TY - JOUR

T1 - Spin effects as a tool to study photoinduced processes in (S/R)-ketoprofen-(S)-N-methylpyrrolidine dyads

AU - Polyakov, Nikolay

AU - Ageeva, Aleksandra

AU - Kiryutin, Alexey

AU - Timoshnikov, Victor

AU - Magin, Ilya

AU - Babenko, Simon

AU - Kuznetsova, Polina

AU - Kruppa, Alexander

AU - Purtov, Peter

AU - Stepanov, Alexandr

AU - Ivanov, Mikhail

AU - Fedin, Matvey

AU - Kuibida, Leonid

AU - Leshina, Tatyana

PY - 2019/12/28

Y1 - 2019/12/28

N2 - (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.

AB - (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.

KW - MAGNETIC-FIELD DEPENDENCE

KW - DYNAMIC NUCLEAR-POLARIZATION

KW - MULTINUCLEAR RADICAL PAIRS

KW - TRIPLET EXCITED-STATE

KW - GREEN-FUNCTION METHOD

KW - ELECTRON-TRANSFER

KW - MODEL CALCULATION

KW - CIDNP

KW - NAPROXEN

KW - PHOTOSENSITIVITY

UR - http://www.scopus.com/inward/record.url?scp=85077326920&partnerID=8YFLogxK

U2 - 10.1063/1.5128043

DO - 10.1063/1.5128043

M3 - Article

C2 - 31893924

AN - SCOPUS:85077326920

VL - 151

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 24

M1 - 245101

ER -