Highly Luminescent and Thermally Stable Lanthanide Coordination Polymers Designed from 4-(Dipyridin-2-yl)aminobenzoate: Efficient Energy Transfer from Tb³⁺ to Eu³⁺ in a Mixed Lanthanide Coordination Compound

Abstract

Herein, a new aromatic carboxylate ligand, namely, 4-(dipyridin-2-yl)aminobenzoic acid (HL), has been designed and employed for the construction of a series of lanthanide complexes (Eu(3+) = 1, Tb(3+) = 2, and Gd(3+) = 3). Complexes of 1 and 2 were structurally authenticated by single-crystal X-ray diffraction and were found to exist as infinite 1D coordination polymers with the general formulas {[Eu(L)(3)(H(2)O)(2)]}(n) (1) and {[Tb(L)(3)(H(2)O)].(H(2)O)}(n) (2). Both compounds crystallize in monoclinic space group C2/c. The photophysical properties demonstrated that the developed 4-(dipyridin-2-yl)aminobenzoate ligand is well suited for the sensitization of Tb(3+) emission (Φ(overall) = 64%) thanks to the favorable position of the triplet state ((3)ππ*) of the ligand [the energy difference between the triplet state of the ligand and the excited state of Tb(3+) (ΔE) = (3)ππ* - (5)D(4) = 3197 cm(-1)], as investigated in the Gd(3+) complex. On the other hand, the corresponding Eu(3+) complex shows weak luminescence efficiency (Φ(overall) = 7%) due to poor matching of the triplet state of the ligand with that of the emissive excited states of the metal ion (ΔE = (3)ππ* - (5)D(0) = 6447 cm(-1)). Furthermore, in the present work, a mixed lanthanide system featuring Eu(3+) and Tb(3+) ions with the general formula {[Eu(0.5)Tb(0.5)(L)(3)(H(2)O)(2)]}(n) (4) was also synthesized, and the luminescent properties were evaluated and compared with those of the analogous single-lanthanide-ion systems (1 and 2). The lifetime measurements for 4 strongly support the premise that efficient energy transfer occurs between Tb(3+) and Eu(3+) in a mixed lanthanide system (η = 86%).

A New Tricarboxylate‐Terbium(III) Compound: Synthesis, Structure, and Luminescent Property

“…As shown in Figure 4a, two intense emission bands at 490 and 543 nm are assigned to the electronic transitions from the excited state 5 (Figure 4b), which are all comparable to other related Tb III compounds with the photoluminescence efficiency of 63.68 %, 64 %, respectively. [14][15][16] …”

Thermostable Eu(III)-nanorod luminophores with effective photosensitized energy transfer

“…The decrease in the decomposition temperatures of [Eu(hfa) x (DPP) y ] n and [Eu(hfa) x (TP-PO) y (DPP) z ] n is caused by the elimination of organic hfa and TPPO ligands in the Eu-DPP materials. The highest decomposition temperature for a luminescent lanthanide polymers composed of Ln(III) ions and organic ligands was previously reported to be 450 C. 7 In this study, we successfully prepared thermostable Eu(III) coordination polymers such as a Eu(III) doped inorganic ceramics. Eu(III) nanoparticle aggregates [Eu(hfa) x (DPP) y ] n and Eu(III)-nanorod aggregates [Eu(hfa) x (TPPO) y (DPP) z ] n provide significant thermo-stability for opto-engineering applications.…”

“…The periodical structures lead to improvement of the thermal stability with suppression of thermal relaxation under high temperatures. Reddy and Guo have discussed thermostable lanthanide coordination polymers with 4-(dipyridine-2-yl)aminobenzoate ligands (decomposition temperature ¼ 450 C) [7] and 1,4-benzendicarboxylic acid (decomposition temperature ¼ 400 C) [8], respectively. We have reported thermostable luminophores constructed with lanthanide ions and organo-phosphine oxides (decomposition temperature > 300 C).…”

Water-soluble Tb3+ and Eu3+ complexes based on task-specific ionic liquid ligands and their application in luminescent poly(vinyl alcohol) films

“…Moreover, the intensity ratio of the red to green emission decreases obviously with increasing the Tb 3+ concentrations, and the emission colors of the films thus varied from red, orange, yellow, light green to green correspondingly. However, according to the equation (1) as follow: 49,50 η = 1τ 1 /τ 0 (1) where τ 1 and τ 0 are the excited state lifetimes of the donor in the presence and absence of the acceptor, the energy transfer from Tb 3+ to Eu 3+ is not obviously observed in the films at room temperature. Fig.…”