Fig. 2: Transient absorption spectra (TAS) of p-coumaric acid in different environments.
From: Radiationless mechanism of UV deactivation by cuticle phenolics in plants
a TAS of a methanol solution of p-coumaric acid (10−3 M), powder p-coumaric acid and a polyalkylcoumarate oligomer. Top, heat maps displaying changes in optical density (m∆OD) with time and wavelength after a pump pulse of 300 nm. Bottom, TAS graphs display the evolution of differences in absorbance with wavelength at given delay times. b NMR spectra after 5 h of continuous irradiation at 300 nm of p-coumaric acid solution and solid samples. Red peaks in the solution sample are characteristic of the cis-isomer whereas those in black are of trans-isomer. To the right, a schematic representation of the processes occurring during sample irradiation. In black trans p-coumaric acid, in red cis p-coumaric acid.
