Tuning Nuclearity of Biradical-Ln Functional Compounds with Single-Molecule Magnet Behavior and Near-Infrared Luminescence

Abstract

Utilizing an hexadentate nitronyl nitroxide biradical bisNITbpym, two series of biradical-4f clusters, namely [Tb2(hfac)6(bisNITbpym)2]·CHCl3 (1), [Dy2­(hfac)6­(bisNITbpym)2] (2), and [Ln4 (hfac)12 (bisNITbpym)2] (LnIII = YIII 3, TbIII 4 and YbIII 5) (bisNITbpym = 2,2′-di­pyridyl-5,5′-bis­(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetra­meth­yl-4,5-hydro-1H-imidazol-2-yl); hfac = hexa­fluoro­acetyl­acetonate), have been smoothly obtained via regulating the ratio of LnIII metal to biradical bisNITbpym. In compounds 1 and 2, the bisNITbpym ligand links two TbIII ions to yield a dinuclear pattern. Meanwhile, 3–5 exhibit an annular tetranuclear structure with biradical bisNITbpym, enwrapping and bridging four LnIII ions. Single-molecule magnet behavior of the Dy derivate is confirmed through frequency-dependent ac signals. Furthermore, this comparative exploration of dinuclear and tetranuclear systems indicates that spatial symmetries around LnIII ions have an important impact on magnetic dynamics. Near-infrared luminescence and slow magnetic relaxation have been observed in the YbIII derivative, which can act as a promising multifunctional probe in the aspect of fluoroimmuno assays. Our present work not only successfully acquires a multifunctional YbIII-based compound but also achieves the regulation of nuclearity and magnetic property of the nitronyl nitroxide biradical-LnIII system.

Structure and assembly studies of two planar Dy(iii) single molecule magnets with double relaxations

“…This kind of behavior is believed to be caused by the synergistic effect of thermally reduced Stark energy levels and intermetallic magnetic interactions or dipole–dipole interactions. 58–60…”

“…This kind of behavior is believed to be caused by the synergistic effect of thermally reduced Stark energy levels and intermetallic magnetic interactions or dipole-dipole interactions. [58][59][60] The field-dependent magnetizations of 1 and 2 measured at 2.0, 3.0 and 5.0 K were plotted as M-H and M-HT À1 curves (Fig. S9, ESI †), respectively.…”

Lanthanide–radical single-molecule magnets: current status and future challenges

“…Notably, up to now, most of the nitronyl nitroxide-lanthanide SMMs rely mainly on mono-radicals and the research of biradicalbridged Ln SMMs remains in its infancy on account of the synthetic challenge. [64][65][66][67][68][69][70][71][72][73][74] Nitronyl nitroxide biradicals have two prominent advantages: (i) they possess four NO groups and can construct diverse topologies by means of linking to several metal ions; (ii) intramolecular magnetic coupling between two mono-radicals is able to be regulated via an appropriate conjugated spacer. The first nitronyl nitroxide biradical-4f compound was reported in 2010.…”