Luminescent, magnetic and ferroelectric properties of noncentrosymmetric chain-like complexes composed of nine-coordinate lanthanide ions

Abstract

Reaction of the chiral ligand (-)-4,5-pinenepyridyl-2-pyrazine (L) with Ln(hfac)3·2H2O precursors [hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate, Ln = Sm(3+) (1), Eu(3+) (2), Tb(3+) (3) and Dy(3+) (4)] in methanol solution led to the formation of four noncentrosymmetric lanthanide complexes with the general formula [Ln(hfac)3L]n·H2O. The single-crystal X-ray diffraction analyses revealed that they are isostructural and take a one-dimensional (1D) chain structure based on the Ln(hfac)3L repeating units, in which the nine-coordinate Ln(3+) ions reside in a tricapped trigonal prism (TTP) environment never reported in previous 1D chain lanthanide complexes. The investigations of their photophysical properties showed that complexes 1, and 3 exhibit characteristic emissions of Sm(3+), Eu(3+) and Tb(3+) ions with respective luminescent lifetime values of 0.065, 1.066 and 0.129 ms, while complex 4 does not display any emission. The different luminescent intensities and lifetimes among them were further discussed in detail. Moreover, the magnetic properties of complexes 1-4 were assessed with a special emphasis on the Dy(3+) complex 4. Alternating-current (ac) magnetic susceptibility measurements indicated that field-induced two-step slow magnetic relaxation processes were observed in 4, indicating the single-molecule magnet (SMM) behavior of 4. In addition, the noncentrosymmetric complexes 1-4 crystallizing in the same polar point group (Cs) exhibit both ferroelectric and nonlinear optical properties at room temperature. All these features make them multifunctional crystalline molecule materials.

Single molecule magnet of flexible Salen-type dysprosium coordination polymer with 1D ionic chain structure

“…5). The effective relaxation energy barrier of U eff / κ Β = 30.3 K and pre-exponential factor τ 0 = 6.33 × 10 −6 s. To our knowledge, among 1D Dy systems, this energy barrier is lower than the reported values of 44.0 K in [DyL 3 (HOCH 2 CH 2 OH)] n (L = 2-furoate anion) [13a], and higher than the value of 16.35 K in Dy(hfac) 3 L [16] (hfac − = 1,1,1,5,5,5-hexafluoroacetylacetonate, L = (−)-4,5-pinene pyridyl-2-pyrazine). But it is better than the other reported rare 1D chain Salen-type dysprosium coordination polymers [9], in which no frequency-dependent peak is observed.…”

Synthesis, Structure and Properties of an Erbium(III) Complex with Chiral Salen‐type Schiff Base Ligand

“…The ferroelectric behavior of ErL was also examined given that P 2 1 space group belongs to the C 2 polar point groups required for ferroelectric materials 24–26. The ferroelectric property was investigated at room temperature with single crystal samples and shown in Figure 4.…”

“…Absorption corrections were applied using SADABS 23. The structures were solved by direct methods and refined with the full‐matrix least‐squares technique using SHELXS‐97 and SHELXTL‐97 programs, respectively 24. Anisotropic thermal parameters were applied to all non‐hydrogen atoms.…”

Synthesis, Structure, and Magnetic Properties of a Family of Complexes Containing a {CoII2DyIII} Pivalate Core and a Pentanuclear CoII4DyIII Derivative

“…Heterometallic complexes containing 3d and 4f ions are interesting subjects for studies aimed at understanding magnetic interactions as well as important components and precursors for the creation of functional and multifunctional materials , . The high probability of single‐molecule magnetism (SMM) seems to be the primary reason for the interest in such systems,, but lanthanide complexes have other unique properties, such as the possible combination of nontrivial magnetic behavior with luminescence .…”