Open‐Shell Singlet Ground States and Large Diradical Characters

“…The delocalization of radicals over three-dimensional (3D) surfaces is expected to generate unique properties but is much less explored than their planar analogues. Recently, curved diindeno-fused bischrysene (XII) [15] and picene (XIII) [16] were developed by the groups of Feng and Wu, respectively, and these demonstrated high stability under ambient conditions. Corannulene, a bowl-shaped non-alternant PH with 20 pelectrons, consists of one five-membered ring and five sixmembered rings.…”