We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases.
- Authors
Szabla, Rafał; Góra, Robert W.; Šponer, Jiří; Šponer, Judit E.
- Abstract
The photoinduced isomerization of diaminomaleonitrile (DAMN) to diaminofumaronitrile (DAFN) was suggested to play a key role in the prebiotically plausible formation of purine nucleobases and nucleotides. In this work we analyze two competitive photoisomerization mechanisms on the basis of state-of-the-art quantum-chemical calculations. Even though it was suggested that this process might occur on the triplet potential-energy surface, our results indicate that the singlet reaction channel should not be disregarded either. In fact, the peaked topography of the S1/S0 conical intersection suggests that the deexcitation should most likely occur on a sub-picosecond timescale and the singlet photoisomerization mechanism might effectively compete even with a very efficient intersystem crossing. Such a scenario is further supported by the relatively small spin-orbit coupling of the S1 and T2 states in the Franck-Condon region, which does not indicate a very effective triplet bypass for this photoreaction. Therefore, we conclude that the triplet reaction channel in DAMN might not be as prominent as was previously thought.
- Subjects
PHOTOISOMERIZATION; PREBIOTICS; PURINE nucleotides; BASE pairs; FRANCK-Condon principle
- Publication
Chemistry - A European Journal, 2014, Vol 20, Issue 9, p2515
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201304224