D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

P. V. Strekalov, Postgraduate Student
K. I. Runina, Lead Engineer
O. B. Petrova, Professor at the Department of Crystal Chemistry and Technology, Doctor of Chemical Sciences, e-mail: petrova@muctr.ru

Prokhorov General Physics Institute of the Russian Academy of Sciences, Federal Research Centre, Moscow, Russia:

M. N. Mayakova, Research Fellow at the Science Centre for Laser Materials and Technology, Candidate of Chemical Sciences

Powder hybrid materials based on the organic phosphor 8-hydroxyquinolate lithium and the inorganic matrix PbF₂ have been synthesized. Powder hybrid materials were obtained by co-precipitation from aqueous-alcoholic solutions with ammonium fluoride under various conditions – different concentrations of the organic component, precursor solutions, the order of mixing the reagents: direct precipitation and reverse precipitation, providing a local excess of nitrate or fluorinating agent during the synthesis. Hybrid materials are single-phase powders, whose crystal structure corresponds to the rhombic phase of α-PbF₂. All obtained hybrid materials showed effective broadband luminescence in the region of 390–700 nm. The shift of the photoluminescence bands to longer wavelengths relative to the initial Liq is observed, which is characteristic of lead luminescent complexes, which suggests the formation of new optical cents associated with Pbq₂ or [PbqF]₂, for all obtained hybrid materials. The formation of optical centers occurs as a result of an exchange reaction and the formation of new bonds between lead and organic ligands. Moreover, an increase in the concentration of the initial Pb(NO₃)₂ solution promotes a more complete course of the exchange reaction (up to 88%). During reverse deposition, a large fraction of Liq is captured by the crystallizing lead fluoride molecularly, and the completeness of the exchange reaction is generally lower than during direct deposition. The photoluminescence intensity during reverse deposition is 3 to 10 times higher than during direct deposition for different concentrations of reagents. The most intense luminescence is provided by the conditions of reverse precipitation with ammonium fluoride of a solution of lead nitrate with a concentration of 0.8 M and a Liq content of 1 wt.%.
This research was funded by the Russian Science Foundation, Grant No. 19-79-10003.

1. Avnir D., Levy D., Reisfeld R. The nature of silica cage as reflected by spectral changes and enhanced photostability of trapped rhodamine 6G. The Journal of Physical Chemistry. 1984. Vol. 88. pp. 5956–5959.
2. Sanchez C., Ribot F. Design of hybrid organic-inorganic materials synthesized via sol-gel chemistry. New Journal of Chemistry. 1994. Vol. 18. pp. 1007–1047.
3. Parola S., Julián-López B., Carlos L. D., Sanchez C. Optical Properties of Hybrid Organic-Inorganic Materials and their Applications. Advanced Functional Materials. 2016. Vol. 26. pp. 6506–6544.
4. Anurova M. O., Runina K. I., Khomyakov A. V., Taydakov I. V., Petrova O. B. et al. The effect of borate glass matrix on the luminescence properties of organic–inorganic hybrid materials. Physics and Chemistry of Glasses: European Journal of Glass Science and Technology. Part B. 2019. Vol. 60, No. 4. pp. 140–145.
5. Petrova O., Avetisov R., Akkuzina A., Anurova M., Mozhevitina E. et al. Luminescent stability of hybrids based on different borate glass matrix’s and organic metal complexes. IOP Conference Series: Materials Science and Engineering. 2017. Vol. 225. p. 012083.
6. Petrova O. B., Anurova M. O., Akkuzina A. A., Saifutyarov R. R., Ermolaeva E. V. et al. Luminescent hybrid materials based on (8-hydroxyquinoline)-substituted metal-organic complexes and lead-borate glasses. Optical Materials. 2017. Vol. 69. pp. 141–147.
7. Runina K. I., Sekacheva A. Yu., Petrova O. B. Solid-phase synthesis of luminescent organic-inorganic hybrid materials. Uspekhi v khimii i khimicheskoy tekhnologii. 2020. Vol. 34, No. 4. pp. 80–82.

8. Saifutyarov R., Petrova O., Taydakov I., Akkuzina A., Barkanov A. et al. Optical properties transformation under laser treatment of hybrid organic-inorganic thin films. Physica Status Solidi (A) Applications and Materials Science. 2019. p. 1800647.
9. Petrova O. B., Runina K. I., Mayakova M. N., Taydakov I. V., Khomya kov A. V. et al. Luminescent hybrid materials based on metal-organic phosphors in PbF₂ powder and PbF₂-containing glass matrix. Optical Materials. 2018. Vol. 88. pp. 378–384.
10. Runina K. I., Mayakova M. N., Petrova O. B. Lead fluoride and organic phosphor based organic-inorganic luminescent hybrid materials. Uspekhi v khimii i khimicheskoy tekhnologii. 2019. Vol. 33, No. 8. pp. 33–35.
11. Sevostianova T. S., Khomyakov A. V., Mayakova M. N., Voronov V. V., Petrova O. B. Luminescent properties of solid solutions in the PbF2 – EuF3 system and of lead fluoroborate glass ceramics activated with Eu³⁺ ions. Optics and Spectroscopy. 2017. Vol. 123, No. 5. pp. 734–744.
12. Fedorov P. P., Kuznetsov S. V., Mayakova M. N., Voronov V. V., Ermakov R. P. et al. Coprecipitation from aqueous solutions to prepare binary fluorides. Russian Journal of Inorganic Chemistry. 2011. Vol. 56. pp. 1525–1531.
13. Mayakova M. N., Voronov V. V., Iskhakova L. D., Kuznetsov S. V., Fedorov P. P. Lowtemperature phase formation in the BаF₂ – CeF₃ system. Journal of Fluorine Chemistry. 2016. Vol. 187. pp. 33–39.
14. TU 2612-007-56853252–2010. High-purity hydrofluoric acid. Part 27-5. Khimki : Sigma Tek, 2010.
15. Najafi E., Amini M. M., Mohajerani E., Janghouri M., Razavi H. et al. Fabrication of an organic light-emitting diode (OLED) from a two-dimensional lead(II) coordination polymer. Inorganica Chimica Acta. 2013. Vol. 399. pp. 119–125.
16. Akkuzina A. A., Kozlova N. N., Gornak A. A., Khomyakov A. V., Mozhevitina E. N. et al. Spectral and luminescent properties of high-purity crystalline lithium 8-oxyquinolate. Uspekhi v khimii i khimicheskoy tekhnologii. 2016. Vol. 30, No. 3. pp. 118–120.