Regioselective late-stage functionalization of tetraphenylenes: rapid construction of double helical architectures and potential hole transport materials

Abstract

Herein we report a novel approach for diversification of tetraphenylene via regioselective late-stage iodination followed by atom(s) insertion into the resulting cyclic iodonium salts. Thus, the steric hindrance effect of tert-butyl facilitates the regioselective synthesis of two cyclic iodonium salts of 2,7,10,15-tetra-tert-butyltetraphenylene. In addition, two more cyclic iodonium salts of 2,7,10,15-tetranitrotetraphenylene were also readily synthesized due to the meta-position induced effect of the electron-withdrawing NO₂ group. Subsequent functionalization of these tetraphenylene-based cyclic iodonium salts via diverse atom(s) insertion processes led to several tetraphenylene-based [8 + n] and [n + 8 + n] fused rings including fascinating double helical architectures. This newly developed late-stage functionalization methodology was also successfully applied to rapid synthesis of potential hole transport materials, thereby demonstrating its robust synthetic value in both tetraphenylene chemistry and materials science.