"0947-6539" . "9" . . . . "\u0160ponerov\u00E1, Judit" . . "[4CC4C67C0D04]" . . "RIV/00216224:14740/14:00075641" . . "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 S-1/S-0 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 S-1 and T-2 states in the Franck-Condon region, which does not indicate a very effective triplet bypass for this photoreaction."@en . "Szabla, Rafal Kazimierz" . . "20" . . "4"^^ . . "Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases"@en . . "RIV/00216224:14740/14:00075641!RIV15-MSM-14740___" . . . "Chemistry - A European Journal" . "000331729700018" . "http://onlinelibrary.wiley.com/doi/10.1002/chem.201304224/pdf" . "10.1002/chem.201304224" . "14740" . . "Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases" . "2"^^ . . "7"^^ . . . "Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases" . "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 S-1/S-0 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 S-1 and T-2 states in the Franck-Condon region, which does not indicate a very effective triplet bypass for this photoreaction." . "DE - Spolkov\u00E1 republika N\u011Bmecko" . . . "Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases"@en . "G\u00F3ra, Robert W." . "I, P(ED1.1.00/02.0068), P(GAP208/10/2302)" . . . "30292" . "isomerization; nucleobases; nucleotides; photochemistry; quantum chemistry"@en . "\u0160poner, Ji\u0159\u00ED" .