Search Results (4)

In this study, we report the growth and comprehensive spectroscopic analysis of TmF₃-doped CaF₂ crystals, grown using the vertical Bridgman method. The optical absorption and photoluminescence properties of both trivalent (Tm³⁺) and divalent (Tm²⁺) thulium ions were investigated. Optical absorption spectra in the UV-VIS-NIR range reveal characteristic transitions of Tm³⁺ ions, as well as weaker absorption bands corresponding to Tm²⁺ ions. The Judd–Ofelt (JO) formalism was applied to determine the intensity parameters Ω₂, Ω₄, and Ω₆, which were used to calculate radiative transition probabilities, branching ratios, and radiative lifetimes for the Tm³⁺ ions. The emission spectra showed concentration-dependent quenching effects, with significant emissions observed for the concentration of 0.1 mol% TmF₃ under excitation at 260 nm and 353 nm for Tm³⁺ ions and at 305 nm for Tm²⁺ ions. A new UV emission associated with divalent Thulium is reported. The results indicate that higher TmF₃ concentrations lead to increased non-radiative energy transfer, which reduces luminescence efficiency. These findings contribute to the understanding of the optical behavior of Tm-doped fluoride crystals, with implications for their application in laser technologies and radiation dosimetry. Full article

A lanthanide contraction(LC) of 14 lanthanides (Ln) from ₅₈Ce to ₇₁Lu consists of the interaction of Ln nucleus with 4f-electrons. Rare earth elements (REEs—R) include Sc, Y, La, and 14 Ln. They are located in 4–6th periods of the subgroup of group III. The electronic structure divides R into short (d- Sc, Y, La) and long (14 f-elements Ce-Lu) homologous series. The most important chemical consequence of LC is the creation of a new conglomerate of 16 RF₃ by mixing fluorides of d- (Y, La) and f-elements. This determines the location of YF₃ among LnF₃. The location of YF₃ depends on the structural (formula volumes—V_form) and thermochemical (temperatures and heats of phase transformations, phase diagrams) properties. The location of YF₃ between HoF₃ and ErF₃ was determined by V_form at a standard pressure (P_st) and temperature (T_st). The location of YF₃ according to heats of phase transformations ΔH_fus and ΔH_trans is in a dimorphic structural subgroup (SSGr) D (Ln = Er-Lu), but without the exact “pseudo Z_Y”. According to the temperatures of phase transformations (T_trans) in LnF₃ (Ln = Dy-Lu), YF₃ is located in the SSGr D between ErF₃ and TmF₃. The ErF₃-YF₃ and YF₃-TmF₃ phase diagrams show it to be between ErF₃ and TmF₃. The crystals of five β-LnF₃ (Ln = Ho-Lu) and β-YF₃ were obtained in identical conditions and their crystal structures were studied. V_form (at P_st and T_st) with “pseudo” atomic number Z_Y = 67.42 was calculated from the unit cell parameters, which were defined with ±5 × 10⁻⁴ Å accuracy. It determines the location of YF₃ between HoF₃ and ErF₃. Full article

With Tm₃F[Si₃O₁₀], a new representative of the Ln₃F[Si₃O₁₀] series could be synthesized by the reaction of Tm₂O₃, TmF₃ and SiO₂ (molar ratio: 1:1:3), applying an excess of CsBr as a fluxing agent in gas-tightly sealed platinum crucibles for eight days at 750 °C, and designed to yield Tm₃F₃[Si₃O₉] or Cs₂TmF[Si₄O₁₀]. Single crystals of Tm₃F[Si₃O₁₀] (monoclinic, P2₁/n; a = 725.04(6), b = 1102.43(9), c = 1032.57(8) pm, β = 97.185(7)°; Z = 4) appear as pale celadon, transparent, air- and water-resistant rhombic plates. According to its thalenite-type structure, Tm₃F[Si₃O₁₀] contains catena-trisilicate anions [Si₃O₁₀]⁸⁻ and triangular [FTm₃]⁸⁺ cations. The three crystallographically different Tm³⁺ cations are coordinated by seven plus one (Tm1) or only seven anions (Tm2 and Tm3) exhibiting a single F⁻ anion for each polyhedron, additional to the majority of O²⁻ anions. Furthermore, the luminescence properties of the isotypic colorless compound Y₃F[Si₃O₁₀] doped with Eu³⁺ (red emission), Tb³⁺ (green emission) and Er³⁺ (yellow and infrared emission), respectively, are reported in presenting their different excitation and emission spectra. Full article

We previously reported the potential anti-proliferative activity of 3-(5,6,7-trimethoxy-4-oxo-4H-chromen-2-yl)-N-(3,4,5-trimethoxyphenyl) benzamide (TMS-TMF-4f) against human cancer cells; however, the underlying molecular mechanisms have not been investigated. In the present study, TMS-TMF-4f showed the highest cytotoxicity in human cervical cancer cells (HeLa and CaSki) and low cytotoxicity in normal ovarian epithelial cells. Annexin V-FITC and propidium iodide (PI) double staining revealed that TMS-TMF-4f-induced cytotoxicity was caused by the induction of apoptosis in both HeLa and CaSki cervical cancer cells. The compound TMS-TMF-4f enhanced the activation of caspase-3, caspase-8, and caspase-9 and regulated Bcl-2 family proteins, which led to mitochondrial membrane potential (MMP) loss and resulted in the release of cytochrome c and Smac/DIABLO into the cytosol. Also, TMS-TMF-4f suppressed both constitutive and IL-6-inducible levels of phosphorylated STAT3 (p-STAT3) and associated proteins such as Mcl-1, cyclin D1, survivin, and c-Myc in both cervical cancer cells. STAT-3 overexpression completely ameliorated TMS-TMF-4f-induced apoptotic cell death and PARP cleavage. Docking analysis revealed that TMS-TMF-4f could bind to unphosphorylated STAT3 and inhibit its interconversion to the activated form. Notably, intraperitoneal administration of TMS-TMF-4f (5, 10, or 20 mg/kg) decreased tumor growth in a xenograft cervical cancer mouse model, demonstrated by the increase in TUNEL staining and PARP cleavage and the reduction in p-STAT3, Mcl-1, cyclin D1, survivin, and c-Myc expression levels in tumor tissues. Taken together, our results suggest that TMS-TMF-4f may potentially inhibit human cervical tumor growth through the induction of apoptosis via STAT3 suppression. Full article