title: Spectroscopic and theoretical investigations of adenosine 5'-diphosphate and adenosine 5'-triphosphate dianions in the gas phase.
abstract: Doubly deprotonated adenosine 5'-diphosphate ([ADP-2H](2-)) and adenosine 5'-triphosphate ([ATP-2H](2-)) dianions were investigated using infrared multiple photon dissociation (IR-MPD) and photoelectron spectroscopy. Vibrational spectra acquired in the X-H stretch region (X = C, N, O) and augmented by isotope-labelling were compared to density functional theory (DFT) calculations at the B3LYP/TZVPP level. This suggests that in [ATP-2H](2-) the two phosphate groups adjacent to the ribose ring are preferentially deprotonated. Photoelectron spectra recorded at 4.66 and 6.42 eV photon energies revealed adiabatic detachment energies of 1.35 eV for [ADP-2H](2-) and 3.35 eV for [ATP-2H](2-). Repulsive Coulomb barriers were estimated at ~2.2 eV for [ADP-2H](2-) and ~1.9 eV for [ATP-2H](2-). Time-dependent DFT calculations have been used to simulate the photoelectron spectra. Photodetachment occurs primarily from lone pair orbitals on oxygen atoms within the phosphate chain.
authors.affiliation: Institut für Physikalische Chemie, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schinle
authors.forename: Paul E
authors.initials: PE
authors.lastname: Crider
authors.forename: Matthias
authors.initials: M
authors.lastname: Vonderach
authors.forename: Patrick
authors.initials: P
authors.lastname: Weis
authors.forename: Oliver
authors.initials: O
authors.lastname: Hampe
authors.forename: Manfred M
authors.initials: MM
authors.lastname: Kappes
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D005740:Gases / Q000737:chemistry*; D006860:Hydrogen Bonding; D008962:Models, Theoretical; D056951:Photoelectron Spectroscopy; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000838:Anions; D005740:Gases; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate