Pentagram-type Ln15 (Ln = Dy, Tb, Eu, Sm, Ho) clusters with different anion templates: magnetic and luminescence properties

Five 15-nucLearity Lanthanide dusters were obtained under soLvothermaL conditions based on N-tris(hydroxymethyOmethyLgLycine (H 5 thmmg) with moLecuLar formulas Ln(15)(OH)(20)(H(4)thmmg)(10)(H2O)(10)center dot xCl center dot(15 - x) NO3 (Ln = Dy, x = 15 (1); Ln = Tb, x = 11 (2); Ln = Eu, x = 13 (3); Ln = Sm, x= 15 (4); and Ln = Ho, x = 15 (5)). They have the same pentagram-type metal cores made up of five cubane-Like [Ln(4)(mu(3)-OH)(4)] units by sharing vertical Ln(3+) ions and their peripheries are aLL protected by ten H(4)thmmg - ligands and ten coordinated H2O. Such structural Sm-15 and Ho-15 dusters are reported for the first time. For 1, 4 and 5, these metal-hydroxide cores are further stabilized only by free Cl- ions, whereas NO3- and Cl (-) ions both operate as anionic tempLates for 2 and 3 to balance the positive charge and to promote Lanthanide metal ion aggregation. These are the first reported Ln(15) dusters self-assembled by NO3- and Cl- anion tempLates. The Luminescence behaviors of 2 and 3 show the characteristic emissions of the corresponding Ln(3+) (Ln = Tb, Eu) ions. The temperature-dependent Luminescence of 2 and 3 reveals that their emission intensities increase as the temperature drops, and good Linear relationships exist in the 120-300 K range, so 2 and 3 are potential Luminescent moLecuLar thermometers. Moreover, 2 and 3 exhibit high quantum yields (QYs) (58.05% for 2 and 17.34% for 3) and Long Luminescence Lifetimes (tau = 934 mu s for 2, tau = 242 mu s for 3). In addition, 1 displays slow magnetic relaxation behavior.

Automated summary

In this study, five 15-nuclearity lanthanide dusters were synthesized using N-tris(hydroxymethylglycine) as a ligand. The structures of Sm-15 and Ho-15 were reported for the first time. The dusters 2 and 3 exhibited potential as luminescent molecular thermometers with high quantum yields and long luminescence lifetimes.