Abstract
Loop currents involve the circulation of electrons (or holes) around closed conjugated-bond loops. From the length of the orbital perimeter the kinetic energy per electron can be calculated. In chlorophyll a, four electronic excitations have been analyzed, including: (1) a single positive charge (hole) circling a 19-bond orbit with a Möbius twist (this is proposed as the effective ground state); (2) nine electrons, unevenly spaced, circling the same 19-bond orbit but without the Möbius twist (proposed as the red excited state); (3) nine electrons in the same orbit but evenly spaced and vibrationless (the hopping exciton); (4) ten electrons, unevenly spaced, in a 16-bond orbit (the blue excited state). The fit of theory to experiment is examined.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Platt, J. R. In: Radiation biology, ed. A. Hollaender, p. 71. New York: McGraw-Hill 1956
Kuhn, H.: J. Chem. Phys. 17, 1198 (1949)
Simpson, W. T.: J. Chem. Phys. 17, 1218 (1949)
Gouterman, M: J. Chem. Phys. 30, 1139 (1959)
Gouterman, M.: J. Chem. Phys. 33, 1523 (1960)
Weiss, C., Jr.: J. Mol. Spectroscopy 44, 37 (1972)
Christoffersen, R. E.: Int. J. Quant. Chem. XVI, 573 (1979)
Heilbronner, E.: Tetrahedron Letters 29, 1923 (1964)
Zimmerman, H. E.: Quantum mechanics for organic chemists. New York: Academic Press 1975
Rabinowitch, E. I.: Photosynthesis. New York: Interscience 1945
Fischer, H.: Naturwissenschaften 26, 401 (1940)
Geacintov, N. E., Van Nostrand, F., Pope, M., Tinkel, J. B.: Biochim. Biophys. Acta 226, 486 (1971)
Geacintov, N. E., Van Nostrand,F., Becker, J. F. In: Proc. 2nd Int. Congr. Photosyn. Res., ed. G. Forti, M. Arton, A. Melandri, vol. i, p. 283. The Hague: W. Junk 1972
Geacintov, N. E., Van Nostrand,F., Becker, J. F., Tinkel, J. B.: Biochim. Biophys. Acta 267, 65 (1972)
Breton, J., Michel-Villaz, M., Paillotin, G.: Biochim. Biophys. Acta 314, 42 (1973)
Breton, J., Mathis, P. In: Excited states of biological molecules, ed. J. B. Birks, p. 301. New York: John Wiley and Sons 1976
Emsley, J. W., Feeney, J., Sutcliffe, L. H.: High resolution nuclear magnetic resonance spectroscopy. Oxford: Pergamon Press 1965
Vysotsky, Y. B., Kuzmitsky, V. A., Solovyov, K. N.: Theoret. Chim. Acta (Berl.) 59, 467 (1981)
Maret, G., v. Schickfus, M, Mayer, A., Dransfeld, K.: Phys. Rev. Letters 35, 397 (1975)
Briat, B., Schooley, D. A., Records, R., Bunnenberg, E., Djerassi, C.: J. Am. Chem. Soc. 89, 6170 (1967).
Williams, W. P. In: Primary processes of photosynthesis, ed. J. Barber, p. 99. Amsterdam: Elsevier 1977
Murata, N., Nishimura, M., Takamiya, A.: Biochim. Biophys. Acta 126, 234 (1966)
Paschenko, V. Z., Protasov, S. V., Rubin, A. B., Timofeev, K. N., Zamazova, L. M., Rubin, L. B.: Biochim. Biophys. Acta 408, 143 (1975)
Bolton, J. R. In: Primary processes of photosynthesis, ed. J. Barber, p. 187. Amsterdam: Elsevier 1977
Clapp, R. E.: J. theor. Biol. 92, 15 (1981)
Christophorou, L. G., McCorkle, D. L., Carter, J. G.: J. Chem. Phys. 60, 3779 (1974)
Christophorou, L. G.: Atomic and molecular radiation physics. New York: Wiley-Interscience 1971
Seely, G. R. In: Primary processes of photosynthesis, ed. J. Barber, p. 1. Amsterdam: Elsevier 1977
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Clapp, R.E. Loop currents in chlorophyll a . Theoret. Chim. Acta 61, 105–133 (1982). https://doi.org/10.1007/BF00549138
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00549138