Dual Time-Scale Proton Transfer and High-Energy, Long-Lived Excitons Unveiled by Broadband Ultrafast Time-Resolved Fluorescence in Adenine-Uracil RNA Duplexes

Ruth Chau Ting Chan, Chensheng Ma, Allen Ka Wa Wong, Chris Tsz Leung Chan, Joshua Chiu Lok Chow, Wai Ming Kwok

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)

Abstract

In contrast to the immense amount of research on electronically excited DNA, surprisingly little has been done about the excited states of RNA. Herein, we demonstrate an ultrafast broadband time-resolved fluorescence and fluorescence anisotropy study to probe directly the intrinsic fluorescence and overall dynamics of the fluorescence from a homopolymeric adenine·uracil RNA duplex adopting the A-form structure. The results unveiled complex deactivation through distinctive multichannels mediated by states of varied energy, a character of charge transfer, and a lifetime from sub-picosecond to nanoseconds. In particular, we observed an unprecedented kinetic isotopic effect and participation of unusual proton transfer from states in two discrete energies and time domains. We also identified a high-energy nanosecond emission that we attributed to its fluorescence anisotropy to long-lived weakly emissive excitons not reported in DNA. These distinguishing features originate from the stacking, pairing, and local hydration environment specific to the A-form conformation of the adenine·uracil double helix.

Original languageEnglish
Pages (from-to)302-311
Number of pages10
JournalJournal of Physical Chemistry Letters
Volume13
Issue number1
DOIs
Publication statusPublished - 13 Jan 2022

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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