Self-Assembly of a Two-Dimensional Coordination Polymer Based on Silver and Lanthanide Tetrakis-Acylpyrazolonates: An Efficient New Strategy for Suppressing Ligand-to-Metal Charge Transfer Quenching of Europium Luminescence

Yury A Belousov; Mikhail T Metlin; Darya A Metlina; Mikhail A Kiskin; Ilya A Yakushev; Trofim A Polikovskiy; Ilya V Taydakov; Andrei A Drozdov; Fabio Marchetti; Claudio Pettinari

doi:10.3390/polym15040867

Self-Assembly of a Two-Dimensional Coordination Polymer Based on Silver and Lanthanide Tetrakis-Acylpyrazolonates: An Efficient New Strategy for Suppressing Ligand-to-Metal Charge Transfer Quenching of Europium Luminescence

Polymers (Basel). 2023 Feb 9;15(4):867. doi: 10.3390/polym15040867.

Authors

Affiliations

¹ Chemistry Department, M.V. Lomonosov Moscow State University, Leninskie Gory Str, Building 1/3, 119991 Moscow, Russia.
² P. N. Lebedev Physical Institute of Russian Academy of Sciences, Leninsky Prospect 53, 119991 Moscow, Russia.
³ Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Leninsky Prospekt 31, 119991 Moscow, Russia.
⁴ School of Science and Tecnology, Chemistry Interdisciplinary Project (ChIP), University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy.
⁵ School of Pharmacy, Chemistry Interdisciplinary Project (ChIP), University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy.

Abstract

A new strategy for the easy polymerization of anionic [Ln(Q^cy)₄]^- (HQ^cy-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) into two-dimensional layers of [AgLn(Q^cy)₄]_n (Ln = Sm, Eu, Gd, Tb and Dy) is proposed by binding the single molecular anions [Ln(Q^cy)₄]^- to silver cations through the coordination of the pyridinic nitrogen atoms of the pyrazolonate rings. The luminescent properties of [AgLn(Q^cy)₄]_n have been studied in detail, and it was shown that the previously described low photoluminescence quantum yield (PLQY) of [Eu(Q^cy)₄]^- is due to Ligand-To-Metal Charge Transfer (LMCT) quenching, which is effectively suppressed in the heterometallic [AgEu(Q^cy)₄]_n polymer. Sensibilization coefficients for H₃O[Eu(Q^cy)₄], [AgEu(Q^cy)₄]_n, and H₃O[Sm(Q^cy)₄] complexes (n ≈ 1) were estimated via theoretical analysis (also by using Judd-Ofelt theory for Sm³⁺) and PLQY measurements.

Keywords: LMCT quenching; coordination polymers; europium; heterometallic complexes; lanthanides; luminescence; pyrazolonates; silver.

Grants and funding

19-13-00272/Russian Science Foundation