Heteroleptic Lanthanide Complexes Coordinated by Tripodal Tetradentate Ligand: Synthesis, Structure, and Magnetic and Photoluminescent Properties

Abstract

We report the synthesis, structures, magnetic and luminescent properties of a series of heteroleptic lanthanide complexes based on a tripodal tetradentate ligand[Ln(Tpma)(NO 3 ) 3 ]•nMeCN (Ln = Eu (1), Tb (2), Dy (3), Er (4), n = 0.5; Yb (5), n = 0; Tpma = tris((1H-pyrazol-1-yl)methyl)amine). The europium, terbium and dysprosium analogues exhibit a lanthanide-based luminescence, while dysprosium, erbium and ytterbium compounds show a field-induced slow relaxation of their magnetization involving Raman and direct processes.

Tripodal Oxazolidine-N-Oxyl Diradical Complexes of Dy3+ and Eu3+

“…The χ m T value at 300 K of 14.735 emu K mol −1 for 1 is slightly smaller than the theoretical value of 14.92 emu K mol −1 at the non-interacting limit from two radicals (S = 1/2, g = 2.0023, 0.375 emu K mol −1 ) and one Dy III ion (4f 9 , S = 5/2, L = 5, J = 15/2, g J = 4/3, 6 H 15/2 , 14.17 emu K mol −1 ). This value is, however, in good agreement with the those of 14.365 emu K mol −1 , previously obtained for the monoradical complex [DyRad(NO 3 ) 3 ] [27] taking into account the fact that the experimental values for dysprosium in a related coordination environment are somewhat lower than those for a free ion: 13.92-14.00 [43,44]. On cooling, the χ m T value remains virtually unchanged up to 90 K, and then gradually decreases down to 10 emu K mol −1 at 20 K and finely drops to 4.803 emu K mol −1 at 2 K. The last value is considerably lower than that for the monoradical analogue (6.50 emu K mol −1 ).…”

Synthesis, Structures, and Luminescent Properties of Chloride and Nitrate LnIIIComplexes Coordinated by tris(Pyrazolyl)methane

“…[14] The YbÀ N distances in 1Yb hrm proved to be slightly elongated compared to the previously reported nitrate complex [Yb(Tpma)(NO 3 ) 3 ] (2.365(3)-2.453(3) Å; Tpma = tris((1H-pyrazol-1-yl)methyl)amine). [15] The EuÀ N bond lengths in 1Eu fall into the range typical for EuÀ N distances in previously reported Eu 3 + nitrate complexes coordinated by neutral polydentate pyrazolyl containing ligands (2.494(6)-2.657(2) Å). [16][17][18][19][20][21][22] The YbÀ O (2.3689(5)-2.4099(5) Å) and EuÀ O (2.440(2)-2.490(2) Å) bonds in 1Ln have lengths close to those in nine-coordinate complexes (YbÀ O 2.320(4)-2.492(4) Å, EuÀ O 2.452(3)-2.479(3) Å).…”

“…The Ln−N bond lengths in 1Yb hrm and 1Eu are significantly different: 2.4317(4), 2.4628(4), 2.4792(4) Å for 1Yb hrm ; 2.515(2), 2.543(2) 2.563(2) Å for 1Eu , what caused by their different ionic radii (Yb 3+ : 1.042 Å; Eu 3+ : 1.120 Å; CN=9) [14] . The Yb−N distances in 1Yb hrm proved to be slightly elongated compared to the previously reported nitrate complex [Yb(Tpma)(NO 3 ) 3 ] (2.365(3)–2.453(3) Å; Tpma=tris((1 H ‐pyrazol‐1‐yl)methyl)amine) [15] . The Eu−N bond lengths in 1Eu fall into the range typical for Eu−N distances in previously reported Eu 3+ nitrate complexes coordinated by neutral polydentate pyrazolyl containing ligands (2.494(6)–2.657(2) Å) [16–22] .…”

Lanthanide Complexes with Tripodal Ligands

“…In contrast, a small group of heteroleptic complexes containing three nitrates and one tripodal tetradentate ligand tris((1H-pyrazol-1-yl)methyl)amine) (TPzMA) are enough axial, Figure 4-23a [12]. The authors present the synthesis, structures, and photophysical and magnetic properties of a sequence complexes [Ln(TPzMA)(NO3)3]•nMeCN (Ln = Eu, Tb, Dy, Er, n = 0.5; Yb, n = 0).…”

“…Moreover, the latter can be easily varied by using the methods of synthetic organic chemistry. Therefore, it is not surprising that tripodal ligands are widely used in various fields of applied coordination chemistry such as catalysis [1][2][3][4][5][6], chemo sensing [7][8][9], photo- [10][11][12] and electroluminescence [11,13,14], molecular gears and motors production [15,16], biomedical applications [17][18][19][20] and molecular magnetism [12,[21][22][23][24].…”