The absorption spectra of Sm²⁺ doped in MFX (M=Sr, Ba; X=Cl, Br) crystals were studied within the range of 20,000–35,000 cm^−1 as a function of temperature and host. The absorption bands observed were described with a simple model developed by Wood and Kaiser using group theory. The temperature and host dependence on the ⁷F₀→⁵D₃ Fano resonance lines were investigated. BaFCl:Sm²⁺ system showed a “normalâ€� ⁷F₀→⁵D₃ transition at 4 K in spite of similar crystal structure and absorption profile with other MFX hosts. New Fano resonances were observed in the absorption spectra at higher energies (23,000–25,000 cm^−1) for all MFX:Sm²⁺ systems at 4 K which persist up to room temperature. Preliminary energy level calculation showed that these resonance lines involve the interaction between higher excited ⁵L_J states of 4 f⁶configuration and 4 f⁵5d¹ configuration.

The emission lifetime of Sm²⁺ ions doped in MFX (M=Ba, Sr; X=Br, I) crystals was investigated as a function of pressure and temperature. The decay of the ⁵D_J(J=0,1,2) levels showed single exponential relaxation. The analysis of these experiments yielded the position of the lowest 4f⁵5d¹Â state as well as non-radiative rate constants. These values were compared with those for Sm²⁺ doped in other matlockite host crystals. The single exponential decrease of the ⁵D_0,1 lifetime as a function of pressure was described considering the increased radiative decay rates of these ⁵D_0,1 levels through electronic mixing between the 4f⁵5d¹Â and ⁵D_Jstates.

The emission spectra of Sm²⁺ doped in BaFBr and SrFBr hosts were measured at 10 K from ambient pressure to 8 GPa. The crystal field energy levels determined from the emission spectra were used to extract the free ion parameters (F_k and ζ ) and crystal field parameters (B_q^k). The variation of F_k and ζ as a function of pressure was studied systematically and was discussed in relation to the central field and symmetry restricted covalency models. The change of the spin orbit coupling parameter (ζ) with pressure for SrFBr:Sm²⁺ showed very different behavior than in other matlockite hosts. Moreover the variation of B_q^k under pressure was studied. The pressure dependence of the B_q^k was described quantitatively using the Superposition Model (SM) with the help of structural parameters as a function of pressure, obtained from periodic DFT calculations. The validity of the SM was tested for Sm²⁺ in BaFBr and SrFBr. It is shown that this model does not apply to SrFBr, in contrast to other matlockite host materials.

The structure and thermodynamic properties of lanthanide complexes with a new tripodal ligand L2 have been elucidated using different physicochemical methods. At stoichiometric ratios, the tetrahedral three-dimensional complexes with lanthanide cations are formed in acetonitrile with good stabilities. Despite minor structural changes comparing to previously investigated tripodal ligands, the resulting assembly exhibits different features revealed with the crystal structure of [Eu₄L2₄](OH)(ClO₄)₁₁ (orthorhombic, Pbcn). Interestingly, the highly charged edifice contains an inner cage encapsulating a perchlorate anion. Such lanthanide mediated cage-like assemblies are rare, and may be of interest for different sensing applications. Indeed, the anionic guest can be exchanged with different anions. The related host–guest equilibria were investigated with NMR techniques. Various aspects of these reactions are qualitatively discussed.

The luminescence of Sm²⁺-doped BaFBr has been measured as a function of temperature and pressure. The ⁷F_J crystal field levels have been identified and the corresponding crystal field parameters evaluated. Temperature dependent lifetime measurements allow to locate the energy of the lowest 4f⁵5d¹ level. Pressure dependent measurements up to 8 GPa show linear red shifts of the ⁵D_2,1,0 levels. These shifts are about 3 times stronger than the well known ruby pressure shifts and highlight thus the potential use as pressure sensors below 8 GPa.

The luminescence of Sm²⁺-doped BaFBr has been measured as a function of temperature and pressure. The ⁷F_J crystal field levels have been identified and the corresponding crystal field parameters evaluated. Temperature dependent lifetime measurements allow to locate the energy of the lowest 4f⁵5d¹ level.

Pressure dependent measurements up to 8 GPa show linear red shifts of the ⁵D_2,1,0 levels. These shifts are about 3 times stronger than the well known ruby pressure shifts and highlight thus the potential use as pressure sensors below 8 GPa.