Synthesis and photophysical studies of heteroaryl substituted-BODIPy derivatives for biological applications

Mono and di-heteroaryl-4,4′-difluoro-8-(aryl)-4-bora-3a,4a-diaza-s-indacene (BODIPy) (1–5) were synthesized using Suzuki–Miyaura couplings. Hetero aryl substitution on 3- or 3,5-positions caused large bathochromic shifts (up to ∼150 nm) in absorption (569–652 nm) and fluorescence maxima (586–679 nm) in comparison to classical BODIPy. Quantum yields were found to be as high as 0.65. Singlet oxygen production activities of these compounds were studied by monitoring the absorbance quenching of 1,3-diphenylisobenzofuran, on exposure to light (>600 nm). Cellular uptake of compound 4 was demonstrated using cervical cancer cells and fibroblast cell line and was confirmed by the images obtained using confocal microscope.