Photoelectron spectroscopic and density functional theoretical studies of the 2'-deoxycytidine homodimer radical anion.

The intact (parent) 2'-deoxycytidine homodimer anion, (dC)2 (●-), was generated in the gas phase (in vacuo) using an infrared desorption∕photoemission source and its photoelectron spectrum was recorded using a pulsed, magnetic bottle photoelectron spectrometer. The photoelectron spectrum (PES) revealed a broad peak with the maximum at an electron binding energy between 1.6 and 1.

Local excitation of the 5-bromouracil chromophore in DNA. Computational and UV spectroscopic studies.

The UV electronic transition energies and their oscillator strengths for two stacked dimers having B-DNA geometries and consisting of 5-bromouracil ((Br)U) and a purine base were studied at the MS-CASPT2/6-311G(d) level with an active space of 12 orbitals and 12 electrons. The calculated energy of the first vertical (π,π*) transitions for the studied dimers remain in fair agreement with the maxima in the difference spectra measured for duplexes with the 5'-A(Br)U-3' or 5'-G(Br)U-3' sequences. Our MS-CASPT2 results show that the charge transfer (CT) states in which an electron is transferred from A/G to (Br)U are located at much higher energies than the first (π,π*) transitions, which involve local excitation (LE) of (Br)U.

The anionic (9-methyladenine)-(1-methylthymine) base pair solvated by formic acid. A computational and photoelectron spectroscopy study.

The photoelectron spectrum for (1-methylthymine)-(9-methyladenine)...