Yb(C(4)H(4)O(4))(1.5)] undergoes a temperature-triggered single-crystal to single-crystal transformation. Thermal X-ray single-crystal studies showed a reversibly orchestrated rearrangement of the atoms generated by the breaking/formation of coordination bonds, in which the stoichiometry of the compound remains unchanged. The transformation occurs on heating the crystal at approximately 130 degrees C. This uncommon behavior was also studied by thermal methods, FTIR spectroscopy, and thermodiffractometry. Both polymorphs, alpha (room-temperature form) and beta (high-temperature form), are proven to be active heterogeneous catalysts; the higher catalytic activity of beta is owed to a decrease in the Yb coordination number. A mechanism based on spectroscopic evidence and involving formation of the active species Yb-O-OH is proposed for the sulfide oxidation.

A luminescent lanthanide metal-organic framework (MOF) based on Eu 3+ and Tb 3+ ions with 2-phenylsuccinate (EuTb-psa) was obtained solvothermally to explore its behavior as a temperature sensor in an unconventional temperature range through the study of the thermal evolution of the hypersensitive 4f-4f 5 D 0 → 7 F 2 transition and the luminescence lifetime. The efficiency of the luminescence process was evaluated through the europium intrinsic quantum yield (Q Eu ), and its variation as a function of temperature is also reported. The optical [a]

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Reactions in aqueous solution under hydrothermal conditions between (±)-2,3-dimethylsuccinic acid and lanthanide chlorides lead to two different isostructural types with chemical formulas [Ln2­(C6H8­O4)3­(H2O)2] Ln(III) = Pr–Eu (except Pm) (Type I, compounds 1–4) and [Ln2­(C6H8­O4)3] Ln(III) = Tb–Yb (except Tm) (Type II, compounds 5–9). The crystal structure has been solved for the Pr (1)-, Sm (3)-, and Ho (7)-containing compounds by means of single-crystal XRD methods, whereas powder XRD Rietveld refinement was used for the rest of the MOFs. Compounds 1–4 crystallize in the triclinic space group P1̅, whereas compounds 5–9 belong to the tetragonal space group P43212. Type I and II compounds are 3D frameworks consisting of chains of [LnO8­(H2O)] or [LnO8] polyhedra, respectively, linked by dimethylsuccinate anions, giving rise to I1O2 connectivity. All the compounds were characterized by X-ray diffraction, variable-temperature Fourier transform infrared spectroscopy, and thermal analysis. An exhaustive topological study was performed in comparison with other related compounds. The photoluminescent (PL) properties for compounds 3, 4, and 5 have been also explored, indicating that a metal-centered luminescent process takes place.