Intensive emission of Eu(iii) β-diketonate complexes with arsine oxide ligands

Abstract

Europium(iii) hexafluoroacetylacetonates incorporating arsine oxides were synthesized. Tris(1-naphthyl)arsine oxide yielded a notably more intense emission and higher thermal stability than triphenylphosphine oxide, which is conventionally used.

Boosting the Luminescence of a Europium(III)–β-Diketonate Complex–Nanoclay Aqueous Solution by Acetylcholine

“…For Eu 3+ (TTA n )-NC, the excitation spectrum obtained by monitoring the 5 D 0 – 7 F 2 transition at 612 nm is a broad band in the range of 220–420 nm with two peaks at 250 and 350 nm, which can be ascribed to the absorption of the TTA ligand and overlapped with the UV–vis absorption spectrum shown in Figure S1, implying the energy transfer from TTA to Eu 3+ ions . There are five sharp bands at around 579, 595, 612, 655, and 701 nm assigned to the transitions of 5 D 0 → 7 F J ( J = 0–4) with 5 D 0 → 7 F 2 as the dominant one, indicating Eu 3+ ions located at a site without inversion symmetry, alike that of europium­(III)–β-diketonate complexes. − The emission spectra of Ch + -Eu 3+ (TTA n )-NC and ACh + -Eu 3+ (TTA n )-NC are highly analogous to those of Eu 3+ (TTA n )-NC, but a remarkable enhancement in the intensity of these spectra is observed, and the PLQY increases from 9.2 to 55.4 and 56.8% upon addition of ChCl and AChCl, respectively, meaning that ChCl and AChCl can significantly boost the luminescence of Eu 3+ (TTA n )-NC. In addition, the intensity ratio I ( 5 D 0 → 7 F 2 )/ I ( 5 D 0 → 7 F 1 ) increases from 7.8 to 16.8 and 17.2 after the addition of ChCl and AChCl, respectively, indicative of the much lower symmetry of Eu 3+ sites and a larger Eu 3+ -ligand interaction .…”

Highly Efficient and Thermally Durable Luminescence of 1D Eu3+ Coordination Polymers with Arsenic Bridging Ligands

“…These frequency values are comparable to those reported in our reports on discrete Eu 3 + complexes with monodentate arsine oxides (864-892 cm À 1 ). [9] The SC-XRD analysis demonstrated that the Ln 3 + center has an eight-coordinate geometry consisting of two pnictide oxides and three hfa ligands in the Ln 3 + coordination polymers. The distortion of the Ln 3 + center geometry was evaluated using continuous shape measurements, [12] estimating the shape value S, which is given by Equation (1):…”

“…The absorption edges were shifted to the longer wavelength region than those of the reported mononuclear Eu 3 + complex, [Eu(hfa) 3 (tpao) 2 ] (tpao: triphenylarsine oxide). [9] These long-wavelength absorption bands are assigned to intra-ligand charge transfer (ILCT) states caused by the densely packed structure. Notably, for 2-a and 5-a bridged by bisarsine oxides, shoulder peaks were observed around 380 nm in both cases, suggesting a similar ILCT state.…”

“…The k nr values of the Eu 3 + coordination polymers (380-490 s À 1 ) were reduced compared to those of the reported mononuclear Eu 3 + complexes (400-540 s À 1 ) because the molecular vibration was effectively suppressed by the formation of CH/F interactions between the polymer chains. [9] Besides, the radiative rate constant (k r ) values of the 4 f-4 f emission were increased as a result of the construction of a polymeric structure. Thus, high luminescence quantum yields (Φ f-f � 69 %) were obtained for both Eu 3 + coordination polymers.…”

“…[8] Furthermore, the Eu(hfa) 3 (hfa; hexafluoroacetylacetonate) complex of tri(1-naphthylarsine) oxide exhibits highly efficient red emission in both the solution (quantum yield when the f-f transition is directly excited (465 nm), Φ f-f = 72 %) and solid states (Φ f-f = 74 %). [9] This Eu 3 + complex has a high thermal stability (temperature at which the sample lost 5 wt% of its original mass, T d5 = 557 K) and exhibits bright luminescence even at 500 K. Thus, arsine oxides have emerged as promising alternatives to conventionally applied phosphine oxides. However, to date, there are only mononuclear Ln 3 + complexes with monodentate arsine oxide ligands in terms of arsine oxide-ligated Ln 3 + complexes.…”