Synthesis and Characterization of Anionic Lanthanide(III) Complexes with a Bidentate Sulfonylamidophosphate (SAPh) Ligand

Abstract

A series of new anionic lanthanide(III) complexes with the general formula NEt 4 [LnL 4 ] (1-Ln; HL = dimethyl[(4-methylphenyl)sulfonyl]amidophosphate; Ln = La, Nd, Eu), were synthesized and characterized by IR, UV− vis, and NMR spectroscopies, the differential scanning calorimetry method, thermogravimetric and X-ray analysis, and photoluminescence measurements. Single-crystal structures of NEt 4 [EuL 4 ] (1-Eu) were determined at 293 and 100 K and evidenced the single-crystal-to-single-crystal phase transition. Both phases are in the monoclinic crystal system in centrosymmetric groups of the same Laue class. The room temperature structure is in C2/c (No. 15), while lowtemperature structure is in the P2 1 /c (No. 14) space groups. The coordination environment geometry around the central europium(III) ion is a distorted square antiprism in both polymorphs, while the peripheral methoxy and tolyl groups show different orientations. This phenomenon indicates the occurrence of a thermally driven second-order phase transition during the cooling−heating process. The europium(III) complex exhibits an unusual emission spectrum, clearly dominated by the 5 D 0 − 7 F 4 bands, and an emission decay time equaling 3.5 ms, being among the highest values known for europium coordination compounds.

New Luminescent Lanthanide Tetrakis‐Complexes NEt4[LnL4] Based on Dimethyl‐N‐Benzoylamidophosphate

“…The luminescence bands relative intensities ratio 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 (red/orange ratio) at 298 K equals 2.6 being the lowest known to date for CAPh based europium complexes, pointing to higher symmetry of the Eu 3+ site in NEt 4 [EuL 4 ] compared to Cs[EuL 4 ]. However, for sulfonylamidophospate based europium tetrakis ‐complex of similar composition NEt 4 [EuSAPh 4 ] much lower value of red/orange ratio (1.2) was observed [27] . It is worth noticing that the 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 intensity ratio cannot be used to compare site symmetry for europium compounds with different ligands, since the polarizability of the ligands plays a very important role here [61] .…”

“…The luminescence spectrum of NEt ] much lower value of red/orange ratio (1.2) was observed. [27] It is worth noticing that the 5 D 0 ! 7 F 2 / 5 D 0 !…”

“…In 2018 the first examples of triboluminescent CAPh based lanthanide tetrakis‐complexes were reported [12] . The lanthanide(III) tetrakis‐complexes with the general formula (cation)[Ln(Lig) 4 ] (where Lig − =β‐diketonate or SAPh − or CAPh − ) have been extensively studied recently [13–34] . In their structure, a lanthanide ion is surrounded by four ligands forming a LnO 8 environment and the cationic counterparts are typically alkali metal ions or positively charged N, P‐organic cations.…”

Visible-light excitable, highly transparent and luminescent films with an ultrahigh loading of a europium(III) complex

“…The anions and cations interact via van der Waals and electrostatic forces. 13 The possible p-p stacking mode is excluded during crystal packing, despite the presence of plentiful aromatic ring fragments in the structure (Fig. S4, ESI †).…”

THE COORDINATION COMPOUNDS Gd (III) AND Dy(III) WITH SOME β-DIKETONES

“…In general, the energy of the resonance level of the metal should be somewhat lower than the energy of the triplet level of the ligand, which neutralizes the nonradiative deactivation of the resonance level together with a high probability and efficiency of the emitting transition. The overwhelming majority of studies in this area are on lanthanide complexes emitting in the visible region of the spectrum, in particular, Eu(III), Tb(III), Sm(III), Nd(III), Yb(III) [12,20,[22][23][24][25][26]. Although dysprosium compounds (III) are also capable of emitting in the visible region of the spectrum, such studies are limited due to the complexity of the ligand selection.…”