Unexpected acridine-fused aza-BODIPY photosensitizer originated from pyrrole with a –CH2–CH2− chain

Utilizing the rigid pyrrole with the−CH 2 –CH 2 − chain, an unexpectedly asymmetric aza-BODIPY NOMe with fully conjugated structure (−CH CH−) has been synthesized, beyond the empirical scope of Carreira's method. The intersystem crossing (ISC) is enhanced due to heteroatom effect of acridine making NOMe efficient heavy-atom-free photosensitizer of singlet oxygen (Φ Δ = 0.27) and type-I ROS . Importantly, the dye can be efficiently excited in the far-red region of the electromagnetic spectrum (λ abs = 716 nm, ε = 165000 M −1 cm −1 ). Nanoparticles prepared from NOMe show a significant inhibitory effect on animal tumor tissues when subjected to 690 nm laser irradiation, including the suppression of cell proliferation , the promotion of apoptosis, and the interference with the normal structural integrity of the tumor tissue. • Asymmetric aza-BODIPY NOMe with fully conjugated structure (−CH CH−) was synthesized. • The intersystem crossing (ISC) is enhanced due to the heteroatom effect of acridine . • Nanoparticles prepared from NOMe show a significant inhibitory effect on animal tumor tissues.