title: Long-Lived Excited-State Dynamics of i-Motif Structures Probed by Time-Resolved Infrared Spectroscopy.
abstract: UV-generated excited states of cytosine (C) nucleobases are precursors to mutagenic photoproduct formation. The i-motif formed from C-rich sequences is known to exhibit high yields of long-lived excited states following UV absorption. Here the excited states of several i-motif structures have been characterized following 267 nm laser excitation using time-resolved infrared spectroscopy (TRIR). All structures possess a long-lived excited state of ∼300 ps and notably in some cases decays greater than 1 ns are observed. These unusually long-lived lifetimes are attributed to the interdigitated DNA structure which prevents direct base stacking overlap.
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK. p.keane@reading.ac.uk.
authors.forename: Páraic M
authors.initials: PM
authors.lastname: Keane
authors.affiliation: School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Frederico R
authors.initials: FR
authors.lastname: Baptista
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.|Diamond Light Source, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK.
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Gurung
authors.affiliation: School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Devereux
authors.affiliation: Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK.
authors.forename: Igor V
authors.initials: IV
authors.lastname: Sazanovich
authors.affiliation: Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.affiliation: Department of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
authors.forename: John A
authors.initials: JA
authors.lastname: Brazier
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Cardin
authors.affiliation: School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: John M
authors.initials: JM
authors.lastname: Kelly
authors.affiliation: School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland. susan.quinn@ucd.ie.
authors.forename: Susan J
authors.identifier: 0000-0002-7773-8842
authors.initials: SJ
authors.lastname: Quinn
mesh_terms: D002942:Circular Dichroism; D007700:Kinetics; D009711:Nucleotides / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009711:Nucleotides
keywords: DNA; cytosine; excited states; i-motifs; time-resolved infrared spectroscopy