matching with the 1H NMR spectra of the authentic sample.
Further, the results indicated that the photolytic rate constant of
the polymers (3a–b) decreases as the irradiation wavelength
increases (incident intensity (I0) ¼ 1.25 1017 and 9.661 1016
photons per s cm for 310 nm and 350 nm, respectively).
Coumarin-2,4-D polymers on excitation proceed through
a singlet excited state, followed by either direct heterolytic C–O
bond cleavage or homolytic cleavage of the C–O bond, followed
by electron transfer to produce the ion pair as shown in Scheme
2. Finally, in aqueous solvent the resulting ion pair escapes
from the solvent cage and produces the corresponding photoproducts (2,4-D and hydroxylmethylcoumarin 5a–b).