Speaker
Description
Pyrrole is a common aromatic motif present in many biological chromophores that can be electronically photoexcited by solar radiation. In isolated conditions, its relaxation dynamics takes place in tens of femtoseconds (fs), involving the coupling of πσ reactive states to the bright ππ states that mediate the photoexcitation.1 This behavior is thought to have important consequences in the response exhibited by biomolecules to radiation exposure.2 However, the relaxation mechanisms observed in isolated conditions are fully conditioned by the environment, in particular, by the specific interactions established by the surrounding molecules.3 In this work, we have tracked the relaxation dynamics of pyrrole in the protic water and methanol solvents, by fs transient absorption methods. The only species found after excitation, at different wavelengths from the onset of the electronic absorption, are solvated pyrrole cations and electrons. The study aims to unravel the photoionization route, characterize the intermediate species and understand the role played by the specific interactions established between the pyrrole N-H group and the water and methanol solvent molecules.