Effect of deuteration on the fluorescence excitation spectrum of tropolone: a theoretical study

Paz, Juan J.; Moreno, Miquel; Lluch, José M.

doi:10.1016/s0301-0104(99)00148-2

Cited by 2 publications

(2 citation statements)

References 41 publications

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“…Interestingly, in the systems investigated thus far that exhibit tunneling splitting due to proton transfer, the barrier was lower in the excited state. Such was the case of tropolone, − its derivatives, ,,− and hydroxyphenalenones. ,, …”

Section: Discussionmentioning

confidence: 99%

Evidence for Two Forms, Double Hydrogen Tunneling, and Proximity of Excited States in Bridge-Substituted Porphycenes: Supersonic Jet Studies

et al. 2006

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Laser-induced fluorescence and dispersed fluorescence spectra measured in supersonic jets for 9,10,19,20-tetra-n-methylporphycene and 9,10,19,20-tetra-n-propylporphycene reveal, for both compounds, the presence of two different species which are assigned to trans and cis tautomeric forms. Doublet splitting of lines is observed, disappearing upon deuteration of the inner nitrogen atoms. This finding is interpreted as an indication of double hydrogen tunneling. The values of tunneling splitting are obtained for both ground and lowest singlet excited states. The splitting is similar for cis and trans forms, and the barrier for tautomerization is larger in the excited state. Due to the coupling of hydrogen motion with rotation of alkyl substituents, tautomerization occurs in an asymmetric double minimum potential, with the ordering of energy minima reversed upon excitation. The second singlet excited state is found to lie very close to S(1), thus facilitating an efficient radiationless depopulation.

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Section: Discussionmentioning

confidence: 99%

Evidence for Two Forms, Double Hydrogen Tunneling, and Proximity of Excited States in Bridge-Substituted Porphycenes: Supersonic Jet Studies

et al. 2006

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“…Observations for the ZP, out-of-plane deformation, and nominal O_O stretching spectral doublets are shown in Table 1.4 [48]. The less pronounced consequences on the effective PESs, vibrational spectral doublets, and symmetries arising through the deuteration of the 3-, 4-, and 5-positions have been presented [41,96].…”

Section: Discussionmentioning

confidence: 97%

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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Effect of deuteration on the fluorescence excitation spectrum of tropolone: a theoretical study

Cited by 2 publications

References 41 publications

Evidence for Two Forms, Double Hydrogen Tunneling, and Proximity of Excited States in Bridge-Substituted Porphycenes: Supersonic Jet Studies

Evidence for Two Forms, Double Hydrogen Tunneling, and Proximity of Excited States in Bridge-Substituted Porphycenes: Supersonic Jet Studies

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

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