Extended Hückel calculations on the conformation and structure of thymine photodimers

Frank Jordan, Bernard Pullman

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7 Scopus citations


Extended Hückel calculations have been performed for the structure of C5-C6 dihydrouracil and thymine and for the uracil and thymine photodimers. The results indicate, in agreement with experiment, that the most stable conformation of the dihydropyrimidines should be the half-chair one. The preferred conformations of the dimers should correspond to planar bases forming an angle of 120° with the cyclobutane ring. The most stable dimers, per se, appear to be the trans-anti and the trans-syn ones in the case of uracil and the cis-anti and the trans-anti ones in the case of thymine. Other factors than inherent stability must play a decisive role in the production of the dimers under specific conditions. When a semi-empirical reduction is carried out upon their absolute values the dipole moments predicted for the different conformers of the thymine dimer agree very satisfactorily with experiment.

Original languageEnglish (US)
Pages (from-to)423-434
Number of pages12
JournalTheoretica Chimica Acta
Issue number5
StatePublished - Jan 1968
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chiropractics


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