Conformational Behavior and Tautomer Selective Photochemistry in Low Temperature Matrices: The Case of 5-(1<i>H</i>-Tetrazol-1-yl)-1,2,4-triazole

Pagacz-Kostrzewa, Magdalena; Reva, Igor; Bronisz, Robert; Giuliano, B. M.; Fausto, Rui; Wierzejewska, Maria

doi:10.1021/jp202925r

Cited by 24 publications

(17 citation statements)

References 61 publications

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“…52 This has been confirmed by many experimental observations. 13,29 Therefore, a detailed structural theoretical characterization has been carried out in this study for both 1H-and 2Htautomers of TAA. As it is shown below, for this molecule both tautomers were indeed experimentally observed in this work.…”

Section: Potential Energy Surface Of Taamentioning

confidence: 99%

“…Tautomerism has been extensively studied in a great variety of azoles [5][6][7][8] as well as in other similar systems, including tetrazoles. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] In these studies, the preference for a specific a) Author to whom correspondence should be addressed. Electronic mail: reva@qui.uc.pt tautomer or tautomers at different proportions, according to the physical state of the compound, has been established.…”

Section: Introductionmentioning

confidence: 99%

“…The energy barriers to tautomerization through a double proton transfer are generally lower than those for unimolecular tautomerization (i.e., values below 50 kJ mol −1 for assisted tautomerization vs. values above 150 kJ mol −1 for unimolecular tautomerization). 13,14,36 The subject of this study, (tetrazol-5-yl)-acetic acid (TAA), is an interesting molecule from both theoretical and experimental points of view. On one hand, it may exhibit tautomerism associated with the position of the annular hydrogen atom.…”

Section: Introductionmentioning

confidence: 99%

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Tetrazole acetic acid: Tautomers, conformers, and isomerization

Araujo-Andrade

Reva

Fausto

2014

The Journal of Chemical Physics

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Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol(-1) energy range and should be appreciably populated at the sublimation temperature (∼330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol(-1)) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol(-1)). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm(-1), where the first OH stretching overtone vibrations of 1ccc and 2pcc occur. The reverse transformations could be induced by irradiations at 7010 and 7030 cm(-1), transforming 1cct and 2pct back to 1ccc and 2pcc, also selectively. Besides the NIR-induced transformations, the photogenerated 1cct and 2pct forms also decay in N2 matrices back to 1ccc and 2pcc spontaneously, with characteristic decay times of hours (1H) and tens of minutes (2H). The decay mechanism is rationalized in terms of the proton tunneling. In crystals, TAA exists exclusively as 1H-tautomer. By contrast, the tautomeric composition of the matrix-isolated monomers was found to consist of both 1H- and 2H-tautomers, in comparable amounts. A mechanistic discussion of the tautomerization process occurring during sublimation, accounting also for the observed minor decomposition of TAA leading to CO2 and 5-methyl-tetrazole, is proposed.

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Section: Potential Energy Surface Of Taamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tetrazole acetic acid: Tautomers, conformers, and isomerization

Araujo-Andrade

Reva

Fausto

2014

The Journal of Chemical Physics

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“…Although the photochemistry of tetrazole derivatives has been the subject of a number of studies, the photolysis of triazoles was rarely investigated until now. − In the unsubstituted triazole molecule, N 2 or HCN elimination is the main pathway of UV photolysis leading to formation of such products as hydrogen cyanide N -methylide, or cyanamide, carbodiimide, and nitrilimine …”

Section: Introductionmentioning

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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“…Such tautomerism involves the hydrogen migration between different nitrogen atoms within the ring. Knowledge of the tautomeric preferences in organic molecules, especially in tetrazoles and triazoles, is of importance since their functionality or physicochemical activity may be tautomer sensitive [14][15][16][17]. A number of papers have been published concerning different triazole tautomers, solvent effects on the equilibria between them [18][19][20][21] as well as the proton transfer phenomena in azole-based coordination polymers [22].…”

Section: Introductionmentioning

confidence: 99%