UV-induced proton transfer in 3-amino-1,2,4-triazole

Pagacz-Kostrzewa, Magdalena; Bil, Andrzej; Wierzejewska, Maria

doi:10.1016/j.jphotochem.2016.11.023

Cited by 24 publications

(9 citation statements)

References 35 publications

(41 reference statements)

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“…The N1H → N7H phototautomerization in 7-azaindole is analogous to the UVinduced hydrogen-atom transfers from one heteroatom to the other, which were observed for a number of heterocyclic compounds. [59][60][61][62][63][64][65] For indole, due to the lack of any heteroatom other than N1 in the structure, no species analogous to the N7H-form was photoproduced. The interpretation of the photochemical transformations observed for indole and 7-azaindole strongly corroborate each other.…”

Section: B Photoinduced Transformations Of Indole Monomers Isolated mentioning

confidence: 99%

Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Reva

Lapiński

Jesus

et al. 2017

The Journal of Chemical Physics

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Photochemical transformations were studied for monomers of indole and 3-formylindole isolated in low-temperature noble-gas matrices. Upon UV (λ > 270 nm) irradiation of indole trapped in argon and neon matrices, the initial 1H-form of the compound converted into the 3H-tautomer. Alongside this photoinduced hydrogen-atom transfer, an indolyl radical was also generated by photodetachment of the hydrogen atom from the N1-H bond. Excitation of 3-formylindole isolated in an argon matrix with UV (λ > 335 nm) light led to interconversion between the two conformers of the 1H-tautomer, differing from each other in the orientation of the formyl group (cis or trans). Parallel to this conformational phototransformation, the 3H-form of the compound was generated in the 1H → 3H phototautomeric conversion. The photoproducts emerging upon UV irradiation of indole and 3-formylindole were identified by comparison of their infrared spectra with the spectra calculated for candidate structures.

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Section: B Photoinduced Transformations Of Indole Monomers Isolated mentioning

confidence: 99%

Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Reva

Lapiński

Jesus

et al. 2017

The Journal of Chemical Physics

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“…Another type of phototransformation that may occur through transition state TS3 (Figure ) is 2-TRA1c → 1-TRA1c tautomerization. Several such processes have been recently reported for 3-amino-1,2,4-triazole and indole derivatives. − This type of reaction involves the N–H bond breaking and is expected upon higher energy irradiation, usually with λ < 250 nm. In the present study, no such process was observed despite the exposure of the matrices containing TRA species to higher energy radiation (up to λ= 225 nm) (see Figure S4 for comparison of the experimental spectra with the calculated ones for all possible TRA tautomers).…”

Section: Resultsmentioning

confidence: 99%

Phototransformations of 2-(1,2,4-Triazol-3-yl)benzoic Acid in Low Temperature Matrices

et al. 2019

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Phototransformations of 2-(1,2,4-triazol-3-yl)benzoic acid induced by tunable UV laser were studied in low temperature matrices by FTIR spectroscopy. Out of 36 possible isomers of this molecule the most stable one, comprising the intramolecular N−H•••O hydrogen bond, was detected experimentally in argon and xenon matrices after deposition. Upon irradiation with λ = 325 nm, two new conformers of the precursor were formed. The corresponding reverse photorotamerizations were also detected at 250 nm partly reproducing the initial molecules. In addition to the conformational changes, an interesting photoisomerization took place in the studied matrices leading to a proton transfer from N atom of the triazole ring to the carbonyl oxygen of the carboxylic group. As a result of this reaction, a new product with two OH groups was identified for the first time. The experimental studies were supported by DFT calculations in both ground and excited electronic states.

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“…Phototautomerization processes belonging to this category were observed for the compounds isolated in the matrices of solid Ar (or other noble gases) as well as in the matrices of solid N 2 . 6 − 29 It appears that the UV-induced oxo → hydroxy, thione → thiol, or N( i )H → N( j )H hydrogen-atom transfer leading to the change of tautomeric form (phototautomerism) is a typical pattern of the photochemical behavior of monomeric heterocyclic compounds isolated in low-temperature Ar, Xe, Ne, or N 2 matrices. Such phototautomeric reactions may proceed either by a mechanism involving detachment of a hydrogen atom followed by its association to another heteroatom or by a purely intramolecular mechanism involving a shift of a hydrogen atom that occurs during dissipation of the excitation energy, when the molecule is in highly excited vibrational levels of the ground electronic state.…”

Section: Introductionmentioning

confidence: 99%

Effect of a Solid-Hydrogen Environment on UV-Induced Hydrogen-Atom Transfer in Matrix-Isolated Heterocyclic Thione Compounds

et al. 2021

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To shed more light on the mechanisms of UV-induced hydrogen-atom-transfer processes in heterocyclic molecules, phototautomeric thione → thiol reactions were investigated for thione compounds isolated in low-temperature Ar as well as in n-H 2 (normal hydrogen) matrices. These studies concerned thione compounds with a five-membered heterocyclic ring and thione compounds with a six-membered heterocyclic ring. The experimental investigation of 2-thioimidazole and 3-thio-1,2,4-triazole (thione compounds with a five-membered heterocyclic ring) revealed that for the compounds isolated in solid n-H 2 only trace amounts of thiol photoproducts were photogenerated; even though for the same compounds isolated in the solid Ar matrix, the thione → thiol photoconversion was nearly total. In contrast to that, for 3-thiopyridazine and 2-thioquinoline (thione compounds with a six-membered heterocyclic ring) isolated in solid n-H 2 , the UV-induced thione → thiol conversion occurred with the yield reaching 25–50% of the yield of the analogous process observed for the same species isolated in solid Ar. The obtained experimental results allow us to conclude that the dissociation–association mechanism nearly exclusively governs the phototransformation in thione heterocycles with high barriers for tautomerization (such as thione compounds with a five-membered ring), whereas the strictly intramolecular hydrogen-atom shift contributes to the mechanism of hydrogen-atom transfer in thione heterocycles with lower barriers (such as thione compounds with a six-membered ring).

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UV-induced proton transfer in 3-amino-1,2,4-triazole

Cited by 24 publications

References 35 publications

Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Photoinduced transformations of indole and 3-formylindole monomers isolated in low-temperature matrices

Phototransformations of 2-(1,2,4-Triazol-3-yl)benzoic Acid in Low Temperature Matrices

Effect of a Solid-Hydrogen Environment on UV-Induced Hydrogen-Atom Transfer in Matrix-Isolated Heterocyclic Thione Compounds

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