Mechanism of trans-Azobenzene Izomerization: Role of the Rydberg 3s-Orbital of the Azo-Group and Phenylaminyl-Type Cations
Yu. A. Mikheev
Российский журнал физической химии А
https://doi.org/10.1134/S0036024421110157
An analysis is performed of data on the trans → cis-photoisomerization of azobenzene (trans-AB) in light of the Rydberg 3s orbital (R3s) of the azo-group induces the formation of electronically (e-) polarized tautomers (Z+) in addition to its electrically neutral tautomer (Z). The Z+ tautomers have a chromogenic center in the form of a phenylaminyl type cation (PhAT) with a Vis excitation band at λm = 445–450 nm. It is found that the isomerization of trans-AB under the action of Vis light and UV radiation proceeds through the photoexcited polarized e-tautomer Z+*, which undergoes adiabatic changes in its e-configurations under the influence of the R3s-orbital. The Z+* state (with one PhAT cation) then transitions to the Z++* state (with two PhAT cations), which participates in competitive transformations: isomerization in cis-AB and a return to Z+*, which relaxes in Z+. It is shown that a rotational isomerization pathway can form when there are no steric obstacles blocking rotation around the N–N bond. When there are such obstacles, isomerization proceeds through adiabatic displacement of the ph-rings in intermediate Z++*, first into its rectilinear conformation, and then toward one another through the stage of intermediate e-polarized excited state cis-AB*, which has a three-electron bond in addition to the σ-bond of the azo-group between adjacent sp2 orbitals.
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334, Moscow, RussiaYu. A. Mikheev
- A. N. Terenin, Photonics of Molecules of Dyes and Related Organic Compounds (Nauka, Leningrad, 1967).
- P. F. Gordon and P. Gregory, Organic Chemistry in Colour (Springer, Berlin, 1983).
- M. Bockmann, N. L. Doltsinis, and M. Dominik, J. Phys. Chem. A 114, 745 (2010).
- M. Pederzoli, J. Pittner, M. Barbatti, and H. Lischka, J. Phys. Chem. A 115, 11136 (2011).
- Yu. Harabuchi, M. Ishii, A. Nakayama, et al., J. Chem. Phys. 138, 064305 (2013).
- A. J. Neukirch, L. C. Shamberger, E. Abad, et al., J. Chem. Theory Comput. 10, 14 (2014).
- J. M. Robertson, J. Chem. Soc., 232 (1939).
- G. C. Hampson and J. M. Robertson, J. Chem. Soc., 409 (1941).
- M. Kasha, Disc. Faraday Soc., No. 9, 14 (1950).
- F. Halverson and R. C. Hirt, J. Chem. Phys. 19, 711 (1951).
- G. J. Brealey and M. Kasha, J. Am. Chem. Soc. 77, 4462 (1955).
- P. P. Birnbaum, J. H. Linford, and D. W. G. Style, Trans. Faraday Soc. 50, 735 (1954).
- P. P. Birnbaum and D. W. G. Style, Trans. Faraday Soc. 50, 1192 (1954).
- J. W. Sidman, J. Chem. Rev. 58, 689 (1958).
- H. H. Jaffe, Yeh Si-Jung, and R. Gardner, J. Mol. Spectrosc. 2, 120 (1958).
- Yu. A. Mikheev, L. N. Guseva, and Yu. A. Ershov, Russ. J. Phys. Chem. A 89, 2036 (2015).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 92, 1499 (2018).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 92, 1911 (2018).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 93, 369 (2019).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 93, 1411 (2019).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 94, 196 (2020).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 94, 1716 (2020).
- Yu. A. Mikheev and Yu. A. Ershov, Russ. J. Phys. Chem. A 94, 2360 (2020).
- N. J. Turro, Molecular Photochemistry (Benjamin, New York, 1965).
- S. F. Mason, J. Chem. Soc., 1240 (1959).
- Yu. A. Mikheev, L. N. Guseva, and Yu. A. Ershov, Russ. J. Phys. Chem. A 89, 224 (2015).
- B. Robin and W. T. Simpson, J. Chem. Phys. 36, 580 (1962).
- G. A. Coulson, Valence (Oxford Univ., London, 1961).
- D. L. Beveridge and H. H. Jaffe, J. Am. Chem. Soc. 88, 948 (1966).
- J. Calvert and J. Pitts, Photochemistry (Wiley, New York, 1967).
- K. Higashi, H. Baba, and A. Rembaum, Quantum Organic Chemistry (Interscience, New York, 1965).
- P. Bortolus and S. Monti, J. Phys. Chem. 83, 648 (1979).
- H. Rau and E. Luddecke, J. Am. Chem. Soc. 104, 1616 (1982).
- H. Rau, J. Photochem. 26, 221 (1984).
- T. Fujino and T. Tahara, J. Phys. Chem. A 140, 4203 (2000).
- S. Monti, G. Orlandi, and P. Palmieri, Chem. Phys. 71, 87 (1982).
- P. Cattaneo and M. Persiko, Phys. Chem. Chem. Phys. 1, 4739 (1999).
- I. K. Lednev, T.-Q. Ye, R. E. Hestler, and J. N. Moore, J. Phys. Chem. 100, 13338 (1996).
- I. K. Lednev, N.-Q. Ye, P. Matousek, et al., Chem. Phys. Lett., No. 290, 68 (1998).
- A. Streitwieser, Jr., Molecular Orbital Theory for Organic Chemists (Wiley, New York, 1961).
- Ch.-W. Chang, Y.-Ch. Lu, Ts.-Te. Wang, and W.‑G. Diau, J. Am. Chem. Soc. 126, 10109 (2004).
- T. Fujino, S. Yu. Arzhantzev, and T. Tahara, J. Phys. Chem. A 105, 8123 (2001).
- I. K. Lednev, T.-Q. Ye, L. C. Abbot, et al., J. Phys. Chem. A 102, 9161 (1998).
- Ch. M. Stuart, R. R. Frontiera, and R. A. Mathies, J. Phys. Chem. A 111, 12072 (2007).
- M. Ya. Mel’nikov and V. A. Smirnov, Photochemistry of Organic Radicals (Mosk. Gos. Univ., Moscow, 1994), p. 69 [in Russian].
- D. P. Hoffman, S. R. Ellis, and R. A. Mathies, J. Phys. Chem. A 117, 11472 (2013).