Open AccessElectrophilic Properties of 2′-Deoxyadenosine···Thymine Dimer: Photoelectron Spectroscopy and DFT Studies
Author(s) -
Piotr Storoniak,
Janusz Rak,
Haopeng Wang,
Yeon Jae Ko,
Kit H. Bowen
Publication year - 2021
Publication title -
the journal of physical chemistry. a/the journal of physical chemistry. a.
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 235
eISSN - 1520-5215
pISSN - 1089-5639
DOI - 10.1021/acs.jpca.1c03803
Subject(s) - chemistry , thymine , dimer , binding energy , ion , x ray photoelectron spectroscopy , deoxyadenosine , photochemistry , electron transfer , atomic physics , nuclear magnetic resonance , dna , biochemistry , physics , organic chemistry , adenosine
The anion radical of the 2'-deoxyadenosine···thymine (dAT •- ) pair has been investigated experimentally and theoretically in the gas phase. By employing negative-ion photoelectron spectroscopy (PES), we have registered a spectrum typical for the valence-bound anion, featuring a broad peak at the electron-binding energy (EBE) between ∼1.5 and 2.2 eV with the maximum at ∼1.9 eV. The measured value of the adiabatic electron affinity (AEA) for dAT was estimated to be ∼1.1 eV. Calculations performed at the M06-2X/6-31++G(d,p) level revealed that the structure, where thymine is coordinated to the sugar of dA by two hydrogen bonds, is responsible for the observed PES signal. The AEA G and the vertical detachment energy of 0.91 and 1.68 eV, respectively, calculated for this structure reproduce the experimental values well. The role of the possible proton transfer in the stabilization of anionic radical complexes is discussed.