Structures of [M(Ura-H)(Ura)]⁺ and [M(Ura-H)(H₂O)_n]⁺ (M = Cu, Zn, Pb; n = 1–3) complexes in the gas phase by IRMPD spectroscopy in the fingerprint region and theoretical studies

Barry Power (1) , Violette Haldys (2) , Jean-Yves Salpin (2) , Travis D Fridgen (1)

1 MUN - Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada]
2 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement

The gas-phase structures of the bare dimers, [M(Ura-H)(Ura)]⁺, and hydrated monomers, [M(Ura-H)(H₂O)_n]⁺, were examined using infrared multiple photon dissociation spectroscopy in the fingerprint region (1000 cm⁻¹–1900 cm⁻¹) for M = Cu, Zn, and Pb and n = 1–3. The experimental results were compared to those calculated using density functional methods The dimeric structures all show deprotonation of one uracil moiety at N3, and forms a tetracoordinate interaction with N3 and O4 of the deprotonated uracil, and N3 and O2 of the neutral uracil. The hydrated monomers, [M(Ura-H)(H₂O)]⁺, all have rather different structures. Uracil is deprotonated at N3 for M = Zn and Pb, but for Cu, uracil is deprotonated at N1 and Cu²⁺ is bound to N1 and O2. Like the [M(Ura-H)(Ura)]⁺ complexes, in [Pb(Ura-H)(H₂O)]⁺ the metal is bound to N3 and O4. The Zn²⁺ complex actually better resembles [M(Ura)(OH)]⁺ with a proton apparently transferred from water to O4 of uracil and the metal cation coordinated to O2. Unlike the singly hydrated complex, uracil is deprotonated at N3 in [Cu(Ura-H)(H₂O)₂]⁺. In all singly, doubly, and triply solvated complexes studied, water is found to be coordinated to the metal cation.

Mots clés: Uracil; DNA base; Ion–molecule complex; IRMPD spectroscopy; Metal cation

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

Barry Power, Violette Haldys, Jean-Yves Salpin, Travis D Fridgen. Structures of [M(Ura-H)(Ura)]⁺ and [M(Ura-H)(H₂O)_n]⁺ (M = Cu, Zn, Pb; n = 1–3) complexes in the gas phase by IRMPD spectroscopy in the fingerprint region and theoretical studies. International Journal of Mass Spectrometry, 2018, 429, pp.56 - 65. ⟨10.1016/j.ijms.2017.05.003⟩. ⟨hal-01889158⟩