Changing pictures of molecular faces and depths of potential acting on an electron in molecule for intramolecular proton transfer reactions of formic acid and malonaldehyde

Zhao, Dong‐Xia; Zhao, Jian; Miao, Song; Zhu, Zunwei; Chen, Chengcheng; Yu-jing, Song

doi:10.1016/j.comptc.2017.05.035

Cited by 3 publications

(3 citation statements)

References 50 publications

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“…From the theoretical point of view, in the case of MA, namely, if numerous theoretical studies have been published on its ground state tunneling effect, − a lot fewer have addressed that of AA or MA and AA photochemistries. − Comparing those latter studies with our experimental results − we showed that AA electronic relaxation pathway proceeds through T 2 and T 1 states and that nonchelated forms are those which fragment. On the contrary, in MA case, electronic relaxation proceeds uniquely through singlet states and no fragmentation is observed.…”

Section: Introductionsupporting

confidence: 54%

“…MA and AA are known to exchange the enol proton in gas phase and in liquid, leading to a splitting of the ground state. 5,6,[19][20][21]35,36 It could be what happens here: we observe a kind of average situation in which proton is exchanged and concomitantly it remains enough forms of each CCC isomer to structure the band with this shoulder. It should also be noted that even this UV spectrum has been recorded in dichloroethane, at room temperature, the 269 nm band for CCC matches with those of MA and AA chelated forms, at 269−275 and 265−269 nm (recorded in cryogenic matrices), respectively.…”

Section: ■ Experimental Results and Discussionmentioning

confidence: 78%

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UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices

et al. 2020

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The broad band UV photochemistry of acetylacetaldehyde, the hybrid form between malonaldehyde and acetylacetone (the two other most simple molecules exhibiting an intramolecular proton transfer), trapped in four cryogenic matrices, neon, nitrogen, argon, and xenon, has been studied by IRTF spectroscopy. These experimental results have been supported by B3LYP/6-311G++(2d,2p) calculations in order to get S 0 minima together with their harmonic frequencies. On those minima, we have also calculated their vibrationally resolved UV absorption spectra at the time-dependent DFT ωB97XD/6-311+ +G(2d,2p) level. After deposition, only the two chelated forms are observed while they isomerize upon UV irradiation toward nonchelated species. From UV irradiation effects we have identified several nonchelated isomers, capable, in turn, of isomerizing and fragmenting, even if this last phenomenon seems to be most unlikely due to cryogenic cages confinement. On the basis of these findings, we have attempted a first approach to the reaction path of electronic relaxation. It appeared that, as with acetylacetone, the path of electronic relaxation seems to involve triplet states.Article pubs.acs.org/JPCA

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Section: Introductionsupporting

confidence: 54%

Section: ■ Experimental Results and Discussionmentioning

confidence: 78%

UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices

et al. 2020

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“…Maybe also for this reason, the majority of studies has so far been of theoretical nature. For example, if one searches in the Web Of Science database, three of the most recent articles are theoretical dealing with the intramolecular proton transfer. − The ground state tunneling splitting due to this proton transfer has been measured by Baughcum et al to be of ≈21 cm –1 with a tunneling period of ≈1.54 ps . We ourselves performed experiments in supersonic jets to elucidate the coupling between vibrational excitation and proton transfer motion, and we compared them to matrix experimental results, − concluding that in cryogenic matrices the proton transfer is totally quenched.…”

Section: Introductionmentioning

confidence: 99%

UV and IR Photochemistries of Malonaldehyde Trapped in Cryogenic Matrices

et al. 2018

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UV and IR photochemistries of malonaldehyde, the simplest molecule exhibiting an intramolecular proton exchange, have been studied in four cryogenic matrices at 4.3 K, N, Ne, Ar, and Xe. Samples have been irradiated using a UV and IR OPO type tunable laser, and with a broad band UV mercury lamp. UV and IR spectra have been recorded and compared with theoretical calculations carried out at the SAC-CI/6-31++G(d,p) (UV transitions) and B3LYP/6-311++G(2d,2p) (IR spectra) levels of theory. After deposition, the intramolecularly H-bonded form is found exclusively, while several open forms are formed upon UV irradiation. These open forms show ability to interconvert upon UV irradiation too. Some of them are also able to isomerize upon selective IR irradiations. The whole set of results allowed us to identify seven isomers among the eight postulated. The photodynamics of the electronic relaxation of malonaldehyde have also been investigated. By following the decay or rise of suited specific vibrational bands in the IR spectra, and by comparing the results with an earlier study of the homologous acetylacetone, we deduced that the electronic relaxation of malonaldehyde proceeds through singlet states, most probably through a 3-fold conical intersection, as postulated from theoretical calculations. In contrast with acetylacetone, malonaldehyde does not show fragmentation after UV excitation.

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Investigation of the hydrogen, halogen and pnicogen dimers by means of molecular face calculated by ab initio method

Zhao

Liu

et al. 2020

Theor Chem Acc

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Changing pictures of molecular faces and depths of potential acting on an electron in molecule for intramolecular proton transfer reactions of formic acid and malonaldehyde

Cited by 3 publications

References 50 publications

UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices

UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices

UV and IR Photochemistries of Malonaldehyde Trapped in Cryogenic Matrices

Investigation of the hydrogen, halogen and pnicogen dimers by means of molecular face calculated by ab initio method

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