Intersected Bicyclic N-Confused Corrole Dimers with Tunable Aromaticity and Topological Chirality

Despite the successful syntheses of unique porphyrinoids by oxidative cyclization of oligopyrranes, the development of bicyclic variants with unprecedented topologies, aromaticity, and chirality remains challenging. Herein, we report the syntheses of a class of bicyclic porphyrinoids based on the oxidative cyclization of heptapyrrane P₇. Thus, a nonsymmetrical intersected bicyclic N-confused corrole dimer 1 was synthesized, wherein two terminal pyrrolic α-C atoms are linked to the β-C atoms of the middle pyrrole ring. Subsequent reduction of dimer 1 afforded dimer 2 by the attachment of two hydrogen atoms. Interestingly, 1 and 2 exhibit 18π aromatic-16π antiaromatic and 18π aromatic-18π aromatic structures, respectively, and the aromaticity of 2 can be effectively modulated by solvent polarity with contribution of the zwitterionic resonance effect. Furthermore, both 1 and 2 can chelate copper ions to form 18π aromatic-nonaromatic mono-Cu(III) complex 1-Cu and nonaromatic-nonaromatic bis-Cu complex 1-Cu₂, with the absorption band edge extended to ca. 1800 nm. In addition, the distinctive structures of these compounds enable their separation into a pair of enantiomers, with (M,M)-2 and (P,P)-2 achieving the largest dissymmetry factor |g_abs| of 0.015. These results indicate that oxidative cyclization of long-chain oligopyrranes holds promise for the syntheses of novel bicyclic porphyrinoids with unprecedented topologies, tunable aromaticity, and photophysical properties as well as persistent chirality.