... Org. ... The fluorescence lifetime measurements revealed that protonated 7 features relatively a long lifetime for organic fluorophores ... 2. (a) UV–vis and (b) fluorescence spectra of 5d and (c) UV–vis and (d) fluorescence spectra of 7 in dichloromethane ((a) 20 μM, (b) 2 μM, (c) 20 μM ...