Lanthanide(III) (Eu, Gd, Tb, Dy) Complexes Derived from 4‐(Pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole: Crystal Structure, Magnetic Properties, and Photoluminescence

Abstract

The reaction of lanthanide(III) nitrates with 4-(pyridin-2-yl)methyleneamino-1,2,4-triazole (L) was studied. The compounds [Ln(NO ) (H O) ]⋅2 L, in which Ln=Eu (1), Gd (2), Tb (3), or Dy (4), obtained in a mixture of MeCN/EtOH have the same structure, as shown by XRD. In the crystals of these compounds, the mononuclear complex units [Ln(NO ) (H O) ] are linked to L molecules through intermolecular hydrogen-bonding interactions to form a 2D polymeric supramolecular architecture. An investigation into the optical characteristics of the Eu -, Tb -, and Dy -containing compounds (1, 3, and 4) showed that these complexes displayed metal-centered luminescence. According to magnetic measurements, compound 4 exhibits single-ion magnet behavior, with ΔE /k =86 K in a field of 1500 Oe.

Synthesis, Characterization and Crystal Structure of Samarium(III)-(E)-1-phenyl-N-(4H-1,2,4-triazol-4-yl)methanimine Complex

“…The [Sm(H 2 O) 3 (NO 3 ) 3 ] entity interconnect with two triazol rings via HO(12 OH 2 )…N( 5 3). It should be noted that a similar intermolecular hydrogen-bond contact was observed for several trivalent lanthanides (Eu, Gd, Tb, Dy, Ce) with triazole [39,60] . Furthermore, intramolecular hydrogen-bond contacts involve the OH groups of the coordinated water molecules and the O-NO 2 of the nitrate of adjacent [Sm(NO 3 ) 3 (H 2 O) 3 ].…”

“…Coordination polymers of silver(I) and cadmium(II) with the polydentate N-donor ligand 4-(pyridin-2-yl)methyleneamino-1,2,4-triazole (L) were studied previously [36][37][38] . Moreover, lanthanide(III) (Eu, Gd, Tb, Dy) complexes derived from 4-(pyridin-2yl)methyleneamino-1,2,4-triazole were also prepared [39] . In continuation to recent research work [40] , herein, we investigated the reaction of Sm(III) nitrates with E-1-phenyl-N-(4H-1,2,4triazol-4-yl)methanimine.…”

Unexpected Supremacy of Non‐Dysprosium Single‐Ion Magnets within a Series of Isomorphic Lanthanide Cyanocobaltate(III) Complexes

“…In contrast, complexes built by ligands which violate or completely break sandwich geometry [ 8a,13,17r,17y,18a–18j ] are significantly inferior as SMMs. There is also one more important peculiarity common for all champions, namely chemical equality of donating centers due to conjugation within phthalocyanine cycles.…”

“…Compounds not possessing sandwich‐type geometry of Tb environment also exhibit lesser SMM characteristics. [ 8a,8f,8g,13,17b–17d,17r–17v,18b,18c,18f–18h ]…”

“…This trend originates from chemical nature of these systems virtually always comprising rigid polydentate ligands, e.g. aromatic N‐donors, [ 18b,24j ] Schiff bases, [ 24g ] β‐diketonate anions, [ 24l ] etc. This, first, does not allow one to achieve particular low‐distorted geometry desirable for maximization of the anisotropy, and, second, may result in unfavorably ambiguous geometry of Yb 3+ polyhedron.…”