SPECTRAL-LUMINESCENT CHARACTERISTICS OF NО2-SUBSTITUTED PORPHYRINS

UDC 535.34+535.35+535.372

Lazovskaya Olesya Ilgamovna – Lead Engineer, the Department of Biotechnology. Belarusian State Technological University (13a Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: lazovskaya@belstu.by

Vershilovskaya Irina Vatslavovna – PhD (Biology), Assistant Professor, the Department of Physics. Belarusian State Technological University (13a Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: vershilovskaya@belstu.by

Leontiev Viktor Nikolaevich – PhD (Chemistry), Associate Professor, Head of the Department of Biotechnology. Belarusian State Technological University (13a Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: leontiev@belstu.by

Ignatovets Olga Stepanovna – PhD (Biology), Associate Professor, Assistant Professor, the Department of Biotechnology. Belarusian State Technological University (13a Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: ignatovets@belstu.by

Kruk Mikalai Mikalaevich − DSc (Physics and Mathematics), Professor, Head of the Department of Physics. Belarusian State Technological University (13a Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: m.kruk@belstu.by

DOI: https://doi.org/ 10.52065/2520-6141-2025-290-4.

Key words: porphyrin, NO2-substitution, spectra, fluorescence, molecular orbitals, charge transfer state.

For citation: Lazovskaya O. I., Vershilovskaya I. V., Leontiev V. N., Ignatovets O. S., Kruk M. M. Spectralluminescent characteristics of NO2-substituted porphyrins. Proceedings of BSTU, issue 3, Physics and Mathematics. Informatics, 2025, no. 1 (290), pp. 20–25 (In Russian). DOI: 10.52065/2520-6141-2025-290-4.

Abstract

The spectral and luminescent characteristics of NO2-substituted porphyrins differing in the number of attached nitro groups and the architecture of peripheral substitution were studied with absorption and luminescence spectroscopy. It was found that the attachment of two nitro groups directly to the Cm- carbon atoms of the porphyrin macrocycle leads to significant bathochromic shifts of the bands in the absorption spectra and their broadening. It was found that the observed changes are due to the destabilization of the highest occupied molecular orbitals (HOMO) of the macrocycle and the rotation of nitro groups, which modulates the electronic communication of the substituents with macrocycle. Additional attachment of two nitro groups via phenyl spacer to other Cm-carbon atoms barely affects the electronic absorption spectra. The fluorescence spectra of the studied porphyrins have a broad structureless band with a Stokes shift of 1200 cm–1. The quantum yield of fluorescence of Φfl is as s low as 0.0014–0.0015. It is proposed that the fluorescence of the locally excited ππ*-state is completely quenched by population of a low-lying charge-transfer state (CT-state) and the observed luminescence is due to radiative deactivation of this CT-state.

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References

  1. Kruk M. M. Stroyeniye i opticheskiye svoystva tetrapirrol'nykh soyedineniy [Structure and optical properties of tetrapyrroliс compounds]. Minsk, BGTU Publ., 2019. 216 p. (In Russian).
  2. Monod J., Wyman J., Changeux J.-P. On the nature of allosteric transitions: a plausible model. Journal of Molecular Biology, 1965, vol. 12, no. 1, pp. 88−118.
  3. Pukhovskaya S. G., Ivanova Yu. B., Kruk M. M., Golubchikov O. A., Koifman O. I., Electronic and steric effects of substituents as a tool to control the properties of tetrapyrrolic macrocycles. Funktsional'nyye materialy na osnove tetrapirrol'nykh makrogeterotsiklicheskikh soyedineniy [Functional materials based on tetrapyrrole macroheterocyclic compounds]. Ed. by O. I. Koifman. Moscow, 2019, pp. 63–101 (In Russian).
  4. Murov S. L., Carmichael I., Hug G. L. Handbook of photochemistry. New-York, Marcel Dekker Publ., 1993. 420 p.
  5. Gouterman M., Wagniere G., Snyder L. R. Spectra of porphyrins. Part II. Four orbital model. Journal of Molecular Spectroscopy, 1963, vol. 11, no. 2, pp. 108−127.
  6. Gladkov L. L., Kruk M. M., Spectral manifestations of energy modulation of the porphine macrocycle electronic orbitals upon rotation of an NO2-substituent. Journ. Appl. Spectr., 2024, vol. 91, issue 5, pp. 963–968.
  7. Senge M. O. Exercises in molecular gymnastics – bending, stretching and twisting porphyrins. Chem. Commun., 2006, pp. 243–256.
  8. Knyukshto V. N., Zenkevich E., Sagun E., Shulga A., Bachilo S. Pathways for photoinduced electron transfer in meso-nitro-phenyl-octaethylporphyrins and their chemical dimers. Chem. Phys. Letters, 1999, vol. 304, no. 2, pp. 155−166.
  9. Vergeldt F. J., Koehorst R. B. M., van Hoek A., Schaafsma T. J. Intramolecular interactions in the ground and excited state of tetrakis(N-methylpyridyl)porphyrins. J. Phys. Chem., 1995, vol. 99, no. 13,
  10. pp. 4397–4405.

30.12.2024