A Metal‐Organic Framework Incorporating Eight Different Size Rare‐Earth Metal Elements: Toward Multifunctionality À La Carte

Abstract

Multi‐metallic multivariate (MTV) rare earth (RE) metal−organic frameworks (MOFs) are of interest for the development of multifunctional materials, however examples with more than three RE cations are rare and obstructed by compositional segregation during synthesis. Herein, this work demonstrates the synthesis of a multi‐metallic MTV RE MOF incorporating two, four, six, or eight different RE ions with different sizes and in nearly equimolar amounts and no compositional segregation. The MOFs are formed by a combination of RE cations (La, Ce, Eu, Gd, Tb, Dy, Y, and Yb) and a 1,7‐di(4‐carboxyphenyl)‐1,7‐dicarba‐closo‐dodecaborane (mCB‐L) linker. The steric bulkiness and acidity of mCB‐L is crucial for the incorporation of different size RE ions into the MOF structure. Demonstration of the incorporation of all RE cations is performed via compositional and structural characterization. The more complex MTV MOF, including all eight RE ions (mCB‐8RE), are also characterized using optical, thermal, and magnetic techniques. Element‐selective X‐ray absorption spectroscopy and X‐ray Magnetic Circular Dichroism measurements allow us to characterize spectroscopically each of the eight RE ions and determine their magnetic moments. This work paves the way for the investigation of MTV MOFs with the possibility to combine RE ions à la carte for diverse applications.

Rationalizing the carborane versus phenyl-driven luminescence in related dicarboxylic ligands and their antenna effect for their Eu3+ and Tb3+ metal–organic frameworks: a combined experimental and computational study

“…S5, ESI†). Infrared spectra (IR) and powder X-ray diffraction (PXRD) for TDCA- Eu and TDCA- Tb match well with the reported for TDCA- Ce 64 and proved to be isostructural (Fig. S5 and S6, ESI†, respectively).…”

“…Although the 3D structures of the latter differ to those for the carborane based MOF family, they all consist of 1D rod-shaped LnOx polyhedral, with carboxylate linkers coordinating in a bridging mode. 64 The optical properties of TDCA- Ln (Ln = Eu, Tb) were investigated by measuring their UV-vis absorption (Fig. S1, ESI†) and emission spectra (Fig.…”

Magnetic properties and magnetocaloric effect of Ln = Dy, Tb carborane-based metal–organic frameworks

“…84 Synthesis of {[(Ln) 3 ( m CB-L) 4 (NO 3 )(DMF) n ]·Solv} ( m CB-Ln , where Ln = Dy or Tb ) was performed as previously described. 12,66 In a typical preparation, m CB-L (0.03 mmol) and Ln(NO 3 ) 3 (0.02 mmol; Ln = Dy or Tb) were added to a mixture of DMF (0.5 mL)/methanol (1.5 mL)/H 2 O (0.3 mL) and sonicated until complete dissolution of all reagents. The above mixture was transferred to an 8-dram vial and heated at 95 °C in an oven for 48 h. Needle-like white crystals were collected and washed with DMF.…”

“…In the last few years, we have demonstrated the efficacy of carborane-based linkers to synthesize a variety of functional MOFs. 12,63–65,66–73 Icosahedral carboranes are a class of commercially available and exceptionally stable boron-rich clusters, 74–76 possessing an unusual electronic structure, which is often highlighted by considering carboranes as inorganic 3D “aromatic” analogs of arenes. 74–76 They have high hydrophobicity, 77–83 allowing the preparation of water-stable MOFs.…”

“…Recently, we reported the successful synthesis and optical properties of {[(Ln) 3 ( m CB-L) 4 (NO 3 )(DMF) n ]·Solv} (Ln = Eu, Tb, Eu/Tb), 12 using the carborane linker m CB-L = 1,7-di(4-carboxyphenyl)-1,7-dicarba- closo -dodecaborane. Moreover, we demonstrated the possibility of synthesizing multi-metallic MOFs incorporating up to eight different sized rare-earth cations, 66 leveraging the steric bulkiness and acidity of the m CB-L ligand. This milestone opens the way for the development of multifunctional multi-Ln MOF materials with tailored properties.…”