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Journal of Chemical Physics / Volume 135 / Issue 24 / COMMUNICATIONS
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J. Chem. Phys. 135, 241101 (2011); http://dx.doi.org/10.1063/1.3672101 (4 pages)

Communication: Manipulating the singlet-triplet equilibrium in organic biradical materials

Ö. Günaydın-Şen1, J. Fosso-Tande1, P. Chen1, J. L. White1, T. L. Allen2, J. Cherian3, T. Tokumoto3, P. M. Lahti2, S. McGill3, R. J. Harrison1,4, and J. L. Musfeldt1

1Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
2Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
3National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
4Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

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(Received 6 September 2011; accepted 30 November 2011; published online 27 December 2011)

We investigated the tunability of the singlet-triplet equilibrium population in the organic biradical 1,4-phenylenedinitrene via magneto-optical spectroscopy. A rich magnetochromic response occurs because applied field increases the concentration of the triplet state species, which has a unique optical signature by comparison with the singlet biradical and the precursor molecule. A Curie-like analysis of the magneto-optical properties allows us to extract the spin gap, which is smaller than previously supposed. These measurements establish the value of local-probe photophysical techniques for magnetic property determination in open-shell systems such as biradicals where a traditional electron paramagnetic resonance Curie law analysis has intrinsic limitations.

© 2011 American Institute of Physics

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KEYWORDS and PACS

Keywords

configuration interactions, density functional theory, excited states, magneto-optical effects, molecule-photon collisions, organic compounds, photolysis

PACS

  • 82.50.Hp

    Processes caused by visible and UV light

  • 33.80.Eh

    Autoionization, photoionization, and photodetachment

  • 33.57.+c

    Magneto-optical and electro-optical spectra and effects

  • 31.15.vj

    Electron correlation calculations for atoms and ions: excited states

  • 31.15.vq

    Electron correlation calculations for polyatomic molecules

  • 31.15.ee

    Time-dependent density functional theory

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.3672101

PUBLICATION DATA

ISSN

0021-9606 (print)  
1089-7690 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

  1. C. Wentrup, Reactive Molecules: Neutral Reactive Intermediates in Organic Chemistry (Wiley, New York, 1984).
  2. Kinetics and Spectroscopy of Carbenes and Biradicals, edited by M. S. Platz (Plenum, New York, 1990).
  3. R. S. Sheridan, J. Phys. Org. Chem. 23, 326 (2010).
  4. H. Iwamura, Adv. Phys. Org. Chem. 26, 179 (1990).
  5. E. Leyva, M. S. Platz, G. Persy, and J. Wirz, J. Am. Chem. Soc. 108, 3783 (1986).
  6. N. P. Gritsan, Z. Zhu, C. M. Hadad, and M. S. Platz, J. Am. Chem. Soc. 121, 1202 (1999).
  7. J. Dobkowski, J. Michl, and J. Waluk, Phys. Chem. Chem. Phys. 5, 1027 (2003).
  8. M. Gisin, E. Rommel, J. Wirz et al., J. Am. Chem. Soc. 101, 2216 (1978).
  9. T. Harder, J. Bendig, G. Scholz, and R. Stösse, J. Am. Chem. Soc. 118, 2497 (1996).
  10. M. B. Taraban, A. I. Kruppa, O. S. Volkova et al., J. Phys. Chem. A 104, 1811 (2000).
  11. Z. Xu and B. Hu, Adv. Funct. Mater. 18, 2611 (2008).
  12. J.-W. Yoo, C.-Y. Chen, H. W. Jang et al., Nature Mater. 9, 638 (2010).
  13. M. Minato and P. Lahti, J. Am. Chem. Soc. 119, 2187 (1997).
  14. P. M. Lahti, A. S. Ichimura, and J. A. Sanborn, J. Phys. Chem. 105, 251 (2001).
  15. S. Nimura, O. Kikuchi, T. Ohana et al., Chem. Lett. 25, 125 (1996).
  16. Without thermal processes.
  17. R. A. Kendall, E. Aprà, D. E. Bernholdt et al., Comput. Phys. Commun. 128, 260 (2000).
  18. A. D. Becke, J. Chem. Phys. 98, 5648 (1993).
  19. R. J. Harrison, J. Chem. Phys. 94, 5021 (1991)JCPSA6000094000007005021000001. [ISI] [CAS]
  20. R. S. Berns, Principles of Color Technology (Wiley, New York, 2000).
  21. A. Reiser, G. Bowes, and R. J. Horne, Trans. Faraday Soc. 63, 3162 (1966).
  22. S. Leach, M. Vervloet, A. Desprès et al., Chem. Phys. 160, 451 (1992). [Inspec] [ISI] [CAS]
  23. The azide group rotates freely at room temperature and is locked in the plane of the ring at low temperature Ref. 21.
  24. A. Reiser, H. M. Wagner, R. Marley, and G. Bowes, Trans. Faraday Soc. 63, 2403 (1967).
  25. B. Bleaney and K. D. Bowers, Proc. R. Soc. London, Ser. A 214, 451 (1952).
  26. See supplementary material at http://dx.doi.org/10.1063/1.3672101 for a discussion of the vibronic coupling in this system. [EPAPS]
  27. Magnetism Fundamentals, E. du Trémolet de Lacheisserie, edited by D. Gignoux and M. Schlenker (Springer, Boston, 2005).
  28. J. A. Berson, Chemistry of Quinonoid Compounds, edited by S. Patai and Z. Rappoport (Wiley, New York, 1988),Vol. 2.
  29. Compare, for example, the different conclusions reached from EPR Curie law analysis by Dowd et al. vs. the magnetically determined results of Matsuda and Iwamura, viz.: (a) P. Dowd, W. Chang, and Y. H. Paik, J. Am. Chem. Soc. 109, 5284 (1987); [Inspec]
    (b)K. Matsuda and H. Iwamura, J. Chem. Soc. Perkin Trans. 2, 1023 (1998).
  30. Use of temperature to change the population involves vibrations whereas the field technique is rigid.
  31. This prediction for spin gap closure and ground state inversion can be tested with pulsed field magnetization.
  32. X. S. Xu, T. V. Brinzari, S. Lee, Y. H. Chu, L. W. Martin, A. Kumar, S. McGill, R. C. Rai, R. Ramesh, V. Gopalan, S. W. Cheong, and J. L. Musfeldt, Phys. Rev. B 79, 134425 (2009).

Figures (click on thumbnails to view enlargements)

FIG.1
Chemical structure of the 1,4-diazidobenzene precursor (blue), and the dinitrene biradical 1,4-phenylenedinitrene (red) after photochemical reaction. Temperature or applied magnetic field drives the singlet-triplet equilibrium.

FIG.1 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.2
Schematic view of how temperature and magnetic field act to populate the triplet state in the biradical.

FIG.2 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.3
TDDFT and selected CI spectra (square of the transition dipole, μ2, in atomic units) of 1,4-phenylenedinitrene. For clarity, dipole-allowed transitions are indicated in black. Dipole-forbidden transitions are indicated in red as negative –0.1, weak allowed transitions are increased to 0.1, and intense transitions truncated to 0.5. The most intense feature in the singlet CI spectrum at 251 nm (predominantly N → N* single excitation, with lesser π → π* single excitation) has μ2 = 12 and does not appear in the triplet spectrum that has its most intense feature with μ2 = 0.3 at 162 nm. The spurious low energy features in the singlet TDDFT spectrum are omitted. N and N* indicate the b2g and b3u orbitals, respectively.

FIG.3 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.4
Absorption spectra of pristine 1,4-diazidobenzene and the biradical photo-product 1,4-phenylenedinitrene at 5 K. Color-rendering calculations20 and photos are in good agreement. Left: Absolute value of the absorption difference, ∣Δα∣ = ∣α(T)−α(T = 5 K)∣, vs. wavelength for the unphotolyzed film at 300, 200, 100, 80, 60, 40, and 20 K. Right: Emission vs. wavelength for the photolyzed film from which the Stokes shift was extracted.

FIG.4 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

FIG.5
Absolute value of the absorption difference, ∣Δα∣ = ∣α(T) – α(T = 5 K)∣, vs. wavelength for the photolyzed biradical film at 80, 60, 40, and 20 K. Inset: Example Curie fit at 520 nm. These data allow a direct comparison of electron paramagnetic resonance and optical methods of spin gap determination. We find Δ0 = 230 ± 22 K, which compares well with that from electron spin resonance (288 K). A schematic view of the calculated triplet state excitations using the TDDFT method (shown at the bottom) in reasonable agreement with the |Δα| data in the main panel. The fine structure in the absorption difference spectrum is discussed in the supplementary material.26

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FIG.6
Absolute value of the absorption difference spectrum, ∣α(B) – α(0 T)∣, of the biradical photo-product vs. wavelength at 4.2 K, from which we extracted data for the Curie-like analysis. Data shown for B = 0, 5, 10, 15, 20, 25, 30, and 35 T. Inset: Example fit at 523 nm. These data allow us to probe the spin gap with field rather than with an analysis of relative thermal populations. We find Δ0 = 128 ± 18 K.

FIG.6 Download High Resolution Image (.zip file) | Export Figure to PowerPoint

Supplemental Files (EPAPS)


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