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

A new series of mononuclear Ho3+ complexes derived from the beta-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-(t)bubipy)] (4), [Ho(ntfa)(3)(Me(2)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 Me(2)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 (lambda(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).

Automated summary

A series of mononuclear Ho3+ complexes derived from beta-diketonate anions have been synthesized and characterized. These complexes exhibit a coordination number of 8 for the central Ho3+ ions. The pyridyl adducts show strong luminescence emissions in the visible and near-infrared regions. The magnetic properties of the complexes reveal no field-induced single-molecule magnet behavior.