K‐Region‐Extended [c]‐Heteroannulated Pyrenes

Abstract

Extended fused aromatic compounds are promising materials for organic electronics. Among them, structures with five-membered annulated rings differ from those consisting only of six-membered carbocyclic rings. To date, fusion of five-membered rings has been realized mainly via the [b]-edge, and systems fused via the [c]-edge are of low stability. Whereas linearly double [b]-fused systems are stable, analogous [c]-fused systems have not been described to date. Comparable to the stabilization of longer acenes by peri-fusion, herein the synthesis of doubly [c]-annulated systems stabilized by double peri-fusion is described. The compounds were analyzed by X-ray crystallography, photophysical methods, and DFT calculations to gain deeper insight into the nature of conjugation in these new systems.

Pyridazine‐Containing Diazatwistanthracene and Tetraazatwisttetracene: Synthesis, Crystal Structures and Third Order Non‐linear Optical Properties

“…The preparation of compounds DPPA and TPPA is shown in Scheme . Compound 2 and 4 were prepared with an optimized method ,. Actually, compounds 1 and 3 are unstable, which are easy to be decomposed and oxidized to be compounds 2 and 4 under heating with the yields of 59% and 39%, respectively.…”

Pyrene-Based Diarynes as Precursors for Twisted Fused Polycyclic Aromatic Hydrocarbons: A Comparison of Two Routes

“…Besides characterization by 1 H and 13 C NMR spectroscopy, a molecular ion peak at m/z ¼ 1022.575 (calcd. for C 80 H 62 : 1022.485) for [8] þ was clearly detected by MALDI-TOF MS (see SI). As mentioned above, TMS triflate 6 was also used as an aryne precursor, which was generated by CsF in THF at 80°C…”

“…The latter was frequently used for the synthesis of PAHs, for example, dibenzo[e,l]pyrenes (path A in Scheme 1), 7 despite the fact that pyrene biscyclopentadienones are not very stable under ambient conditions and therefore difficult to purify and handle. 3,5,8 To the best of our knowledge, the approach with inverse electronic demand on the pyrene scaffold in the reaction with cyclopentadienones (path B in Scheme 1) has not been reported till date. There are a few examples where the in situ generation of pyrene-based bis-arynes has been described in the cycloaddition to furans, 9,10 benzofurans, 11 or arylacetonitrils.…”

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…Benzoylpyrenes 164.1 and 164.5 , obtained via an oxidative ring opening of cyclopentadienone units, were used by Mastalerz et al for the synthesis of hetero-[ c ]-annulated pyrenes ( Scheme 164 ; for related systems, see Schemes 170 , 173 , and 177 , in subsequent subsections). 329 Pyrrole rings, in particular, were obtained in a two-step approach consisting of condensation with hydrazine hydrate followed by reductive ring contraction with zinc dust, yielding 164.3 and 164.4 . These two compounds exhibit blue emission with quantum yields of 37 and 40%, respectively.…”