An Electron‐Deficient Azacoronene Obtained by Radial π Extension

Abstract

A hexapyrrolohexaazacoronene derivative containing 37 fused rings, the largest such system to date, was obtained from a naphthalenomonoimide–pyrrole hybrid in a concise and efficient synthesis. This large heterocycle is electron‐deficient and shows extended redox activity, spanning at least 13 oxidation levels, but is otherwise chemically stable. Radial expansion of the π system creates a chromophore characterized by strong fluorescence and solvatochromism in the neutral state, and strong near‐infrared absorption in the charged states. Additionally, the enlarged and ruffled aromatic surface supports a unique self‐assembly mode in the crystal, leading to the formation of highly solvated organic clathrates.

Electron‐Deficient Bipyrrole Boomerangs: Bright Fluorophores Obtained via Double C−H Bond Activation

“…In the course of our ongoing research on extensively fused oligopyrroles, we decided to explore double C−H bond activation as a potentially efficient strategy for linking heterocyclic moieties, including electron‐deficient ones, into large π‐conjugated structures. We focused on the synthesis of π‐extended bipyrrole boomerangs, which we envisaged as a new class of tunable donor–acceptor (D‐A) chromophores (Scheme ).…”

New advances in chiral nanographene chemistry

“…77 Stępień and coworkers previously reported a successful synthesis of a hexapyrrolohexaazacoronene (HPHAC) derivative through FeCl 3 oxidative cyclization of a hexapyrrolylbenzene precursor, producing a nonplanar but achiral final structure. 78 However, the same group later discovered a more stereo-controlled method of preparing a similar structure by utilizing more sterically hindered bay positions. It was noted that this new steric strain could be synthetically overcome by utilizing bromine electrophiles rather than more high-potential oxidants.…”

Acenaphtho[1,2‐d][1,2,3]triazole and Its Kuratowski Complex: A π‐Extended Tecton for Supramolecular and Coordinative Self‐Assembly

“…π-Extension of pyrroles, for instance, has been intensely explored as a general strategy toward lowbandgap porphyrinoids and other oligopyrrolic molecules. [1,2] In this context, fusion of acenaphthylene to the β-β edge of pyrrole (1-2, Figure 1) provided particularly striking examples of π-extended chromophores, [3,4] and has been more recently elaborated into a general strategy toward oligopyrrole-naphthalenemonoimide hybrids, [4][5][6][7][8][9][10] characterized by extended NIR absorptions and multilevel redox chemistry. Acenaphthylenefused imidazoles (3) have found use as precursors of Nheterocyclic ligands with applications in Pd-, Ni-, and Cucatalyzed coupling reactions.…”