Starphenes and Phenes: Structures and Properties

Abstract

Acenes have been known for a long time but their larger congeners, starphenes and phenes, have only been recently accessible as processable and characterizable derivatives. In this personalized review, we delineate the synthetic approach developed by our group over the last four years. Nickel-mediated Yamamoto coupling of ortho-dibromoacenes generates cyclotrimers. If performed in a shotgun approach, i.e. with substituted 2,3-dibromotetracene or -pentacene in the presence of ortho-dibromobenzene or ortho-dibromoveratrole, trimeric phenes and tetramers would result. Cyclotrimers formed by a pentacenylene and two phenylenes are formally dibenzo[a,c]hexacenes. A direct way to obtain these species is to employ Stille coupling of a dimethylstannafluorene with 2,3-dibromoacenes. If tetrabromoanthracenes or tetrabromopentacenes are fed into this process, tetrabenzopentacene and tetrabenzoheptacenes are easily accessible. Optical and quantum-chemical characterizations provide insight into the electronic situation and aromaticity of these species.

Two Dimensional Triptycene End‐Capping and Its Influence on the Self‐Assembly of Quinoxalinophenanthrophenazines†

“…Acenes or related compounds that contain triphenylenes at their peripheral ends are known to stabilize the π‐backbones electronically. [ 32‐36 ] The structural motif of triphenylenes allow the implementation of three or four triptycene end‐caps to longer QPP derived poly N ‐heterocyclic aromatic compounds, which is introduced herein. [ 37‐38 ]…”

The Magnetic Response of Starphenes

“…Starphenes are a series of star-shaped polycyclic aromatic hydrocarbons (PAH) consisting of three identical linear acenes interconnected by a six-membered ring (6-MR) belonging to the D 3h symmetry [1,2]. As with most large PAHs, scientific interest in two-dimensional organic structures increases due to their potential applications as molecular electronic devices [3].…”

A Large Starphene Comprising Pentacene Branches

“…Starphenes are 2D polyaromatic hydrocarbons (PAHs) comprising three acene [1] arms connected through a single benzene ring [2] . These structures can be used in single‐molecule electronics as NAND [3] or NOR [4] gates.…”

“…The most applied synthetic strategy towards these soluble starphenes is a palladium‐catalysed [2+2+2] cycloaddition reaction of in situ generated arynes from appropriate arene derivatives [11–13] . Another often used approach is a nickel‐mediated Yamamoto coupling reaction of ortho ‐dibrominated arenes [2, 6, 10, 14] …”