Gas-Phase Ion Chemistry of Metalloporphyrin Anions with Molecular Oxygen: Probing the Influence of the Oxidation and Spin State of the Central Transition Metal by Experiment and Theory.
Tatjana ArchipovJustin K KirklandKonstantinos D VogiatzisAnnika SteinerGereon Niedner-SchatteburgPatrick WeisKarin FinkOliver HampeManfred M KappesPublished in: The journal of physical chemistry. A (2018)
We performed a comprehensive gas-phase experimental and quantum-chemical study of the binding properties of molecular oxygen to iron and manganese porphyrin anions. Temperature-dependent ion-molecule reaction kinetics as probed in a Fourier-transform ion-cyclotron resonance mass spectrometer reveal that molecular oxygen is bound by, respectively, 40.8 ± 1.4 and 67.4 ± 2.2 kJ mol-1 to the FeII or MnII centers of isolated tetra(4-sulfonatophenyl)metalloporphyrin tetraanions. In contrast, FeIII and MnIII trianion homologues were found to be much less reactive-indicating an upper bound to their dioxygen binding energies of 34 kJ mol-1. We modeled the corresponding O2 adsorbates at the density functional theory and CASPT2 levels. These quantum-chemical calculations verified the stronger O2 binding on the FeII or MnII centers and suggested that O2 binds as a superoxide anion.
Keyphrases
- density functional theory
- molecular dynamics
- transition metal
- ionic liquid
- single molecule
- energy transfer
- molecular dynamics simulations
- magnetic resonance
- high resolution
- hydrogen peroxide
- dna binding
- photodynamic therapy
- computed tomography
- single cell
- electron transfer
- mass spectrometry
- dna methylation
- contrast enhanced