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

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 (H2 O)2 ] (1a), [Ho(ntfa)3 (MeOH)2 ] (1b), (1), [Ho(btfa)3 (phen)] (2), [Ho(btfa)3 (bipy)] (3), [Ho(btfa)3 (di-t bubipy)] (4), [Ho(ntfa)3 (Me2 bipy)] (5), and [Ho(ntfa)3 (bipy)] (6), where phen is 1,10-phenantroline, bipy is 2,2′-bipyridyl, di-t bubipy is 4,4′-di-tert-butyl-2,2′-bipyridyl, and Me2 bipy 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 (λex ) 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).