The effect of the second coordination sphere on the magnetism of [Ln(NO₃)₃(H₂O)₃]·(18-crown-6) (Ln = Dy and Er)

Abstract

The impact of the second coordination sphere on the magnetic properties of [Ln(NO3)3(H2O)3]·(18C6) compounds comprising co-crystallized 18-crown-6 ethers was investigated.

Structural Trends in a 3 d‐4 f System: Ln(NO3)3−Cu(2,2‐bipyridine)2(NO3)2 (Ln=La−Nd, Sm−Yb)

“…[Dy(NO 3 ) 3 (H 2 O) 4 ]⋅2H 2 O was found to exhibit magnetic field induced SMM property at low temperature . On the other hand, the same compound as well as its Er analog when crystallised with a crown ether, the non‐covalently bonded crown ether was shown to induce normal (zero static field) SMM behaviour . Some of the simple (nitrato and aquonitrato) lanthanide complex species reported here, especially the later members of the series with high ground state J ‐values, may show SMM property.…”

“…[57] On the other hand, the same compound as well as its Er analog when crystallised with a crown ether, the non-covalently bonded crown ether was shown to induce normal (zero static field) SMM behaviour. [58] Some of the simple (nitrato and aquonitrato) lanthanide complex species reported here, especially the later members of the series with high ground state J-values, may show SMM property. However, the presence of Cu(II) complex ions in the proximity of the lanthanide species, though not covalently linked, may enhance the relaxation rate.…”

Pseudo-Tetrahedral vs Pseudo-Octahedral ErIII Single Molecule Magnets and the 'Disruptive' Role of Coordinated TEMPO Radicals

“…Compared to the tetrahedral 1 and 3, the octahedral 4 performs worse as an SMM due to the much less favourable, higher-symmetry ligand scaffold as previously observed for several Er III complexes with coordination numbers exceeding 6. [48][49][50][51][52][53][54][55] Finally, our detailed magneto-structural and theoretical study of the pseudo-tetrahedral 1 and 3, clearly shows that in the presence of a small external magnetic field, the slow magnetic relaxation in these two SMMs is fully governed by the Raman relaxation process instead of Orbach in the whole investigated AC magnetic susceptibility temperature and frequency range. This observation again calls for a better understanding of this most basic relaxation process in the lanthanide-based SMMs.…”

De novodesigned coiled coils as scaffolds for lanthanides, including novel imaging agents with a twist

“…70 As with other metals, the coordination environment has been shown to play an essential role in the activity and behaviour of lanthanide complexes. [102][103][104] Thus, if the true potential of lanthanide-protein assemblies is to be realised, the ability to rationally design lanthanide binding sites with predictable chemistry is essential. Coiled coils are a class of ligands which benefit from many of the advantages afforded by protein ligands without much of the complexity.…”

“…101 Specific to lanthanide complexes, secondary coordination sphere effects in small molecules complexes have been shown to alter their stability, 102 luminescent 101 and magnetic properties. 104 Thus it is clear that control of the secondary coordination sphere is highly desirable, and something which is achievable with coiled coil peptide systems.…”