Adsorption of UO2 2+, Tl+, Pb2+, Ra2+ and Ac3+ onto polyacrylamide-bentonite composite

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerization in a suspension of bentonite (B), the composite was then modified by phytic acid (PAA-B-Phy). The parameters related to adsorption of UO₂ ²⁺ in absence and presence of 0.01M CaCl₂ and of natural radionuclides (Tl⁺, Pb²⁺, Ra²⁺ and Ac³⁺ in a leaching solution) onto PAA-B and PAA-B-Phy, and thermodynamics of the adsorption were investigated. Adsorption isotherms were of L and H types for the adsorption of UO₂ ²⁺ onto PAA-B and PAA-B-Phy, whilst for Tl⁺, Pb²⁺, Ra²⁺ and Ac³⁺ they were of C type for both adsorbents. Langmuir equilibrium constants for the adsorption of all studied ions onto PAA-B-Phy were significantly higher than those found for PAA-B. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy. The composite of PAA-B and its modification by Phy have been used for the first time in this study. It is concluded that the composites can be practically used for adsorption and applied as adsorbent of radionuclides.     

Effect of solvent on the stability constant of complex formation and the thermodynamic parameters between dicyclohexyl-18-crown-6 with Eu3+, La3+, Er3+ and Y3+ cations

The complexation reaction between Eu³⁺, La³⁺, Er³⁺ and Y³⁺ cations with the dicyclohexyl-18-crown-6 (DCH18C6) in acetonitrile (AN)–dimethylformamide (DMF) and AN–methanol (MeOH) binary systems have been studied at different temperatures using conductometric method. The conductometric data show that the stoichiometry of the complexes is 1:1 [ML]. The results show that the stability constant of complexes in various solvents is: AN > MeOH > DMF. In the some cases, the minimum of logK_f for (DCH18C6–Eu³⁺), (DCH18C6–La³⁺), (DCH18C6–Er³⁺) and (DCH18C6–Y³⁺) complexes in AN–MeOH binary systems obtain at χ_MeOH ~ 0.75, and also, the logK_f of (DCH18C6–Er³⁺) complex in AN–DMF binary systems show a minimum at χ_AN ~ 0.75. Non-linear behavior was observed for the stability constant of complexes versus the composition of the solvent systems. The experimental data show that the selectivity order of DCH18C6 for these cations in AN–MeOH binary systems (mol% AN = 50, 75) at 25 °C is: Y³⁺ > Er³⁺ > Eu³⁺ > La³⁺. The values of thermodynamic parameters (?H?_C) for formation of complexes were obtained from temperature dependence of stability constants of complexes using the van′t Hoff plots and the standard entropy (?S?_C) were calculated from the relationship: ?G?_C, 298.15 = ?H?_C ?298.15?S?_C. The results show that the values of these thermodynamic parameters are influenced by the nature and the composition of the binary systems.     

Nitrate ion association with La3+, Gd3+, and Dy3+

Using the solvent extraction method it was found that the stability constantsK ₁ ⁰ of the La, Gd, DyNO₃ ²⁺ complexes are 41, 39, 21, respectively. The change of stability constants ofLnNO₃ ²⁺ complexes in the lanthanide series was related to the change of the amount of inner sphere complexation.

---

Zur Assoziation von Nitrationen mit La³⁺, Gd³⁺ und Dy³⁺

Zusammenfassung Mittels der Lösungsmittelextraktionsmethode wurden die Stabilitäts-konstantenK ₁ ⁰ von La, Gd und DyNO ₃ ²⁺ zu 41, 39 und 21 bestimmt. Der Unterschied der Stabilitätskonstanten derLnNO ₃ ²⁺ -Komplexe innerhalb der Lanthanidenserie wurde mit dem Wechsel der Inneren-Sphären-Komplexierung verknüpft.

     

Sorption of microamounts of Ce3+, Pm3+, Eu3+, Gd3+ and Yb3+ on aluminium hydroxide

The sorption of microamounts of trivalent lanthanides (Ln³⁺) on freshly precipitated Al(OH)₃ has been measured in dependence on pH and the time of sorption. Also, the influence of organic complexing ligands and inorganic electrolytes on the sorption process has been investigated. The mechanism of sorption is discussed. Freshly precipitated Al(OH)₃ can be used for the preconcentration of microamounts of trivalent lanthanides. However, the preconcentration is not quantitative in the presence of high concentrations of complexing ligands (citrate and similar) which form strong complexes with Ln³⁺ ions.     

Electron capture dissociation and collision-induced dissociation of metal ion (Ag+, Cu2+, Zn2+, Fe2+, and Fe3+) complexes of polyamidoamine (PAMAM) dendrimers

The electron capture dissociation (ECD) and collision-induced dissociation (CID) of complexes of polyamidoamine (PAMAM) dendrimers with metal ions Ag⁺, Cu²⁺, Zn²⁺, Fe²⁺, and Fe³⁺ were determined by Fourier transform ion cyclotron resonance mass spectrometry. Complexes were of the form [PD + M + mH]⁵⁺ where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2−4. Complementary information regarding the site and coordination chemistry of the metal ions can be obtained from the two techniques. The results suggest that complexes of Fe³⁺ and Cu²⁺ are coordinated via both core tertiary amines, whereas coordination of Ag⁺ involves a single core tertiary amine. The Zn²⁺ and Fe²⁺ complexes do not appear to involve coordination by the dendrimer core.     

Computational study of the interaction of metal ions (Na+, K+, Mg2+, Ca2+, and Al3+) with Quercetin and its antioxidant properties

In recent years, the chelation between quercetin and transition metals has attracted much attention because the complexes formed have higher antioxidant and medicinal activities. However, the theoretical investigation of the mechanisms of flavonoid functioning along with the structures of quercetin–metal complexes is still not sufficiently studied. In this research work, quercetin–complexes with Na⁺, K⁺, Mg²⁺, Ca²⁺, and Al³⁺ are studied theoretically by using density functional theory (DFT) method in order to investigate the stability, reactivity, nature of interaction, and the application of the quercetin-metal complexes as potential antioxidants. From the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) results, the K-quercetin salt was observed to be more stable as compared to the other metals while Ca seemed to be the most reactive with the least values in the neutral form of the metal - quercetin interaction. The results of the antioxidant activity in the neutral state present Ca and Mg to have the higher values of ionization potential (IP) indicating that the antioxidant activity of Ca/Mg complexes with quercetin are less pronounced, while K-complex with the least value indicating the higher the electron donating reactivity. In comparison, it is worth to note that Mg-Q and Ca-Q in the deprotonated state of quercetin showcase lower IP, higher ability of H-atom transfer and electron transfer reactivity, therefore, better antioxidant candidates of the quercetin complexes than their other counterparts.     

Synthesis,spectroscopic characterization and study the effect of gamma irradiation on VO2+, Mn2+, Zn2+, Ru3+, Pd2+, Ag+ and Hg2+ complexes and antibacterial activities

Novel complexes of VO²⁺, Mn²⁺, Zn²⁺, Ru³⁺, Pd²⁺, Ag⁺ and Hg²⁺ have been prepared by reacting their metal salts with ligand, named (4-(4-chlorophenyl)-1-(2-(phenylamino) acetyl) thiosemicarbazone). Study of synthesized metal complexes was confirmed by different analytical and spectral techniques (¹H NMR, MS, FT-IR, UV–Vis, EPR and Powder X-ray diffraction), thermogravimetric studies as well as molecular modeling. FT-IR spectra showed that the compound behave as neutral or monobasic tetradentate. In case of complexes of Mn²⁺, Zn²⁺, Ag⁺ and VO²⁺, through (N2H), (CO) or (CO) groups. While, the ligand behave as neutral bidentate in case of complexes with Pd²⁺ and Hg²⁺. X-ray diffraction pattern of Mn²⁺, Pd²⁺ and Ag⁺ complexes before and after irradiation are recorded. XRD studies exhibited that decrease in the crystalline size of sample Mn²⁺ as compared of samples Ag⁺ and Pd²⁺ upon irradiation and irradiation influenced the crystallinity of the complexes. The possible structures of the ligand, Mn²⁺, Pd²⁺ and Hg²⁺complexes have been computed by means of the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program. The bond length, bond angle, HOMO, LUMO and dipole moment have been studied to verify the geometry of Mn²⁺, Pd²⁺ and Hg²⁺ complexes. The effect of gamma irradiation was investigated by recording the new results of pervious spectroscopic techniques and other measurements. Thermal studies of these chelates before and after γ-irradiation showed that the complexes after γ-irradiation were more thermally stable than before γ-irradiation. The compound and its metal complexes have been experienced for their inhibitory outcome on the growth of microorganisms against gram positive and gram negative. The results proved that the complexes B₁–B₇ have potent antibacterial activity as compared to that of ligand.     

金属离子(Na~+、K~+、Ca~(2+)、Mg~(2+)、Zn~(2+))与鸟嘌呤异构体配合物的稳定性

在B3LYP/6-311++G**水平上用极化连续介质模型(PCM)系统研究了金属离子(M+/2+=Na+,K+,Ca2+,Mg2+,Zn2+)和十三种鸟嘌呤异构体形成的配合物GnxM+/2+(n为鸟嘌呤异构体的编号,x表示M+/2+与鸟嘌呤异构体的结合位点)在气(g)液(a)两相中的稳定性顺序.着重探讨了液相中配合物的稳定性差异,并且从溶质-溶剂效应、结合能、形变能及异构体的相对能量等几个方面分析了造成稳定顺序发生变化的原因.报道了溶液中这五种金属离子与鸟嘌呤异构体结合形成的六种基态配合物:aG1N2,N3Na+,aG1N2,N3K+,aG1O6,N7Ca2+,aG1N2,N3Mg2+(aG1O6,N7Mg2+),aG2N3,N9Zn2+.可以看出,除了在Zn2+配合物中鸟嘌呤异构体为G2外,构成其余四种金属离子配合物的鸟嘌呤异构体都是G1,但结合位点不同.同时对气相中各类配合物稳定性也进行了系统的排序,并报道了几种较稳定的配合物,如:gG3N1,O6K+,gG5N1,O6K+,gG3N1,O6Ca2+/Mg2+,gG4O6,N7Ca2+/Mg2+.     

Separation of strontium from simulated waste in K2SO4/Nitrate medium containing Sr2+, Eu3+, Ce3+, Pd2+, Rh3+, Ru3+, UO 2 2+ , Fe3+, Cr3+, Ni2+, Al3+, Ca2+ and Cs+, by strongly basic anion exchanger

In this work Strontium was separated selectively form, Pd²⁺, Ni²⁺ and Ca³⁺ using anionic resins of Amberlite type IRA-900 and IRA-410 from nitrate medium. The Separation of strontium by strongly basic anion exchangers IRA-410 and IRA-900 from simulated waste containing, Sr²⁺, Eu³⁺, Ce³⁺, Pd²⁺, Rh³⁺, Ru³⁺, VO₂ ²⁺, Fe³⁺, Cr³⁺, Ni²⁺, Al³⁺, Ca²⁺, and Cs⁺, in K₂SO₄/nitrate medium which adsorbed as strontium sulphate complex was achieved through ligand- ligan exchange. The elution of strontium carried out via “loading” the column with a solution of 0.03N EDTA in presence of 0.1N NaNO₃ at pH7 where Sr²⁺ has low K_d value. An inductively Coubled Plasma — Optical Emission Spectrometry (ICP — OES) of ARL type model 3520, was used for elemental analysis.     

Theoretical study of interaction of 2,6-dithiopurine with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cations

The geometries of the complexes of Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺ metal cations with different possible 2,6-dithiopurine anions (DTP) were studied. The complexes were optimized at the B3LYP level and the 6-311++G(d, p) basis set. The interactions of the metal cations at different nucleophilic sites of various possible 2,6-dithiopurine anions were considered. It was revealed that metal cations would interact with 2,6-dithiopurine anions in a bicoordinate manner. In the gas phase, the most preferred position for the interaction of Li⁺, Na⁺, and K⁺ cations is between the N₃ and S₂ sites, while all divalent cations Be²⁺, Mg²⁺, and Ca²⁺ prefer binding between the N₇ and S₆ sites of the corresponding 2,6-dithiopurine. The influence of aqueous solvent on the relative stability of different complexes has been examined using the Tomasi’s polarized continuum model. The basis set superposition error (BSSE) corrected interaction energy was also computed for complexes. The AIM theory has been applied to analyze the properties of the bond critical points (electron densities and their Laplacians) involved in the coordination between 2,6-dithiopurine anions and the metal cations. It was revealed that aqueous solution would have significant effect on the relative stability of complexes obtained by the interaction of 2,6-dithiopurine anions with Mg²⁺ and Ca²⁺ cations. The effect of metal cations on different NH and CS stretching vibrational modes of 2,6-dithiopurine has also been discussed.     

The Photophysical Properties of Quaternary Lanthanide (Eu3+, Tb3+, Sm3+, Dy3+) Functional Molecular Complexes

Summary. In this paper, according to the molecular fragment principle, a series of twelve quaternary luminescent lanthanide complex molecular systems were assembled. Both elemental analysis and infrared spectroscopy allowed to determine the complexes formula: Ln(Nic)₃(L)·H₂O, where Ln=Sm, Eu, Tb, Dy; HNic=pyridine-3-carboxylic acid; L=N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), pyrrolidone (pyro). The photophysical properties of these functional molecular systems were studied by recording both ultraviolet-visible absorption, phosphorescence, fluorescence excitation, and emission spectra. It was found that the conjugated pyridine-3-carboxylic acid acts as the main energy donor and luminescence sensitizer due to the suitable energy match and effective energy transfer to the luminescent Ln ³⁺ ions. Amide molecules (DMF, DMA, pyro) were only used as assistant structural ligands to enhance the luminescence. Especially the europium complexes show the strongest luminescence due to the optimum energy transfer between the HNic triplet state energy level and Eu³⁺.     

Synthesis,characterization, molecular modelling and biological activity of 2‐(pyridin‐1‐ium‐1‐yl) acetate and its Cu2+, Pt4+, Pd2+, Au3+ and Nd3+ complexes

A new series of Cu²⁺, Pt⁴⁺, Pd²⁺, Au³⁺ and Nd³⁺ complexes derived from 2‐(pyridin‐1‐ium‐1‐yl) acetate have been synthesized and characterized using elemental analyses, spectral (infrared (IR), UV–visible, mass, ¹³C NMR and ¹H NMR), magnetic and thermal measurements. IR results suggest that the ligand acts in a neutral monodentate fashion in all complexes. Octahedral geometry is proposed for Cu²⁺ and Pt⁴⁺ complexes and square‐planar for Pd²⁺ and Au³⁺ complexes. The bond lengths, bond angles, and HOMO and LUMO were calculated. Superoxide dismutase‐like radical scavenger activity and cytotoxic activity of the isolated complexes on HepG2 liver cancer cells have been screened. Ligand and complexes (Pt⁴⁺ and Nd³⁺) exhibit potent antioxidant activity upon coordination while Cu²⁺ and Au³⁺ complexes do not show superoxide dismutase‐like radical scavenger activity. The cytotoxic activity assay against HepG2 cell line proves that the ligand and its Pt⁴⁺ complex have a high cytotoxic activity, while the other complexes showed no cytotoxic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

VUV spectroscopic properties of rare-earth (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE³⁺- activated (RE³⁺ = Sm³⁺, Eu³⁺, Tb³⁺ and Dy³⁺) Ba₆Gd₉B₇₉O₁₃₈ borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE³⁺-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm³⁺-activated BGBO, the charge transfer transition from O^2- to Sm³⁺ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm³⁺ f-f transitions of ⁴G_5/2 → ⁶H_J (J = 5/2, 7/2 and 9/2). The O^2--Eu³⁺ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu³⁺-doped BGBO. For Tb³⁺-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb³⁺, respectively. In addition, the absence of the f-d transitions of Sm³⁺ and Dy³⁺ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators.     

Theoretical study on the interaction of glutathione with group IA (Li+, Na+, K+), IIA (Be2+, Mg2+, Ca2+), and IIIA (Al3+) metal cations

The structures and energies of complexes obtained upon interaction between glutathione (GSH) and alkali (Li⁺, Na⁺, K⁺), or alkaline earth metal (Be²⁺, Mg²⁺, Ca²⁺), or group IIIA (Al³⁺) cations were studied using quantum chemical density functional theory. The characteristics of the interactions between GSH and the metal cations at different nucleophilic sites of GSH were examined selecting systematically, both mono- and multi-coordinating were taken into account. The results indicated that the heteroatom of GSH, the radius and charge of metal ion, and the coordination number of the metal cation with the ligand played important roles in determining the stability of these complexes. Moreover, the intramolecular hydrogen migration in GSH could be promoted by the metal cations during coordination reaction. Furthermore, the Al³⁺ cation might catalyze the decarboxylation reaction and stimulate the formation of covalent bond between S atom and adjacent O atom of GSH.     

Thermodynamic parameters of TI+, Ra2+, Bi3+and Ac3+ adsorption onto polyhydroxyethylmethacrylate-hydroxyapatite composite

In this research, a new composite, poly (hydroxyethylmethacrylate-hydroxyapatite) [P(HEMA-Hap)], was synthesized and its adsorptive features for natural radionuclides (TI⁺, Ra²⁺, Bi³⁺and Ac³⁺ in a leaching solution) were investigated at differing initial pH, concentration and temperature ranges. The natural radionuclides were counted by gamma spectrometer using a type NAI (Tl) detector. The adsorption data obtained were well represented by Langmuir and Freundlich type isotherms. The magnitude of determined monolayer adsorption capacities (X _L) for the adsorbed radionuclides were TI⁺ = Ac³⁺ > Ra²⁺ = Bi³⁺. These results demonstrated that P(HEMA-Hap) had high affinity to the natural radionuclide. The thermodynamic parameters indicated that the adsorption mechanisms were spontaneous (ΔG < 0) in terms of adsorption free enthalpy, and changes in the enthalpy and entropy values showed that the overall adsorption process was endothermic (ΔH > 0), thus increasing entropy (ΔS > 0).     

Geometrical structure and nonlinear response variations of metal (M = Ni2+, Pd2+, Pt2+) octaphyrin complex derivatives: A DFT study

Nonlinear optical response of designed organometallic complexes of Ni²⁺, Pd²⁺, and Pt²⁺ metal ions with octaphyrin (OP) as ligand were explored by using DFT at CAM-B3LYP/6–311G++(d, p)/LANL2DZ/DEF2SV level of theory. The geometries of these organometallic complexes were studied in terms of effect on molecular framework by metal ion and substituent groups. The optimized geometry of free ligand displays that one of the four pyrrole rings orients out of plane to reduce the steric hindrance. The effect of the substituents on the geometry was found more prominent in the Ni²⁺-OP complexes. The calculations reveal enhancement in the values of dipole moment and hyperpolarizability on introducing electron withdrawing and electron donating groups in ligand framework with maximum enhancement in case of Pt²⁺-OP derivatives. In this study no regular trend was observed for the HOMO and LUMO energies with the second-order hyperpolarizability of M²⁺-OP complexes. However, we have observed that the excited-state properties calculated by using TD-DFT correlate well with the second-order hyperpolarizability values and the dependence was rationalized in terms of two-level model. Thus, from overall calculations we have observed that the designed organometallic complexes display higher polarizability and hyperpolarizability values and can be effective candidates for nonlinear response.     

Synthesis of New LnxBi2–xSe3 (Ln: Sm3+, Eu3+, Gd3+, Tb3+) Nanomaterials and Investigation of Their Optical Properties

New Ln_xBi_2–xSe₃ (Ln: Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺) based nanomaterials were synthesized by a co‐reduction method. Powder XRD patterns indicate that the Ln_xBi_2–xSe₃ crystals (Ln = Sm³⁺, Eu³⁺, x = 0.00–0.44 and Ln = Gd³⁺, Tb³⁺, x = 0.00–0.50) are isostructural with Bi₂Se₃. The cell parameter c decreases for Ln = Eu³⁺, Gd³⁺, Tb³⁺ upon increasing the dopant content (x), while a slightly increases. Changes in lattice parameters could be related to the radii of cations. SEM images show that doping of the lanthanide ions in the lattice of Bi₂Se₃ generally results in nanoflowers. For the terbium compound two kinds of morphologies (nanoflowers and nanobelts) were observed. UV/Vis absorption and emission spectroscopy reveals mainly electronic transitions of the Ln³⁺ ions. Emission spectra show intense transitions from the excited to the ground state of Ln³⁺ and energy transfer from the Bi₂Se₃ lattice. Emission spectra of europium‐doped materials, in addition to the characteristic red emission peaks of Eu³⁺, show an intense blue emission band centered at 432 nm, originating from the 4f⁶5d¹ to 4f⁷ configuration in Eu²⁺. EPR measurements confirm the existence of Eu²⁺ in the materials. Interestingly, for all samples starting at low Ln³⁺ concentration, the emission intensity rises to a maximum at a Ln³⁺ concentration of x = 0.2 and falls again steadily to a minimum at x = 0.45.     

Investigation on the upconversion luminescence of Sr3AlO4F:Yb3+, Er3+, Ho3+ phosphors

To develop new emission-tunable upconversion (UC) phosphors, the Sr₃AlO₄F:5%Yb³⁺, xEr³⁺, yHo³⁺ (0 ≤ x ≤ 1%, 0 ≤ y ≤ 1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980 nm excitation were studied. Upon 980 nm excitation, Yb³⁺-Er³⁺ codoped Sr₃AlO₄F shows a predominant emission peak between 645 and 700 nm which is attributed to the ⁴F_9/2-⁴I_15/2 transition of Er³⁺, and the Er³⁺ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb³⁺-Ho³⁺ codoped Sr₃AlO₄F, three emissions are observed obviously which are all derived from the Ho³⁺ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr₃AlO₄F:5%Yb³⁺, 0.2%Er³⁺, 1%Ho³⁺ phosphor was developed, and its emission spectrum includes the emission peaks of both Er³⁺ and Ho³⁺. Correspondingly, the sample gives a yellow emission.     

Mono- and Mixed Metal Complexes of Eu3+, Gd3+, and Tb3+ with a Diketone,Bearing Pyrazole Moiety and CHF2-Group: Structure,Color Tuning,and Kinetics of Energy Transfer between Lanthanide Ions

Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL₃(H₂O)₂], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [Eu_xTb_1-xL₃(H₂O)₂] (Eu_xTb_1-xL₃), [EuxGd_1-xL₃(H₂O)₂] (Eu_xGd_1-xL₃), and [Gd_xTb_1-xL₃(H₂O)₂] (Gd_xTb_1-xL₃), were studied. The Eu_xTb_1-xL₃ complexes exhibit the simultaneous emission of both Eu³⁺ and Tb³⁺ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu³⁺. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb³⁺ and Eu³⁺ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation.