Synthesis and Optical Properties of Phenylene-Containing Oligoacenes

Abstract

Synthesis of a new class of fully unsaturated ladder structures, phenylene-containing oligoacenes (POAs), using 3,4-bis(methylene)cyclobutene as a building block for sequential Diels-Alder reactions is described. The geometric effects of strain and energetic cost of antiaromaticity can be observed via the optical and electrochemical properties of the reported compounds. The resulting shape-persistant ladder structures contain neighboring chromophores that are partially electronically isolated from one another while still undergoing a reduction in the band gap of the material.

Phase Transition of [2,2]‐Paracyclophane – An End to an Apparently Endless Story

“…reported a series of compounds in which not benzene but naphthalene or anthracene units are separated by four‐membered rings (see for example compound 5 in Figure 1). 6 Very few phenylenes containing nitrogen ( 1 – 4 ) are known. Some were prepared early, such as 1 by Blatchly,2 2 by Cava,3 and 3 by Hünig 4.…”

How Boron Doping Shapes the Optoelectronic Properties of Canonical and Phenylene‐Containing Oligoacenes: A Combined Experimental and Theoretical Investigation

“…The resulting compound DBI (Figure ) relates to the linear [ N ]phenylenes, which are composed of alternating arrays of linearly fused benzene and cyclobutadiene moieties. In these compounds, the π electrons tend to form localized Clar's sextets within the six‐membered rings, thereby minimizing the antiaromatic character of the cyclobutadiene linkers . In contrast to DBI , DBP constitutes a derivative of the acenes, which typically contain the fewest number of Clar's sextets per number of aromatic rings.…”

“…In the quest for stable, high‐performance optoelectronic materials, Swager et al. have prepared a series of phenylene‐containing oligoacenes (POAs) . Some remarkable nitrogen‐doped variants have recently been published by Bunz et al .…”

A Stable Bis(benzocyclobutadiene)‐Annelated Tetraazapentacene Derivative

“…Before 2008, this field was ab ackwater of organic chemistry apparently without promise or excitement, yet another set of laboratory curiosities. [7] Extending the (aza)acene backbonev ia benzocyclobutadiene annelation leads to stable (aza)phenylenes ( Figure 1). [4] We werei nterested to increase the size of the p-system of azaacene-like species, without compromising their stability.I n principle, this is possible by insertion of pyrene units, generating multiple Clar sextets.A lternatively,i ti sp ossible to interject antiaromaticc yclobutadiene units into the aromatic acene-ladder, as shownf irst by Vollhardt for the hydrocarbon-based phenylenes.…”

“…[6] While in Vollhardt's phenylenes,t here is as trict sequence of benzenea nd cyclobutadiene units,S wager extended the concept to larger acenes and successfully interspersed cyclobutadienee lements between anthracene units and demonstrated that thesem aterials are attractive emitters. [7][8][9][10] [a] Dr.P . [8] We have already synthesized as eries of unsymmetrical biphenylene-substituted azaacenes, but the synthesis of symmetrical azaacenes is more challenginga nd desirable for their potential applicationi no rganic electronics.…”