Investigating the ultrafast dynamics and long-term photostability of an isomer pair, Usujirene and Palythene, from the Mycosporine-like amino acid family
Whittock, Abigail L, Wooley, Jack Matthew, Auckloo, Nazia, Corre, Christophe and Stavros, Vasilos G
Using a combination of natural product extraction/purification and femtosecond transient absorption spectroscopy, we studied the relaxation pathway for a common mycosporine-like amino acid pair, usujirene and its geometric isomer palythene, in the first few nanoseconds following photoexcitation. Our studies show that the electronic excited state lifetimes of these molecules persist for only a few hundred femtoseconds before the excited state population is funneled through an energetically accessible conical intersection with subsequent vibrational energy transfer to the solvent. We found that a minor portion of the isomer pair did not recover to their original state within 3 ns after photoexcitation.