Controlled Helical Distortion of Double Thia[7]helicenes via Inner-Rim Alkyl Substitution

Precise control of helical distortion in double helicenes is challenging due to their high intrinsic strain. Herein, we report modulation of helical distortion in a double thia[7]helicene through inner-rim alkyl substitution. Structural and computational studies reveal increased backbone distortion and enhanced intramolecular through-space interactions. These subtle structural variations lead to notable changes in optical, electronic, and chiroptical properties and enable efficient singlet oxygen photosensitization.