Matrix induced localization of proton tunneling in malonaldehyde

Firth, D. W.; Barbara, Paul F.; Trommsdorff, H.P.

doi:10.1016/0301-0104(89)80058-8

Cited by 88 publications

(57 citation statements)

References 28 publications

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“…No evidence for proton tunnelling is found, similarly to what is observed for molecules isolated in argon matrices [42,53], probably due to a dynamical damping of the proton movement through the matrix phonons. To our knowledge, among similar molecules having an H position in a symmetric double well-potential between O atoms, this proton transfer in the ground electronic state has been observed in the case of matrix isolation only for tropolone [57] and only for the two modes the most involved in this proton transfer, i.e., the stretchings of the OH-bond and of the H-bond.…”

Section: Discussionsupporting

confidence: 47%

“…Figure 4,a shows the spectrum obtained after deposition: no band is present in this n OH region, as expected due to the large red-shift [37,38] of this mode. In addition, the broadening of this vibration is large for the isolated molecule and is expected to be even larger for the molecule in a solidstate medium: this mode is therefore not observed for the molecule isolated in matrices [53,54]. According to our PED analysis, the two broad and structured bands at 1652 cm -1 (FWHM:~7 cm -1 for the main the two sets of calculated frequencies (Fig.…”

Section: Methodsmentioning

confidence: 99%

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Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Trivella¹,

Coussan²,

Chiavassa³

et al. 2006

Low Temperature Physics

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Structure and reactivity of the eight enolic forms (one chelated and seven non-chelated) of malonaldehyde and acetylacetone are compared through theoretical and experimental data. Ground-state geometries, energies, and vibrational frequencies are calculated with the B3LYP/6-311++G(2d,2p) model chemistry. The electronic delocalisation as well as the cis/trans rotamer properties are analysed. The hydrogen bond strength of the chelated forms can be estimated by the energy difference between chelated and non-chelated forms, and its enhancement due to methyl-induced electron release is estimated at 1.7 kcal·mol -1 . UV-and IR-induced reactivity of molecules isolated in nitrogen matrices is studied by means of FT-IR spectrometry. Interconversion between rotamers is the main process observed for both molecules, only some among the seven non-chelated forms being created.PACS: 36.20.Ng, 31.15.Ar

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Section: Discussionsupporting

confidence: 47%

Section: Methodsmentioning

confidence: 99%

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Trivella¹,

Coussan²,

Chiavassa³

et al. 2006

Low Temperature Physics

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“…Low temperature measurements of the spectra of MA isolated in rare gas matrices have also been carried out and compared to ab initio calculations at the MP2/DZP level. 18,19 A recent experiment with high spectral resolution has provided more details about the couplings of the C v O stretch with rotations. 20 From a theoretical perspective, it is quite challenging to assign the spectrum of a fairly strong hydrogen bond due to the substantial coupling between the hydrogen motion and other degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

A generalized reactive force field for nonlinear hydrogen bonds: Hydrogen dynamics and transfer in malonaldehyde

Yang

Meuwly

2010

The Journal of Chemical Physics

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Using molecular dynamics ͑MD͒ simulations, the spectroscopy and dynamics of malonaldehyde is investigated. To this end, the recently proposed molecular mechanics with proton transfer ͑MMPT͒ potential is generalized to nonlinear hydrogen bonds. The calculated properties for malonaldehyde in both gas and condensed phases, including equilibrium geometries, infrared spectra, tunneling splittings, and hydrogen transfer rates, compare well with previous experimental and computational works. In particular, by using a harmonic bath averaged ͑HBA͒ Hamiltonian, which is based on a reaction path Hamiltonian, it is possible to estimate the tunneling splitting in an efficient manner. It is found that a zero point corrected barrier of 6.7 kcal/mol and effective masses of 1.234 ͑i.e., 23.4% larger than the mass of a physical H-atom͒ and 1.117 ͑for the physical D-atom͒ are consistent with the measured splittings of 21.6 and 2.9 cm −1 , respectively. The HBA Hamiltonian also yields a pair of hydrogen transfer fundamentals at 1573 and 1267 cm −1 , similar to results obtained with a reaction surface Hamiltonian on a MP2/6-31G ‫ءء‬ potential energy surface. This amounts to a substantial redshift of more than 1000 cm −1 which can be rationalized by comparison with weakly ͑HCO + : rare gas͒ and strongly ͑H 2 O u H + u OH 2 ͒ proton-bound systems. Hydrogen transfer rates in vacuum and water were determined from the validated MMPT potential and it is found that the solvent enhances the rate by a factor of 5 at 300 K. The rates of 2.4/ns and 10/ns are commensurate with previous density functional tight binding ab initio MD studies.

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“…Peaks #20 and #26 were assigned as representing the m 15 (nominal O_O stretch) and m 21 (out-ofplane skeletal deformation) fundamentals, respectively [15,59,60], with no specific tunneling doublet or hot band assignments made. No evidence for the presence of resolved spectral tunneling doublets was reported by Firth et al [17] for Ar-isolated MA or by Chiavassa et al [18] Figure 1.2 Infrared spectrum of MA(OH) in the 200-300 cm -1 region due to Smith et al [15]. Spectral doublet separations DS 21 and DS 15 replace the single-peak assignments m 15 = peak 20 and m 21 = peak 26. in Ar, Kr, and Xe matrices.…”

Section: Coherent Tunneling Splitting Phenomena In Malonaldehydementioning

confidence: 91%

“…MA has 21 and TRN has 39 internal coordinates available for coupling into their tunneling processes. MA, with a developing experimental base [9][10][11][12][13][14][15][16][17][18][19][20][21], holds a computational edge over TRN which currently stands alone in its size group for its catalog of spectroscopic tunneling structures [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. With 15 atoms TRN is reasonably expected to model elements of the intramolecular dynamical behavior occurring in much larger molecules, and it is amenable to high level experimental and theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Coherent Proton Tunneling in Hydrogen Bonds of Isolated Molecules: Malonaldehyde and Tropolone

Redington

2006

Hydrogen‐Transfer Reactions

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A series of articles reporting temperature dependent H and D isotope effects on the rates of certain enzymatic H transfer reactions show there is quantum tunneling by the H in these systems [1][2][3][4][5][6][7]. Theoretical considerations [4,6,7] infer vibrations within the enzyme-substrate complex, especially within the enzyme protein, develop transient geometrical configurations fomenting the tunneling process. Details of the promoting vibrations are still speculative, but it seems clear they work through transient reshaping of the potential energy surface (PES) barrier region, its width, energy maximum, overall contour, to provide "gated" impetus to H tunneling and to product escape.Molecules hosting coherent H tunneling activity in the presence of complex vibrational structure are of immediate interest in the above context. They provide sharp data points probing specific vibrational couplings along the large amplitude tunneling coordinate, and they probe portions of the PES topography in detail. Studies on isotopomers and close chemical congeners provide clusters of data points reflecting systematic changes of the dynamical behavior. In this chapter research on the coherent tunneling properties of malonaldehyde, tropolone, and tropolone derivatives is surveyed. These are among the few currently known 10-15 atom molecules showing clear-cut spectral doublet structures signifying coherent tunneling properties. Interestingly, the equal double-minimum global PESs for these molecules, notably for S 0 tropolone, are also poised for demonstrations of tunneling activity by the heavy atoms. The presence of H tunneling in some enzymatic systems is newly recognized; tunneling processes by heavy atoms such as C, N, and O may also prove consequential. Zuev et al. [8] recently published low temperature rate data and theoretical-computational results showing the tunneling of C atom from a single quantum state during the ring expansion isomerization of 1-methycyclobutylfluorocarbene.

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Matrix induced localization of proton tunneling in malonaldehyde

Cited by 88 publications

References 28 publications

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

A generalized reactive force field for nonlinear hydrogen bonds: Hydrogen dynamics and transfer in malonaldehyde

Coherent Proton Tunneling in Hydrogen Bonds of Isolated Molecules: Malonaldehyde and Tropolone

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