Electronic stark effect studies of a porphyrin-based push-pull chromophore displaying a large first hyperpolarizability: State-specific contributions to β

Journal of the American Chemical Society

Volumn 120, Issue 11, 1998, Pages 2606-2611

  Karki, Laba ^a   Vance, Fredrick W ^a   Hupp, Joseph T ^a   LeCours, Steven M ^b   Therien, Michael J ^b  

^a NORTHWESTERN UNIVERSITY   (United States)

^b UNIVERSITY OF PENNSYLVANIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

COPPER COMPLEX; PORPHYRIN; ZINC COMPLEX;

ABSORPTION SPECTROSCOPY; ARTICLE; DIPOLE; HYPERPOLARIZATION; LIGHT SCATTERING;

EID: 0032565135     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja973593v     Document Type: Article

References (33)

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3. -30 esu (Marder, S. R.; Cheng, L.-T.; Tiemann, B. G.; Friedli, A. C.; Blanchard-Desce, M.; Perry, J. W.; Skinhøj, J. Science 1994, 263, 511).
4. -30 esu (Marder, S. R.; Cheng, L.-T.; Tiemann, B. G.; Friedli, A. C.; Blanchard-Desce, M.; Perry, J. W.; Skinhøj, J. Science 1994, 263, 511).
5. -30 esu (Marder, S. R.; Cheng, L.-T.; Tiemann, B. G.; Friedli, A. C.; Blanchard-Desce, M.; Perry, J. W.; Skinhøj, J. Science 1994, 263, 511).
6. Priyadarshy, S.; Therien, M. J.; Beratan, D. N. J. Am. Chem. Soc. 1996, 118, 1504.
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10. The internal field is the product of the externally applied local field correction factor. For a spherical cavity model, the correction factor (assuming a solvent continuum) is 3∈/(2∈ + 1). The experimentally determined value of ∈ for 2-methyltetrahydrofuran glass is 4.0, which yields an estimated correction factor of 1.28.
11. (a) Boxer, S. G. In The Photosynthetic Reaction Center; Academic Press: New York, 1993; Vol. II, pp 179-220.
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15. χ values as large as 38° can be generated (Oh, Ph.D. Thesis, Department of Chemistry, Stanford University, 1991). In principle, this alternative explanation could be evaluated by obtaining higher resolution Stark and linear absorption spectra, presumably at liquid helium temperature where inhomogeneous broadening is less significant.
16. 3, where the positive sign indicates that the excited state in each instance is more polarizable than the ground state. Large positive polarizability changes are generally indicative of significant excited-state interactions with multiple higher lying states.
17. -1) (Creutz, C.; Newton, M. D.; Sutin, N. J. Photochem. Photobiol. A: Chem. 1994, 82, 47).
18. 4
19. 12 of comparable magnitude to those listed in Table 1.
20. LeCours, S. M.; Philips, C. M.; de Paula, J. C.; Therien, M. J. J. Am. Chem. Soc. 1997, 119, 12578-12589.
21. The Q and B bands were each fit to eq 1 by using three parameters (i.e. the overall band in each region was treated as a single electronic transition). Due to the narrowness of the B band linear absorption and the relatively large spectral band-pass employed in the electroabsorption experiment, signals for the latter may be artificially broadened. In any case, the apparent changes in polarizability upon excitation of 2 are qualitatively similar to those reported by Davidsson (Chem. Phys. 1980, 45, 409-414) for free base tetraphenylporphyrin.
22. x is likely to contribute to the first derivative signal since the associated changes in dipole moment are vanishingly small (see ref 10).
23. (a) Kanis, D. R.; Ratner, M. A.; Marks, T. J. Chem. Rev. 1994, 94, 195.
24. (b) Kanis, D. R.; Lacroix, G. P.; Ratner, M. A.; Marks, T. J. J. Am. Chem. Soc. 1994, 116, 10089.
25. (c) Kanis, D. R.; Marks, T. J.; Ratner, M. A. Nonlinear Opt. 1994, 6, 317.
26. Recall that the term "two-level" refers to each contribution to the sum-over-states expression (i.e., the ground level and one other level). The summation is then carried out over all available states (in this case seven observed excited states).
27. (a) Oudar, J. L.; Chemla, D. S. J. Chem. Phys. 1977, 66, 2664.
28. (b) Oudar, J. L. J. Chem. Phys. 1977, 67, 446.
29. (c) Willens, A.; Rice, J. E.; Burland, D. M.; Shelton, D. P. J. Chem. Phys. 1992, 97, 7590.
30. It should be noted that eqs 2 and 3 were derived for multiple electronic excited states. In the absence of appropriate theory, we have used eqs 2 and 3 to account also for multiple vibronic excited state contributions. We recognize that for hyper-Rayleigh scattering under resonant conditions, the approach almost certainly is not fully correct. (For example, it would predict significant destructive vibronic interference effects that have not been observed in excitation profile studies.) We suggest that under pre-and/or post-resonant conditions, however, eq 3 should prove semiquantitatively applicable to studies entailing sums over vibronic states.
31. 30 esu (see ref 2).
32. -1 (1064 nm) excitation. Unfortunately, we lack the necessary experimental excited-state to excited-state transition dipole moment information to make quantitative predictions.
33. We have assumed, for simplicity, that dipole moment changes and oscillator strengths for 3 are the same as those measured for 1.