Photochemistry of 3,4,9,10-perylenetetracarboxylic dianhydride dyes: visible absorption and fluorescence of the di(glycyl)imide derivative monomer and dimer in basic aqueous solutions

The synthesis of the di(glycyl)imide derivative of 3,4,9,10-perylenetetracarboxylic dianhydride and its spectral properties in basic aqueous solutions are described. The monomer and dimer forms of the dye coexist in H2O (10−3 M NaOH) with an equilibrium association constant K = 1.0 × 107 M−1 (24 °C) for dye concentrations up to 2.4 × 10−5 M (degree of dimerization equal to 96%). The 0—0 absorption band of the monomer at 532 nm is split by exciton interaction in the dimer into a higher energy band at about 500 nm and a lower energy band at about 542 nm. The fluorescence quantum yield ΦF of the monomer is about 1,0, while the dimer is non-fluorescent (ΦF < 0.02). The addition of ethanol favors dissociation of the dimer, while the addition of NaCl favors its formation. The dye in 50vol.%-ethanol−50vol.%H2O (10−3 M NaOH) has a ΦF of 0.96 ± 0.04.