Dissecting Substituent Effects on Electronic Structure and Chiroptical Response in Phenazine‐[7]Helicene

ABSTRACT

Helicenes are intrinsically chiral π‐conjugated molecules whose rigid, non‐planar helical architectures make them attractive candidates for chiroptical and optoelectronic applications. However, achieving pronounced modulation of their photophysical and chiroptical properties through minimal structural modification remains a key challenge. Here, we address this challenge by demonstrating that subtle peripheral functionalization of phenazine‐fused [7]helicene derivatives enables substantial and systematic tuning of optical and chiroptical behavior without perturbing the helicene framework. The introduction of electronically diverse substituents induces marked variations in absorption and emission characteristics, photoluminescence quantum yields, HOMO–LUMO energy gaps, excited‐state dynamics, circular dichroism, and circularly polarized luminescence. Notably, B _CPL is modulated from 2.65 to 112.48 M ⁻¹ cm ⁻¹ , corresponding to an approximately 42‐fold enhancement, accompanied by a 7‐fold increase in g _lum achieved solely through helicene functionalization. These findings establish minor structural modification as an efficient strategy for fine electronic and chiroptical control, providing valuable design principles for helicene‐based chiral photonic and optoelectronic materials.