Theoretical Studies of Thymine–Thymine Photodimerization: Using Ground State Dynamics to Model Photoreaction

Martin McCullagh, George C Schatz

Research output: Chapter in Book/Report/Conference proceedingChapter


Excited electronic states of DNA are extremely important in biology and yet most of these states have lifetimes of ∼ 1 ps. This short lifetime allows for very little nuclear rearrangement during dissipation. In particular, photoinduced thymine-thymine (TT) dimer formation has been found to be a picosecond process. The most prevalent TT dimer is formed by a [2+2] addition of the C5–C6 double bonds of the dimerizing thymines. Given the topochemical rules known for photoinduced [2+2] addition of organic compounds in the solid state, a similar set of rules is presented for TT dimerization in solution phase DNA. It is found that a single ground state geometric parameter (the distance, d,between the C5–C6 double bonds) is sufficient as a constraint on when dimers can form such that accurate TT dimer quantum yields can be predicted. The electronic basis of such a model is examined along with calibration of the model for dT20 and dA20dT20. The application and validity of this model to a variety of double and single stranded DNA systems is then discussed.
Original languageEnglish (US)
Title of host publicationPractical Aspects of Computational Chemistry I
Subtitle of host publicationAn Overview of the Last Two Decades and Current Trends
EditorsJerzy Leszczynski, Manoj Shukla
PublisherSpringer Netherlands
Number of pages29
ISBN (Electronic)978-94-007-0919-5
ISBN (Print)978-94-007-0918-8, 978-94-007-9771-0
StatePublished - 2012


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