Gas-Phase Interactions between Lead(II) Ions and Cytosine: Tandem Mass Spectrometry and Infrared Multiple-Photon Dissociation Spectroscopy Study

Jean-Yves Salpin (1) , Violette Haldys (1) , Sébastien Guillaumont (1) , Jeanine Tortajada (1) , Marcela Hurtado (2) , Al Mokhtar Lamsabhi (2)

1 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement
2 Departemento de Química C-9

Gas-phase interactions between Pb²⁺ ions and cytosine (C) were studied by combining tandem mass spectrometry, infrared multiple photon dissociation spectroscopy, and density functional theory (DFT) calculations. Both singly and doubly charged complexes were generated by electrospray. The [Pb(C)−H]⁺ complex was extensively studied, and this study shows that two structures, involving the interaction of the metal with the deprotonated canonical keto-amino tautomer of cytosine, are generated in the gas phase; the prominent structure is the bidentate form involving both the N1 and O2 electronegative centers. The DFT study also points out a significant charge transfer from the nucleobase to the low-lying p orbitals of the metal and a strong polarization of the base upon complexation. The various potential energy surfaces explored to account for the fragmentation observed are consistent with the high abundance of the [PbNH₂]⁺ fragment ion.

Mots clés: density functional calculations; gas‐phase reactions; IRMPD spectroscopy; lead cationization; mass spectrometry

Domaines: Chimie-Physique [physics.chem-ph]

Jean-Yves Salpin, Violette Haldys, Sébastien Guillaumont, Jeanine Tortajada, Marcela Hurtado, et al.. Gas-Phase Interactions between Lead(II) Ions and Cytosine: Tandem Mass Spectrometry and Infrared Multiple-Photon Dissociation Spectroscopy Study. ChemPhysChem, 2014, 15 (14), pp.2959-2971. ⟨10.1002/cphc.201402369⟩. ⟨hal-01221270⟩