Ferromagnetic ordering of –[Sm(iii)-radical]_n– coordination polymers

Abstract

[Sm(hfac)3(boaDTDA)]n is the first coordination compound of a thiazyl-based neutral radical ligand to exhibit ferromagnetic ordering; TC = 3 K. The [Sm(iii)-radical]n species is soluble in common organic solvents and can be sublimed quantitatively. A McConnell I mechanism is implicated in local exchange pathways that contribute to cooperative magnetic properties.

Probing magnetic order and disorder in the one-dimensional molecular spin chains CuF2(pyz) and [Ln(hfac)3(boaDTDA)] n (Ln = Sm, La) using implanted muons

“…However, the lack of oscillations and the behaviour of the dynamic relaxation suggests that the Ln =Sm ferromagnetic transition seen previously involves significant dynamic fluctuations in the muon spin-precession time window, which is typically sensitive to correlation times of order τ ≈ 0.1 − 10 ns. This is also consistent with the reported ac susceptibility measurements, where a response was noted in the out of phase component χ close to 3 K [13]. We might therefore speculate that the ferromagnetically ordered state likely has a finite correlation length below T c , with fluctuations over a broad range of timescales freezing out in a spatially inhomogeneous manner as the temperature is lowered.…”

“…1, bottom). The 1D chains pack such that the heteroatoms of the boaDTDA ligands do not allow any close contacts between chains [12,13]. Materials with Ln =La and Sm were both found to show 1D ferromagnetic exchange interactions between the radical spins, mediated via the Ln 3+ ions [12,13].…”

“…Consequently, the entropy change on ordering will be much reduced compared to a more isotropic system and may prevent specific heat measurements from detecting a transition [7]. For this reason sensitive magnetic measurement techniques such as muon-spin relaxation (µ + SR) have found a use in detecting the transitions to long range magnetic order that allow us to quantify the strength of the interchain exchange and reveal how well real materials are described by idealised models [9,6,10] In this paper we present µ + SR measurements on two different 1D coordination polymer systems: (i) the quasi-1D Heisenberg antiferromagnet CuF 2 (pyz), built from (boaDTDA) is the radical ligand 4-(benzoxazol-20-yl)-1,2,3,5-dithiadiazolyl and hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato [12,13]. In both systems, the muon relaxation is dominated by the magnetism of the nuclear spins in the high-temperature paramagnetic regime owing to the rapid fluctuations of the electronic spins on the timescale of muon spin precession.…”

Effects of Halo-Substitution on 2′-Chloro-5′-halo-phenyl-1,2,3,5-dithiadiazolyl Radicals: A Crystallographic, Magnetic, and Electron Paramagnetic Resonance Case Study

“…[3][4][5][6][7][8][9][10] In the majority of cases these radicals associate in the solid state to form π*-π* dimers, although a number of monomeric DTDA radicals have been reported. 1,2,[11][12][13][14][15][16] This dimerization is typically associated with short intra-dimer S···S contacts around 2.9 -3.1 Å.…”

Highly Selective Sub-ppm Naked-Eye Detection of Hydrazine with Conjugated-1,3-Diketo Probes: Imaging Hydrazine in Drosophila Larvae

“…This observation clearly reveals that the optical responses of 1 and 2 are not affected by the presence of the other analytes, and hence, compounds 1 and 2 can be used as probes for the detection of a trace quantity of hydrazine in aqueous samples with high selectivity. It is interesting to note that, in spite of bearing an acetylacetonate moiety, the fluorescence intensity of each of the chemodosimeters is not perturbed at all by the lanthanides, especially samarium­(III), , plausibly due to the restriction in keto–enol tautomerism, as well as by nucleophiles (cyanide, CN – ; glutathione, GSH; thiols, RSH). It was hydrazine that solely perturbed the fluorescence responses of 1 and 2 in the presence of other analytes potentially to similar extents.…”