Magnetic and Luminescence Properties of 8-Coordinate Holmium(III) Complexes Containing 4,4,4-Trifluoro-1-Phenyl- and 1-(Naphthalen-2-yl)-1,3-Butanedionates

Franz A Mautner; Florian Bierbaumer; Ramon Vicente; Saskia Speed; Ánnia Tubau; Mercè Font-Bardía; Roland C Fischer; Salah S Massoud

doi:10.3390/molecules27031129

Magnetic and Luminescence Properties of 8-Coordinate Holmium(III) Complexes Containing 4,4,4-Trifluoro-1-Phenyl- and 1-(Naphthalen-2-yl)-1,3-Butanedionates

Molecules. 2022 Feb 8;27(3):1129. doi: 10.3390/molecules27031129.

Authors

Franz A Mautner¹, Florian Bierbaumer¹, Ramon Vicente², Saskia Speed², Ánnia Tubau², Mercè Font-Bardía³, Roland C Fischer⁴, Salah S Massoud^{5

6}

Affiliations

¹ Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria.
² Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain.
³ Departament de Mineralogia, Cristallografia i Dipòsits Minerals and Unitat de Difracció de R-X, Centre Científic i Tecnològic de la Universitat de Barcelona (CCiTUB), Universitat de Barcelona, Solé i Sabarís 1-3, 08028 Barcelona, Spain.
⁴ Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria.
⁵ Department of Chemistry, University of Louisiana at Lafayette, P.O. Box 43700, Lafayette, LA 70504, USA.
⁶ Department of Chemistry, Faculty of Sciences, Alexandria University, Moharam Bey, Alexandria 21511, Egypt.

Abstract

A new series of mononuclear Ho³⁺ complexes derived from the β-diketonate anions: 4,4,4-trifluoro-1-phenyl-1,3-butanedioneate (btfa^-) and 4,4,4-trifuoro-1-(naphthalen-2-yl)-1,3-butanedionate (ntfa^-) have been synthesized, [Ho(btfa)₃(H₂O)₂] (1a), [Ho(ntfa)₃(MeOH)₂] (1b), (1), [Ho(btfa)₃(phen)] (2), [Ho(btfa)₃(bipy)] (3), [Ho(btfa)₃(di-^tbubipy)] (4), [Ho(ntfa)₃(Me₂bipy)] (5), and [Ho(ntfa)₃(bipy)] (6), where phen is 1,10-phenantroline, bipy is 2,2'-bipyridyl, di-^tbubipy is 4,4'-di-tert-butyl-2,2'-bipyridyl, and Me₂bipy is 4,4'-dimethyl-2,2'-bipyridyl. These compounds have been characterized by elemental microanalysis and infrared spectroscopy as well as single-crystal X-ray difraction for 2-6. The central Ho³⁺ ions in these compounds display coordination number 8. The luminescence-emission properties of the pyridyl adducts 2-6 display a strong characteristic band in the visible region at 661 nm and a series of bands in the NIR region (excitation wavelengths (λ_ex) of 367 nm for 2-4 and 380 nm for 5 and 6). The magnetic properties of the complexes revealed magnetically uncoupled Ho³⁺ compounds with no field-induced, single-molecule magnet (SMMs).

Keywords: X-ray; diketones; holmium; lanthanides; luminescence; magnetic properties.