Emerging Prospects for Unusual Aromaticity in Organic Electronic Materials: The Case for Methano[10]annulene

Abstract

Unusual aromatics outside of the 6π-electron motif offer promise for functional electronic materials, and we frame this claim in the context of 10π-electron aromatics. The evolution of our understanding of 10π-electron aromatics is discussed briefly, from azulene to the [10]

Optical and electrical properties of π-conjugated polymers built with the 10 π-electron methano[10]annulene ring system

“…UV-vis spectra for spectroelectrochemical analysis were taken on a Cary 50 UV-vis spectrophotometer. More detailed information can be found in our prior reports [8,9,16]. The synthesis of Me-MT was achieved in 94 % yield via Stille coupling between 2,7-dibromo-1,6-methano [10]annulene [17] (401 mg, 1.34 mmol) and 2-tributylstannyl-5-methylthiophene (1.298 g, 3.353 mmol) in DMF (10 ml) at 80 °C for 16 h in the presence of catalytic Pd(PPh 3 ) 4 (72 mg, 0.062 mmol) according to our previously reported methods.…”

“…Polymerizable π-conjugated monomers were synthesized via Stille couplings of 2,7-dibromo-1,6methano [10]annulene with 2-tributylstannyl thiophene (to yield MT) or 5-tributylstannyl-2,2'-bithiophene (to yield MBT) [8,9], in a manner analogous to Neidlein's preparation of alkynylated annulenes using Sonogashira couplings [10]. Their naphthalene counterparts (NT and NBT) were synthesized in a similar manner starting from 1,5-diiodonaphthalene.…”

Prospecting in Hückel‐space: From Hinokitiol to Non‐benzenoid Organic Electronics

“…Initially, our work involved comparative studies of annulene‐thiophene and annulene‐furan copolymers with benzenoid copolymer model systems containing phenyl or naphthyl repeat units in order to demonstrate the extension of electronic delocalization possible within annulene‐based conjugated polymers ( e.g . Figure , top) . Our more recent investigations examined the amorphous nature of annulene‐containing polymers as thin films relevant for semiconductor device fabrication, properties deduced by thermal and X‐ray diffraction measurements (Figure , bottom) .…”

“…Figure 12, top). [54][55][56] Our more recent investigations examined the amorphous nature of annulene-containing polymers as thin films relevant for semiconductor device fabrication, properties deduced by thermal and X-ray diffraction measurements (Figure 12, bottom). [57] It should be noted here that the latter report describes a unique example that is NOT relying on the inherent electronics or aromaticity of the annulene core; rather, the structural aspects concerning non-planarity, the methylene bridge, and the racemic nature of the annulen-2,7-diyl linkages within the monomer building block all lead to a frustration of extended crystallization that commonly accompanies typical rigid-rod conjugated polymers designed for high-performance applications.…”

Ab Initio Dot Structures Beyond the Lewis Picture

“…As such, these motifs are both a generalization of the electron pair and related to Linnett’s tetrahedrons. While the term ‘electron motif’ or ’motif’ has already been used in the literature to describe arrangements of related electrons found in the electronic structure [ 11 , 18 , 19 , 20 ], we propose an ab initio definition in this work. Although these structures are not intended to replace Lewis dot structures, direct insight into the electronic structure is obtained from this generally applicable approach.…”