%0 Journal Article %T Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides %+ Dynamique et Interactions en phase Condensée (DICO) %+ CNR – Istituto di Biostrutture e Bioimmagini %A Martinez-Fernandez, Lara %A Improta, Roberto %< avec comité de lecture %J Photochemical & Photobiological Sciences %I Springer %V 17 %N 5 %P 586-591 %8 2018 %D 2018 %R 10.1039/C8PP00040A %Z Chemical Sciences/Theoretical and/or physical chemistry %Z Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph]Journal articles %X The excited states involved in the main photodimerization paths in TpdC and dCpT are mapped by PCM/TD-M052X calculations, considering different dinucleotide conformers. As for TT steps, a cyclobutane pyrimidine dimer (CPD) is formed on the PES of the lowest energy exciton, delocalized over two stacked pyrimidines; 6–4 pyrimidine–pyrimidone (64-PP) adduct's formation involves instead a 5′-ter → 3′-ter charge transfer state. For dCpT, 64-PP dimerization occurs via a two-step reaction, which proceeds through an oxetane intermediate. For TpdC, instead, the final 64-PP product is obtained in a single step and it is as stable as the CPD photoproduct, explaining the relatively large yield of 64-PP found experimentally for TC steps in DNA. %G English %L cea-01978125 %U https://cea.hal.science/cea-01978125 %~ CEA %~ CNRS %~ IRAMIS-LIDYL %~ CEA-UPSAY %~ UNIV-PARIS-SACLAY %~ CEA-UPSAY-SACLAY %~ TEST-HALCNRS %~ GS-ENGINEERING %~ IRAMIS %~ GS-CHIMIE %~ GS-PHYSIQUE %~ INSTITUT-SCIENCES-LUMIERE