| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Time-Resolved Resonance Raman and Density Functional TheoryStudy of the Deprotonation Reaction of the Triplet State ofp-Hydroxyacetophenone in Water Solution
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Picosecond and nanosecond time-resolved resonance Raman (TR3) spectroscopy was employed toinvestigate the deprotonation/ionization reaction of p-hydroxyacetophenone (HA) after ultravioletphotolysis in water solution. The TR3 spectra in conjunction with density functional theory (DFT)calculations were used to characterize the structure and dynamics of the excited-state HAdeprotonation to form HA anions in near neutral water solvent. DFT calculations based on a solute−solvent intermolecular H-bonded complex model containing up to three water molecules were usedto evaluate the H-bond interactions and their influence on the deprotonation reaction and thestructures of the intermediates. The deprotonation reaction was found to occur on the tripletmanifold with a planar H-bonded HA triplet complex as the precursor species. The HA triplet speciesis generated within several picoseconds and then decays with a ∼10 ns time constant to producethe HA triplet anion species after 267 nm photolysis of HA in water solution. The triplet anionspecies was observed to decay with a time constant of about 90 ns into the ground-state anionspecies that was found to have a lifetime of about 200 ns. The DFT calculations on the H-bondedcomplexes of the anion triplet and ground-states species suggest that these anion species areH-bonded complexes with planar quinonoidal structures containing two water molecules H-bonded,respectively, with oxygen lone pairs of the carbonyl and deprotonated hydroxyl moieties. Adeactivation scheme of the photoexcited HA in regard to the deprotonation reaction in neutralwater solutions was proposed. With the above dynamic and structural information available, webriefly discuss the possible implications of the model HA photochemistry in water solutions for thephotodeprotection reactions of related p-HP phototrigger compounds in aqueous solutions.
|
| article type
| |
| is part of this journal
| |
