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Updated: Dec 21, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
Excitation-Dependent Photoluminescence Color Tuning in Lanthanide-Organic Hybrid Materials
R Lee Ayscue1, Chloe P Verwiel1, Jeffery A Bertke1
1Department of Chemistry, Georgetown University, 37th and O Streets, Northwest, Washington, DC 20057, United States.
Abstract:
A series of lanthanide organic hybrid materials was synthesized via hydrothermal methods and structurally characterized using single-crystal X-ray diffraction. Four phases were obtained from reactions of La, Eu, and Tb ions with 1,10-phenanthroline (phen) and 2-thiophenecarboxylate (TC): [La2(phen)2(k1-TC)2(μ2-TC)2(η3-TC)2(H2O)2] (La-1/La-2), [Eu2(phen)2(k2-TC)2(μ2-TC)2(η3-TC)2]·2(H2O) (Eu-3), and [Tb2(phen)2(k2-TC)2(μ2-TC)4]·2(H2O) (Tb-4). Although each of the structures consists of homometallic ligand bridged dimers, the four distinct phases arise from subtle differences in ligand binding modes and supramolecular interactions. Ln doping was explored and resulted in analogous heterometallic systems, [Eu2-La(phen)2(k2-TC)2(μ2-TC)2(η3-TC)2]·2(H2O) (EuLa-3; x = 0.47-1.51) and [Tb2-La(phen)2(k2-TC)2(μ2-TC)4]·2(H2O) (TbLa-4; y = 0.42, 0.67). The photoluminescent properties of the solid-state materials were assessed using steady-state and time-dependent techniques to obtain excitation and emission profiles, transition energies, and lifetimes. The La phase exhibited ligand-based emission, whereas both Eu and Tb phases produced characteristic red and green metal-centered emission, respectively. By comparison, the heterometallic compounds exhibited both Ln- and ligand-based emission and photoluminescent color tuning of emission chromaticity. Further examination revealed that the color tuning was dependent on the relative La/Eu or La/Tb ratios as well as the excitation wavelength. These compounds are a rare example of single-phase Ln hybrid materials built from molecular units that exhibit excitation-dependent photoluminescent color tuning in the solid state.
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