Two Sets of Metal Organic Frameworks along the Lanthanide Series Constructed by 2,3-Dimethylsuccinate: Structures, Topologies, and Strong Emission without Ligand Sensitization

Abstract

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.

Insight into the Metal Content–Structure–Property Relationship in Lanthanide Metal–Organic Frameworks: Optical Studies, Magnetism, and Catalytic Performance

“…The presence of two bands ascribed to the hypersensitive 4 I 9/2 → 2 P 1/2 transition suggests the existence of two active neodymium centers, in coincidence with the crystallographic data. [9a] This fact is also supported by the thermal evolution of the transition when the temperature increases from 25 to 150 K. As shown in Figure S5 the intensity of the multiplet located at 429 nm decreases by 41 % when the temperature reaches 150 K, while that of the corresponding one at 430.5 nm increases by 43 %.…”

“…According to the crystallographic data,[9a] under identical synthesis conditions, two families of compounds were obtained: one belonging to the triclinic space group P 1 with formula [Ln 2 (2,3‐dms) 3 (H 2 O) 2 ] (Ln = Nd–Eu, Ln‐dms‐1 ), and the other in the tetragonal space group P 4 3 2 1 2 [Ln 2 (2,3‐dms) 3 ] (Ln = Tb–Yb, Ln‐dms‐2 ). There are two crystallographically nonequivalent lanthanide atoms in the primary building unit (PBU) of Ln‐dms‐1 .…”

“…During the last decades, metal–organic frameworks (MOFs) have been the focus of interest because of their potential applications in catalysis, ion exchange and chemical separation, drug delivery, luminescence, and magnetism, which make them promising multifunctional materials for emerging devices . In particular, these studies have addressed the synthesis of new MOF architectures with mechanical,, optical, catalytic, thermal,, chemical, sensing and magnetic, or antibacterial properties, and their structure–property relationships were explored. The synthesis and structural characterization of flexible ligand‐based coordination polymers with multifunctional properties is an important topic in our group.…”

“…With the aim to extend our studies on lanthanide–succinate MOFs, the use of 2,3‐dms, 2‐methylsuccinate, and 2‐phenylsuccinate ligands was investigated to assess the impact of the conformational flexibility of the aliphatic subunits and the coordination‐geometry preferences on the frameworks. A set of dense Ln‐MOFs obtained by us and their corresponding structural and topological features are shown in Figure : Ln‐dms‐1 [9a] (Ln = Nd, Pr, Sm, Eu), Ln‐dms‐2 [9a] (Ln = Tb, Dy, Ho, Er, Yb) (dms = 2,3‐dimethylsuccinate), Ln‐psa [9b], (Ln = Nd, Pr, Eu, Sm, Gd, EuTb, EuGd) (psa = 2‐phenylsuccinate), and Ln‐msuc [14a] (Ln = Nd, Dy, Eu, Gd, Tb) (msuc = 2‐methylsuccinate).…”

Flexible Ligand‐Based Lanthanide Three‐Dimensional Metal–Organic Frameworks with Tunable Solid‐State Photoluminescence and OH‐Solvent‐Sensing Properties

“…The color emission of Sm‐msucc , Eu‐msucc , Gd‐msucc , and Tb‐msucc were quantified in terms of the x , y color coordinates, as displayed in Figure . Except for Gd‐msucc , the remaining MOFs present lanthanide‐centered luminescence without ligand sensitization; for this reason, the x , y coordinates are close to those of MOFs such as Ln‐2,3‐dms and Ln‐psa (see Section S12). Section S13 in the Supporting Information summarizes the SSPL in the visible range of various succinate‐type frameworks.…”