Decaphyrin Conformers Stabilized by Pseudo-Rigid Dipyrrolylbenzothiadiazole Blocks: Synthesis, Structures and Interconversion

Two conformers of a dipyrrolylbenzothiadiazole (DP-BTD) embedded decaphyrin(1.1.1.0.0.1.1.1.0.0) have been synthesized and separated, exhibiting crescent-shaped and figure-eight conformations, respectively. Incorporation of the hydrogen bonding-reinforced pseudorigid and electron-withdrawing DP-BTD segments not only stabilizes the distinct conformations, but also extends the absorption to ca. 1600 nm due to the good conjugation and ICT effect. Although both conformers are stable at room temperature, reversible interconversion occurs between them upon heating or disrupting intramolecular hydrogen bonds by protonation.