title: Ultrafast Electronic Deactivation Dynamics of Xanthosine Monophosphate.
abstract: Ultrafast energy dissipation is a crucial factor for the photostability of DNA and RNA, but even some of the key electronic deactivation pathways in monomeric nucleic acid building stones are still controversial. Here, we report on the excited-state dynamics of the rare nucleotide xanthosine monophosphate as a function of deprotonation state (XMP vs. XMP - ) and excitation wavelength ( λ pump = 278-243 nm) by femtosecond time-resolved fluorescence and absorption spectroscopy. We show that the predominating relaxation channel leads to a return of the photo-excited molecules to the electronic ground state inτ∼1 ps. The mechanism likely involves an out-of-plane deformation of the five-membered ring, different from the main electronic deactivation pathways in the canonical purine bases adenine and guanine. The results are discussed in terms of the structural and electronic differences of XMP compared to the canonical nucleotides.
authors.affiliation: Institute of Physical Chemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany. katharina.roettger@gmail.com.|Centre for Process Innovation, Wilton Centre, Wilton, Redcar TS10 4RF, UK. katharina.roettger@gmail.com.
authors.forename: Katharina
authors.initials: K
authors.lastname: Röttger
authors.affiliation: Institute of Physical Chemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany. stellmacher@phc.uni-kiel.de.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Stellmacher
authors.affiliation: Institute of Physical Chemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany. mayra.stuhldreier@gmx.de.
authors.forename: Mayra C
authors.initials: MC
authors.lastname: Stuhldreier
authors.affiliation: Institute of Physical Chemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany. temps@phc.uni-kiel.de.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Temps
mesh_terms: D000225:Adenine / Q000737:chemistry*; D004583:Electrons; D006147:Guanine / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D055668:Photochemical Processes; D011522:Protons; D012265:Ribonucleotides / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D019820:Xanthine
chemical_list: D011522:Protons; D012265:Ribonucleotides; D019820:Xanthine; C011141:xanthosine monophosphate; D006147:Guanine; D000225:Adenine
keywords: DNA; RNA; XMP; biophysics; fluorescence up-conversion; transient absorption; ultrafast photochemistry; xanthosine monophosphate