Kateryna Borysova

Chemistry

Student

Taras Shevchenko National University of Kyiv/L. V. Pisarzhevskii Institute of Physical Chemistry

CV: Bachelor of chemistry (Taras Shevchenko National University of Kyiv). Now graduate student of Inorganic chemistry department and engineer in L.V. Pisarzhevskii Institute of Physical Chemistry of the NAS of Ukraine with the current research interests in coordination chemistry of 4f-metals and luminesce spectroscopy. Alumni of the «Internship Programme of German Business for Ukraine 2021» funded by GIZ GmbH (Deutsche Gesellschaft für Internationale Zusammenarbeit).

Presenting about:

Luminescent properties of Eu(III) and Tb(III) tris(3-(2'-pyridyl)-pyrazolyl)borate complexes with co-ligand containing a redox-active fragment of 2,6-di(tert-butyl)phenol

Abstract: Luminescence properties of lanthanide ions coordination compounds are widely known because of the broad area of their potential use. In this research field, the most interesting and complex task is to study the influence of external factors on Ln(III) coordination compounds spectral properties as far as control of their characteristics is challenging, being dependent on many factors, which, on the one hand, restrains the use of Ln(III) complexes in modern technology, and on the other – determines and supports the relevance of basic research in this area.
In this study, we design hetero ligand lanthanide complexes, i.e., with the presence of a ligand that will act as «antenna-ligand» and the other co-ligand - as a sensitive to the external factors, the so-called photo- /or redox-active. 2,6-di(tert-butyl)phenol derivatives are well-known for the ability of phenoxyl radicals’ formation under UV-light or oxidation with PbO2. It can be expected that the formation of such radicals in the Ln(III) complex should affect their luminescence intensity. Hence, the purpose of this study was to determine the effect of the generation of new paramagnetic centers, in particular phenoxyl radicals, on the intensity of Eu(III) and Tb(III) -centered emission in tris(pyrazolyl)borate coordination compounds.
Complexes exhibit intense metal-centered emission with high luminescence quantum yields up to 21% for Eu(III) and 50% for Tb(III), respectively. Both ligands can perform the role of «antenna» depending on the wavelength of the excitation light. In the case of UV-irradiation influence, the emission intensity of compounds decreases significantly under UV-irradiation due to the generation of a phenoxyl radical from the 2,6-di(tert-butyl)phenolic fragment, which leads to quenching of luminescence with the bit efficient but reversible effect. Complexes also show photochromic behavior under sunlight. Such experimental results suggest the potential use of such compounds as sensors on UV-radiation effects on food, medicine, or optical materials.