Spin effects as a tool to study photoinduced processes in (S/R)-ketoprofen-(S)-N-methylpyrrolidine dyads

Nikolay Polyakov, Aleksandra Ageeva, Alexey Kiryutin, Victor Timoshnikov, Ilya Magin, Simon Babenko, Polina Kuznetsova, Alexander Kruppa, Peter Purtov, Alexandr Stepanov, Mikhail Ivanov, Matvey Fedin, Leonid Kuibida, Tatyana Leshina

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

(S/R)-Ketoprofen (KP) is considered to be the strongest photosensitizer among nonsteroidal anti-inflammatory drugs. The photosensitizing reactions are caused by a substituted benzophenone chromophore. It produces various toxic effects through the formation of active paramagnetic intermediates and photoproducts able to attack biological substrates. Photoinduced transformations of KP have been extensively studied in order to identify paramagnetic intermediates. Considerable attention is also paid to photoinduced processes in dyads, where KP is linked with chiral partners, since such processes believed to model the binding of chiral drugs with enzymes and receptors. In the present study, the dyads containing (S)/(R)-KP covalently linked with (S)-N-methylpyrrolidine have been synthesized to examine the peculiarities of photoinduced electron transfer (ET) and hydrogen transfer (HT) in chiral systems. To detect short-lived paramagnetic intermediates, in dyad's excited triplet state, such as biradical zwitter ion (BZI) and neutral biradical (BR), spin chemistry methods [chemically induced dynamic nuclear polarization (CIDNP) and chemically induced dynamic electron polarization (CIDEP) in arbitrary magnetic fields], allowing indirect detection of transient paramagnetic particles by NMR, have been utilized. Both mentioned processes have been found to begin with the excitation of KP into the triplet state followed by the formation of BZI for ET and BR for HT, respectively. Products of stereoselective attachment of the N-methylpyrrolidine residue to the carbonyl carbon atom of KP occurring in both BZI and BR have been detected by NMR spectral analysis. The value of electronic exchange interaction in biradicals has been determined from the position of the characteristic maximum of hyperpolarization in the CIDNP magnetic field dependences.

Original languageEnglish
Article number245101
Number of pages10
JournalJournal of Chemical Physics
Volume151
Issue number24
DOIs
Publication statusPublished - 28 Dec 2019

Keywords

  • MAGNETIC-FIELD DEPENDENCE
  • DYNAMIC NUCLEAR-POLARIZATION
  • MULTINUCLEAR RADICAL PAIRS
  • TRIPLET EXCITED-STATE
  • GREEN-FUNCTION METHOD
  • ELECTRON-TRANSFER
  • MODEL CALCULATION
  • CIDNP
  • NAPROXEN
  • PHOTOSENSITIVITY

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