Fig. 1b shows the 1H-NMR spectra. In the spectrum at time
zero, the chemical shifts between 1 and 4.5 ppm, which are
characteristic of aliphatic protons, can be observed.
The disappearance of the signal at a chemical shift of 5.4 ppm
(attributable to the phenol group present in the three dyes) and
the weak, broad signals at chemical shifts around 7.5 ppm