Synthesis, photophysical studies of positional isomers of heteroaryl BODIPYs, and biological evaluation of Di-pyrrolyl BODIPY on human pancreatic cancer cells

Abstract Mono/di-heteroaryl-bora-diazaindacene (1–6) were synthesized and their photophysical, electrochemical properties and cytotoxicity of 6 against pancreatic cancer (PANC-1) cells were studied. A comparison of some of the properties with their positional isomers (1 iso – 6 iso ) is also presented here. The hetero-aryl groups on −3 or −3,5 and −2 or −2,6 positions of BODIPY altered the photophysical properties considerably as compared to unsubstututed BODIPY. In general, β-substitution (-2 & 6-positions) produced slightly more bathochromic shift as compare to α-substitution (-3 & 5-positions). BODIPY derivatives having two pyrrole groups showed absorption and emission in therapeutic window (∼650–800 nm). Most bathochromic absorption (at 663 nm) and emission peak (693 nm) were found for 6 and 5 , respectively. Quantum yields of these compounds were found to be as high as 0.65. Cellular uptake of compound 6 was demonstrated using PANC-1 cells. Compound 6 inhibited the viability of PANC-1 cells in a concentration-dependent manner with an IC 50 of 2.4 μ M.