Hexa‐peri‐hexabenzocoronene with Different Acceptor Units for Tuning Optoelectronic Properties

Abstract

Hexa-peri-hexabenzocoronene (HBC)-based donor-acceptor dyads were synthesized with three different acceptor units, through two pathways: 1) "pre-functionalization" of monobromo-substituted hexaphenylbenzene prior to the cyclodehydrogenation; and 2) "post-functionalization" of monobromo-substituted HBC after the cyclodehydrogenation. The HBC-acceptor dyads demonstrated varying degrees of intramolecular charge-transfer interactions, depending on the attached acceptor units, which allowed tuning of their photophysical and optoelectronic properties, including the energy gaps. The two synthetic pathways described here can be complementary and potentially be applied for the synthesis of nanographene-acceptor dyads with larger aromatic cores, including one-dimensionally extended graphene nanoribbons.

Synthesis, Photophysical Characterization, and Self‐Assembly of Hexa‐peri‐hexabenzocoronene/Benzothiadiazole Donor–Acceptor Structure

“…In particular, the introduction of π‐conjugated electron‐withdrawing groups onto the electron‐rich HBC disk has been demonstrated to be an effective strategy to tune the energy levels of the molecular orbitals and broaden the absorption spectra. This is essential for applications in organic field‐effect transistors (OFETs) and organic photovoltaics (OPVs) ,,,. Nevertheless, there have been few reports on HBC‐based donor–acceptor (D–A) systems –,…”

Nanographenes as electron-deficient cores of donor-acceptor systems

“…Allowing conjugation of donor to acceptor moieties has proven as a powerful concept to modulate the optical absorption and charge transport 17 – 22 . In such donor-acceptor (D-A) conjugates 23 – 25 , NGs have typically served as donors. Recently, a few studies have switched the electronic characteristics of NGs from electron-rich to electron-poor by multiple introduction of strongly electron-withdrawing groups, such as bisimide 26 – 29 , chloro 30 , and fluoro 31 , 32 substituents.…”

Regioselective Bromination and Functionalization of Dibenzo[hi,st]ovalene as Highly Luminescent Nanographene with Zigzag Edges

“…[2] Numerous nanographenes with armchair edge structures have been synthesized and reported, showingt unable energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital( LUMO), mainly dependento nt he shapes and sizes of their aromatic cores. [3] Edge functionalization of nanographenesh as been widely studied,i mparting them with intriguing properties, [4] such as n-types emiconductor characteristics, [5] intramolecular charge-transfer, [6] and/or liquid-crystalline nature, [7] distinct from their pristine, non-substituted counterparts.H owever,s uch functionalization predominantly relies on the modificationo fs tarting materials and/orp recursor structures involving multiple synthetic steps, while post-synthetic direct substitution of nanographenee dges has been starkly underexplored. In particular,w hile there are severalv ersatile methods, such as direct borylation [8] or perchlorination of the nanographene edges, [9] selectivee dge-halogenation has rarely been reported, [10] despite the fact that halogeng roups can be converted into various other functional groups through transition-metal-catalyzed couplingr eactions.…”