Tetraazacoronenes and Their Dimers, Trimers and Tetramers

Abstract

Tetraazacoronenes were synthesized from bay‐functionalized tetraazaperylenes by Zr‐mediated cyclization and four‐fold Suzuki–Miyaura cross coupling. In the Zr‐mediated approach, an η4‐cyclobutadiene‐zirconium(IV) complex was isolated as an intermediate to cyclobutene‐annulated derivatives. Using bis(pinacolatoboryl)vinyltrimethylsilane as a C2 building block gave the tetraazacoronene target compound along with the condensed azacoronene dimer as well as higher oligomers. The series of extended azacoronenes show highly resolved UV/Vis absorption bands with increased extinction coefficients for the extended aromatic cores and fluorescence quantum yields of up to 80 % at 659 nm.

Chiral Bay-Alkynylated Tetraazaperylenes: Photophysics and Chiroptical Properties

“…In the present work, we aim to obtain conformationally stable tetraazaperylene derivatives through steric congestion in the bay -area introduced by alkynyl substituents, a structural motif that is, to the best of our knowledge, unique in perylene chemistry. Initially targeted for the synthesis of tetraazacoronenes, a series of bay -alkynylated OAPPDO derivatives has been synthesized to study the effect of the alkynyl groups on the activation barrier of enantiomerization.…”

Zipping up tetraazaperylene: synthesis of tetraazacoronenes via double coupling in the bay positions

“…Both patterns mirror the relationship between the two parent polycyclic aromatics. 23,24 Recently, we reported a first effort to p-extend the OAPPDOs by using a double Suzuki-Miyaura cross coupling reaction with (E)-1, 2-bis(pinacolatoboryl)vinyltrimethylsilane as a C 2 -synthon. However, this not only gave rise to the targeted tetraazacoronene parent compound but also to its two-, three-and fourfold condensed congeners thus lacking in selectivity with respect to the actual target.…”

“…However, this not only gave rise to the targeted tetraazacoronene parent compound but also to its two-, three-and fourfold condensed congeners thus lacking in selectivity with respect to the actual target. 23 The coupling method itself was first described by Hiyama and coworkers in 2008, 25 who employed 1,2-bis(pinacolatoboryl) alkenes as building blocks in the chemistry of functional PAHs. 26 Given this lack of selectivity observed in our first application of Hiyama's method, we decided to modify the approach so as to suppress the competing oligomerizations.…”

“…This illustrates that fusion of phenanthro moieties, which can be structurally seen as half of a coronene molecule, to OAPPDO 1 leads to a full delocalization of the p-electrons around the whole molecule, as also observed by ACID analysis of fused tetraazacoronenes. 23 The aryl substituted tetraazacoronenes 2a-2d and 2f dissolve very well in all common organic solvents, which is due to the Scheme 1 Synthesis of the tetraazacoronene 2a-2e. N-hexyl substituents and the free rotation of the aromatic moieties (see crystal structures of 2a and 2c).…”

“…This illustrates that fusion of phenanthro moieties, which can be structurally seen as half of a coronene molecule, to OAPPDO 1 leads to a full delocalization of the π-electrons around the whole molecule, as also observed by ACID analysis of fused tetraazacoronenes. 23…”