Transformation of a benzocorrole isomer into pyrrole-containing polycyclic molecules via copper-mediated cleavage and annulation†

Abstract

We present the oxidative transformation of a corrole isomer, namely, dibenzocorrorin (3), featuring a modified connectivity pattern of bipyrrole moieties within the corrole scaffold, resulting in the formation of pyrrole-embedded polycyclic molecules (1 and 2). The X-ray crystallography analysis of compound 1 revealed the establishment of three C–N bonds through nitrogen sites in the pyrrole and indole rings, leading to a highly π-conjugated core with nine fused aromatic rings. Notably, the β-pyrrole protons of the diazadicyclopentaazulene moiety displayed significant high-field shifts in the ¹H-NMR spectrum, attributed to the 12π antiaromatic contribution of the diazadicyclopentaazulene segment, as indicated by NICS and ACID plot analyses. Compound 1 exhibited a broad near-infrared absorption beyond 1000 nm, a narrow electrochemical energy gap (ΔE = 1.15 V), a short excited-state lifetime, and stable photothermal conversion capability. The crystalline packing structure of 1, characterized by staircase-like stacking along the long axis of needle-shaped crystals, facilitated the fabrication of a single-crystal organic field-effect transistor. The resulting device demonstrated p-type semiconductor behaviour, emphasizing the potential of 1 in near-infrared optoelectronic applications.