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Registration Number

0222U000790, 0120U100133 , R & D reports

Title

The effect of redox reactions on the photoluminescence of lanthanides in different valence states in oxide-halide crystals and complexes

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Head

Dotsenko Volodymyr P., Доктор хімічних наук

Registration Date

18-01-2022

Organization

Physico-Chemical Institute O. Bogatsky National Academy of Sciences of Ukraine

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 The object of the research is the formation of Eu2+-emitting centers in alkaline earth chloroborates and silicates, modification of tetrapyrrole ligands and their complexes with halogen-containing lanthanide fragments. The purpose of the work is to analyze the effect of halogen-ion on the optical and fluorescent properties of Ln(II)/(III) lanthanides in oxide-halide crystals; synthesis of lanthanide complexes with halogen-containing tetrapyrroles and analysis of factors that determine luminescent characteristics and photostability of the obtained complexes. It is shown that the long wavelength position of the Eu2+emission maximum in Ca2BO3Cl (λmax= 576 nm) is caused by two factors: the large crystal field splitting of the Eu2+ 4f65d configuration of the Eu2+ ion and the relatively high degree of covalence of the metal-ligand bond. It is concluded that the long-time afterglow of Ca2BO3Cl:Eu2+,Ce3+ is due to the photoinduced Eu2+→ Eu3+ transition with subsequent capture of delocalized electrons by host lattice defects. It is shown that doped with Eu2+ and Ce3+ ions calcium chloroborates and silicates of composition Ca2BO3Cl, Ca3SiO4Cl2 are promising materials for night safety signs. Synthesis methods of lanthanide complexes with tetrapyrrole macrocycles modified by halogen-containing fragments have been developed. It has been shown that in a series of ortho-meta-para isomers intramolecular intercombinational transitions are slowed down by influencing of the heavy atom, which leads to an increase of quantum yield and lifetime of the molecular fluorescence. The ways of excitation energy transfer in ytterbium-containing phthalocyanines are proposed. It is shown that quenching of the fluorescence may be the result of a fast transition from a singlet state to a state of charge transfer, which is due to the transition of π electrons from the phthalocyanine orbital to the orbital of the Yb(III) ion with the reduction of the latter to the divalent state Yb(II).

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Ieriomin Oleg G.
Efryushina Ninel P.
Berezovskaya Irina V.
Volchak Ganna V.
Doha Pavlo G.
Dotsenko Volodymyr P.
Zheltvay Ivan I.
Zinchenko Viktor F
Korovin Oleksandr Yu.
Kucher Albert O.
Magunov Igor R.
Pochinoc Elvira V.
Rusakova Nataliia V.
Sadkovska Liudmyla V.
Semenishyn Mykola M.
Smola Serhiy S.
Stamikosto Olena V.
Stoianova Iryna V.
Tesluk Olga І.
Khomenko Olena V.
Chivireva Natalia О.

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2022-03-09