Journal of Chemical Physics
Feedback | Help | Exit
The Journal of Chemical Physics
   
 
 
 
Previous Article
Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water
A combined experimental and theoretical study of the ultraviolet photolysis of CH2I2 in water is reported. Ultraviolet photolysis of low concentrations of CH2I2 in water was experimentally observed to...
Next Article
Microwave and ab initio studies of rare gas–methane van der Waals complexes
Rotational spectra of the weakly bound Kr–methane van der Waals complex were recorded using a pulsed molecular beam Fourier transform microwave spectrometer in the range from 3.5 to 18 GHz. Spect...

Infrared-induced conformational isomerization and vibrational relaxation dynamics in melatonin and 5-methoxy-N-acetyl tryptophan methyl amide

J. Chem. Phys. 120, 9033 (2004); doi:10.1063/1.1697389

Issue Date: 15 May 2004

You are not logged in to this journal. Log in

Brian C. Dian, Gina M. Florio, Jasper R. Clarkson, Asier Longarte, and Timothy S. Zwier
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084
The conformational isomerization dynamics of melatonin and 5-methoxy N-acetyltryptophan methyl amide (5-methoxy NATMA) have been studied using the methods of IR-UV hole-filling spectroscopy and IR-induced population transfer spectroscopy. Using these techniques, single conformers of melatonin were excited via a well-defined NH stretch fundamental with an IR pump laser. This excess energy was used to drive conformational isomerization. By carrying out the infrared excitation early in a supersonic expansion, the excited molecules were re-cooled into their zero-point levels, partially re-filling the hole created in the ground state population of the excited conformer, and creating gains in population of the other conformers. These changes in population were detected using laser-induced fluorescence downstream in the expansion via an UV probe laser. The isomerization quantum yields for melatonin show some conformation specificity but no hint of vibrational mode specificity. In 5-methoxy NATMA, no isomerization was observed out of the single conformational well populated in the expansion in the absence of the infrared excitation. In order to study the dependence of the isomerization on the cooling rate, the experimental arrangement was modified so that faster cooling conditions could be studied. In this arrangement, the pump and probe lasers were overlapped in space in the high density region of the expansion, and the time dependence of the zero-point level populations of the conformers was probed following selective excitation of a single conformation. The analysis needed to extract isomerization quantum yields from the timing scans was developed and applied to the melatonin timing scans. Comparison between the frequency and time domain isomerization quantum yields under identical experimental conditions produced similar results. Under fast cooling conditions, the product quantum yields were shifted from their values under standard conditions. The results for melatonin are compared with those for N-acetyl tryptophan methyl amide. ©2004 American Institute of Physics.
History: Received 19 September 2003; accepted 17 February 2004
Permalink: http://link.aip.org/link/?JCPSA6/120/9033/1
BUY THIS ARTICLE   (US$28)
Download HTML Download Sectioned HTML Download PDF (576 kB) View Cart

KEYWORDS and PACS

Keywords
PACS
  • 82.30.Qt
    Isomerization and rearrangement in chemical reactions
  • 36.20.Ey
    Macromolecular conformation (statistics and dynamics)
  • 36.20.Kd
    Electronic structure and spectra of macromolecules
  • 87.15.He
    Biomolecular dynamics and conformational changes
  • 87.15.Mi
    Spectra, photodissociation, and photoionization of biomolecules; bioluminescence
  • 33.15.Mt
    Molecular rotation, vibration, and vibration-rotation constants
  • 33.20.Tp
    Vibrational analysis (molecular spectra)
  • 33.15.Bh
    General molecular conformation and symmetry; stereochemistry
  • 33.20.Ea
    Infrared molecular spectra
  • 33.20.Lg
    Ultraviolet molecular spectra
  • 33.80.Be
    Molecular level crossing and optical pumping
  • 33.50.Dq
    Molecular fluorescence and phosphorescence spectra
  • YEAR: 2004

RELATED DATABASES


To view database links for this article,
you need to log in.
To view database links for this article,
you need to log in.

PUBLICATION DATA

ISSN:
0021-9606 (print)   1089-7690 (online)
Publisher:
AIP is a member of CrossRef AIP

REFERENCES (33)
View in Separate Window/Tab
For access to fully linked references, you need to log in. For access to fully linked references, you need to Log in.
  1. J. R. Carney and T. S. Zwier, J. Phys. Chem. A 104, 8677 (2000).
  2. E. G. Robertson and J. P. Simons, PCCP 3, 1 (2001).
  3. T. S. Zwier, J. Phys. Chem. A 105, 8827 (2001).
  4. J. R. Carney and T. S. Zwier, Chem. Phys. Lett. 341, 77 (2001).
  5. B. C. Dian, A. Longarte, S. Mercier, D. Evans, D. J. Wales, and T. S. Zwier, J. Chem. Phys. 117, 10688 (2002).
  6. G. M. Florio, R. Christie, K. D. Jordan, and T. S. Zwier, J. Am. Chem. Soc. 124, 10236 (2002).
  7. B. C. Dian, A. Longarte, P. R. Winter, and T. S. Zwier, J. Chem. Phys. 120, 133 (2004).
  8. M. Gerhards and C. Unterberg, PCCP 4, 1760 (2002).
  9. M. Gerhards, C. Unterberg, and A. Gerlach, PCCP 4, 5563 (2002).
  10. E. Nir, C. Janzen, P. Imhof, K. Kleinermanns, and M. S. d. Vries, PCCP 4, 740 (2002).
  11. C. Plutzer, I. Hunig, K. Kleinermanns, E. Nir, and M. S. d. Vries, Phys. Chem. Chem. Phys. 4, 838 (2003).
  12. C. Unterberg, A. Gerlach, T. Schrader, and M. Gerhards, J. Chem. Phys. 118, 8296 (2003).
  13. J. B. Fenn, Annu. Rev. Phys. Chem. 47, 1 (1996).
  14. T. Ebata, K. Kouyama, and N. Mikami, J. Chem. Phys. 119, 2947 (2003).
  15. B. C. Dian, A. Longarte, and T. S. Zwier, Science 296, 2369 (2002).
  16. G. W. Flynn, C. S. Parmenter, and A. M. Wodtke, J. Phys. Chem. 100, 12817 (1996).
  17. R. A. Coveleskie, D. A. Dolton, and C. S. Parmenter, J. Phys. Chem. 89, 645 (1985).
  18. R. A. Colveleskie, D. A. Dolton, and C. S. Parmenter, J. Phys. Chem. 89, 655 (1985).
  19. K. W. Holtzclaw and C. S. Parmenter, J. Chem. Phys. 84, 1099 (1986).
  20. D. A. Dolson, K. W. Holtzclaw, D. B. Moss, and C. S. Parmenter, J. Chem. Phys. 84, 1119 (1986).
  21. D. A. Evans, D. J. Wales, B. C. Dian, and T. S. Zwier, J. Chem. Phys. 120, 148 (2004).
  22. A. D. Becke, J. Chem. Phys. 98, 5648 (1993).
  23. M. J. Frisch, J. A. Pople, and J. S. Binkley, J. Chem. Phys. 80, 3265 (1984).
  24. M. J. T. Frisch, G. W. Schlegel, H. B. Scuseria et al., GAUSSIAN 98, Revision A.11.3, Gaussian, Inc., Pittsburgh, PA (1998).
  25. C. W. Garland, J. W. Nibler, and D. P. Shoemaker, in Experiments in Physical Chemistry (McGraw–Hill, New York, 2003), 733 pp.
  26. D. M. Lubman, C. T. Rettner, and R. N. Zare, J. Phys. Chem. 86, 1129 (1982).
  27. C. Schiene-Fischer and G. Fischer, J. Am. Chem. Soc. 123, 6227 (2001).
  28. G. Scherer, M. L. Kramer, M. Schutkowski, U. Reimer, and G. Fischer, J. Am. Chem. Soc. 120, 5568 (1998).
  29. P. Li, X. G. Chen, E. Shulin, and S. A. Asher, J. Am. Chem. Soc. 119, 1116 (1997).
  30. O. M. Becker and M. Karplus, J. Chem. Phys. 106, 1495 (1997).
  31. D. J. Wales, J. P. K. Doye, M. A. Miller, P. N. Mortenson, and T. R. Walsh, in Advances in Chemical Physics, edited by I. P. a. S. A. Rice (Wiley, New York, 2000), Vol. 115, p. 1.
  32. J. R. Barker, J. Phys. Chem. 88, 11 (1984).
  33. M. Damm, F. Deckert, H. Hippler, and J. Troe, J. Phys. Chem. 95, 2005 (1991).

CITING ARTICLES
For access to citing articles, you need to log in.
For access to citing articles, you need to Log in.


Copyright © American Institute of Physics