Chemical evolution. III. Photochemical conversion of enaminonitriles to imidazoles

Ferris, James P.; Kuder, James E.

doi:10.1021/ja00711a051

Cited by 41 publications

(40 citation statements)

References 2 publications

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“…[14,15] According to Waldeck, [16] there exist two main types of cis-trans photoisomerization mechanisms through either singlet or triplet states. The mechanism through the triplet manifold was also supported by the triplet sensitizing experiments of Ferris et al [1] Numerous examples of singlet cis-trans photoisomerization mechanisms have been described to this day. According to Levine and Martínez, [17] two molecular coordinates dominate the photodynamics of any isomerizing system.…”

Section: Introductionmentioning

confidence: 73%

“…Among the suggested routes, much attention has been paid to the formation of purines through oligomerization of hydrogen cyanide. [1][2][3][4][5][6] Diaminomaleonitrile (DAMN) is one of the most interesting intermediates among the multitude of organic compounds formed in this synthesis. It has been shown that the generation of nucleobases through DAMN ( Figure 1) might also occur in formamide solutions.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, even if inaccessible, this particular mechanism can be triggered in the presence of the so-called sensitizers as was observed in several photoisomerizing systems. [1,[28][29][30][31] In contrast to the singlet mechanism, the ISC between the 3 pp* state and the electronic ground state is an nÀ1-dimensional crossing seam, and there is only one molecular coordinate that is indispensable for this process: [32] the twisting motion about the C=C bond.…”

Section: Introductionmentioning

confidence: 99%

“…[33] Furthermore, no mechanistic insight has been provided for the triplet mechanism, which was suggested by Ferris et al [1] as the primary radiationless deexcitation channel. Therefore, in this work we present a detailed description of these two competitive deactivation processes, which are responsible for the DAMN-to-DAFN photoisomerization.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases

Szabla

Góra

Šponer

et al. 2014

Chemistry A European J

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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.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Molecular Mechanism of Diaminomaleonitrile to Diaminofumaronitrile Photoisomerization: An Intermediate Step in the Prebiotic Formation of Purine Nucleobases

Szabla

Góra

Šponer

et al. 2014

Chemistry A European J

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show abstract

“…Imidazole has been shown to be a prebiotic compound (Ferris and Kuder, 1970;Or6 et al, 1984;Fen'is, et al, 1968) and is widely used as an activating group for the synthesis of RNA and DNA from nucleotides . Imidazole was investigated in 0.15 M solution at both 100°C and 80°C.…”

Section: Imidazoiementioning

confidence: 99%