Twisted 1‐ and 2‐Azaperopyrenes: Synthesis, Structure, and Properties

A synthesis of hitherto unknown 1- and 2-azaperopyrenes, twisted nitrogen-doped peropyrenes, is reported. The synthesis is based on a Brønsted acid-mediated benzannulation of alkynes. Key alkyne intermediates are synthesized via two complementary routes, including a Pd/C-catalyzed, copper- and amine-free Sonogashira-type coupling of (hetero)aryl chlorides, enabling access to both carbo- and heteroatom-substituted peropyrene frameworks. X-ray crystallography reveals twisted conformations with bay and end-to-end twist angles ranging between 10.0-19.9° and 5.5-25.0°, respectively, as well as unprecedented conformational isomorphism. The influence of regioselective single N-doping within the twisted peropyrene framework on the photophysical and electrochemical properties were elucidated by combined experimental and computational studies and compared with those of the carbon congener.