title: A time-resolved spectroscopy and density functional theory study of the solvent dependent photochemistry of fenofibric acid.
abstract: The solvent dependent photochemistry of fenofibric acid (FA) was studied by femtosecond transient absorption and nanosecond time-resolved resonance Raman experiments and density functional theory calculations. In acetonitrile-rich solution, a typical nπ* triplet state FA ((3)FA) is formed through a highly efficient intersystem crossing and then the (3)FA species undergoes some reaction with water to generate a ketyl radical intermediate at low water concentrations. In contrast, nπ* (3)FA changes from a reaction with water to generate a ketyl radical intermediate at lower water concentrations to a decarboxylation reaction with the assistance of water molecules to produce a biradical intermediate at higher water concentrations in water-rich solutions. The decarboxylation reaction leads to the formation of the FA carbanion in 50% phosphate buffer solution and the FA carbanion is observed on the picosecond to nanosecond time scale and the cleavage of the FA carbanion gives rise to the enolate 3(-) anion at later nanosecond delay times. As regards fenofibrate (FB), it only exhibits a benzophenone-like photochemistry, which consists of some reaction with water to generate a ketyl radical intermediate, being observed in the different aqueous solutions.
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China.
authors.forename: Ming-De
authors.initials: MD
authors.lastname: Li
authors.forename: Jiani
authors.initials: J
authors.lastname: Ma
authors.forename: Tao
authors.initials: T
authors.lastname: Su
authors.forename: Mingyue
authors.initials: M
authors.lastname: Liu
authors.forename: David Lee
authors.initials: DL
authors.lastname: Phillips
mesh_terms: D000042:Absorption; D000097:Acetonitriles / Q000737:chemistry; D011345:Fenofibrate / Q000031:analogs & derivatives* / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D012997:Solvents; D014867:Water; C006012:fenofibric acid; D011345:Fenofibrate; C032159:acetonitrile