Time-resolved spectroscopic studies of hydrogen abstraction and decarboxylation reactions of selected benzophenone derivatives

TL;DRAbstract

Nanosecond time-resolved resonance Raman spectroscopy (ns-TR3), nanosecond transient absorption (ns-TA) and femtosecond transient absorption (fs-TA) were utilized to investigate the photochemistry of ketoprofen (KP), ketoprofen-purine dyads, fenofebric acid (FA) in different solutions. \n\n\n\nFor KP, the rate constant and reaction mechanism of KP are strongly dependent on the concentration of water. In neat acetonitrile and acetonitrile-rich solutions (water:acetonitrile?1:1, v:v), KP exhibits mostly benzophenone-like photochemistry to give rise to triplet state which in turn transforms to ketyl radical intermediate by hydrogen abstraction reaction. However, in aqueous solutions with higher water ratios (water:acetonitrile?80%) or acidic solutions, fs-TA studies found that after the irradiation of KP the singlet state will transform into the triplet state with a high efficiency through an intersystem crossing and a triplet state mediated decarboxylation reaction of KP is confirmed in

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