Authors
Ricardo Molenda, Ha Minh Tuan, Peter Ehlers, Peter Langer
Published in
Chemistry (Weinheim an der Bergstrasse, Germany). Pages e71799. Oct 13, 2026. Epub Oct 13, 2026.
Abstract
Replacement of benzenoid subunits by isoelectronic heteroaromatic motifs, N-doping, and π-extension provide complementary strategies for modulating the electronic structure and physical properties of polycyclic aromatic π-systems. Ullazine (indolizino[6,5,4,3-aij]quinoline) can be regarded as a π-isoelectronic heteroaromatic analogue of pyrene in which one six-membered benzenoid ring is replaced by a five-membered pyrrolic ring. Ullazine derivatives are of considerable interest in materials chemistry because this structural modification substantially alters their electronic properties relative to pyrene. Herein, we report peroullazine (PU), a longitudinally π-extended ullazine analogue of peropyrene, together with the pyridinic azaperoullazines 7-APU and 8-APU. Their synthesis combines Pd-catalyzed cross-coupling with two- and fourfold alkyne benzannulation. Replacing a pyrene substructure with an ullazine unit renders these π-systems markedly more electron-rich than the corresponding peropyrene and azaperopyrene counterparts, as reflected in substantially lower oxidation potentials. Most strikingly, this pyrene-to-ullazine replacement produces strongly red-shifted optical transitions and optical gaps approaching those of considerably more π-extended teropyrenes, despite the peropyrene-sized π-system. Pyridinic nitrogen incorporation further produces pronounced position-dependent effects, with substitution at the 7-position exerting a substantially stronger influence than substitution at the 8-position on the optical, electrochemical, and protonation responses.
PMID:
42867082
Bibliographic data and abstract were imported from PubMed on 14 Oct 2026.
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