Radiationless intermolecular singlet-triplet energy transfer in chlorophyll-a: tool for investigation of non-phosphorescing triplet states

1974 ◽  
Vol 26 (1) ◽  
pp. 45-49 ◽  
Author(s):  
E.R. Menzel
Keyword(s):  
Energy Transfer ◽  
Chlorophyll A ◽  
Triplet States ◽  
Triplet Energy ◽  
Triplet Energy Transfer

scholarly journals Evidence for water-mediated triplet–triplet energy transfer in the photoprotective site of the peridinin–chlorophyll a–protein

2014 ◽  
Vol 1837 (1) ◽  
pp. 85-97 ◽  
Author(s):  
Marilena Di Valentin ◽  
Claudia E. Tait ◽  
Enrico Salvadori ◽  
Laura Orian ◽  
Antonino Polimeno ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Chlorophyll A ◽  
Triplet Energy ◽  
Triplet Energy Transfer

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

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