“…It has been explained by the effect of large stabilization upon excitation along with the bending of the fused BODIPY core, and the accessible S1/S0 conical intersection point [16]; the small geometrical evolution prompts the nonradiative relaxation to the ground state [43]. We also cannot exclude fluorescence quenching by internal charge transfer (ICT) in derivatives 9 and 10 [42,44,45]. Different amounts of DMSO were added to PBS to dissolve the BODIPY derivatives because, except for 10 (the p-phenyl polyethylene glycol substituents were introduced in 10 to improve its solubility in aqueous solutions), they are only par- max and λ em max of 6, bearing an electron-withdrawing group at position 2, are slightly hypsochromically shifted.…”