1,2,5,6,9-Pentaazacoronenes (PACs) and π-Extended PAC Derivatives: Synthesis, Crystal Structure, and Optical and Redox Properties

Abstract

A novel class of 1,2,5,6,9-pentaazacoronene (PAC, 1) derivatives and π-extended PAC derivatives, chromeno[2,3,4-ij]pentaazacoronenes (CPACs, 2), has been successfully synthesized on the basis of intramolecular diazo-coupling reaction and Pictet–Spengler cyclization. Single-crystal analysis demonstrates that 1o (R1 = H) displays a herringbone packing motif while 1s (R1 = C3F7) packs into an S-shaped arrangement. Photophysical and electrochemical studies indicated that the new PAC system manifested significantly red-shifted absorption and emission capacity, larger Stokes shifts, and narrower HOMO–LUMO energy gaps.