To evaluate the efficiency of 1 O2 generation, we measured its luminescence spectrum around 1270 nm. Figure ,D shows the luminescence intensity relative to the absorbance at the excitation wavelength (500 nm). As expected, relative luminescence intensity is approximately 200-times higher for BODIPY-NOD-3 than for BODIPY-NOD-2 which does not contain heavy atoms. Surprisingly, its boron-alkylated analogue BODIPY-NOD-5 exhibits ~100-times lower relative luminescence compared to BODIPY-NOD-3. We conclude that exchange of fluorine atoms for methyl groups result in significant reduction of 1 O2 generation efficiency.