Mapping the UV photophysics of platinum metal complexes bound to nucleobases: Laser spectroscopy of isolated Uracil·pt(CN)42- and Uracil·Pt(CN)62- complexes

Ananya Sen, Caroline E H Dessent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report the first UV laser spectroscopic study of isolated gas-phase complexes of platinum metal complex anions bound to a nucleobase as model systems for exploring at the molecular level the key photophysical processes involved in photodynamic therapy. Spectra of the PtIV(CN)62-·Ur and PtII(CN)42-·Ur complexes were acquired across the 220-320 nm range using mass-selective photodepletion and photofragment action spectroscopy. The spectra of both complexes reveal prominent UV absorption bands (max = 4.90 and 4.70 eV) that we assign primarily to excitation of the Ur localized chromophore. Distinctive UV photofragmentation products are observed for the complexes, with PtIV(CN)62-·Ur photoexcitation resulting in complex fission, while PtII(CN)42-·Ur photoexcitation initiates a nucleobase proton-transfer reaction across 4.4-5.2 eV and electron detachment above 5.2 eV. The observed photofragments are consistent with ultrafast decay of a Ur localized excited state back to the electronic ground state followed by intramolecular vibrational relaxation and ergodic complex fragmentation.

Original languageEnglish
Pages (from-to)3281-3285
Number of pages5
Issue number19
Publication statusPublished - 2 Oct 2014


  • laser photodissociation
  • multiply charged anions
  • nucleobase photochemistry
  • photodynamic therapy
  • Pt complex photochemistry
  • uracil photophysics

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