Interconversion of lanthanide-organic frameworks based on the anions of 2,5-dihydroxyterephthalic acid as connectors

Abstract

The dependence of the nature of the MOF from the synthetic conditions have been here faced studying the reaction of suitable lanthanide precursors with 2,5-dihydroxyterephtalic acid (H 4 L). The interconversion between different lanthanide derivatives having [H 2 L] 2and [L] 4as anionic spacers was observed. The known gadolinium coordination polymer (CP) {[Gd 2 (H 2 L) 3 (DMF) 4 ] . 2DMF} n (DMF = N,N-dimethylformamide), 1, was prepared in DMF, either at 90 °C or also at room temperature, if assisted by a base diffusion. NMR monitoring for the synthesis of the analogous yttrium system (DMF, 90 °C) showed that the reaction progress relates with the formation of NHMe 2 by DMF decomposition. {[Y 2 (H 2 L) 3 (DMF) 4 ] . 2DMF} n , 2, isotypic with 1, was obtained. The new structurally characterized CP {[Gd 2 (H 2 L) 3 (H 2 O) 6 ] • 2H 2 O} n 3, has been prepared by initial thermal (T = 170 °C) desolvation of 1 in vacuo (P = 1 . 10 -3 Torr), followed by a hydrothermal treatment. Interestingly, 3 reverted back to 1 by treatment in DMF at 90°C. Moreover 3 has been obtained starting from the metal nitrate and H 4 L in hydrothermal conditions (140 °C; 12h) in the presence of the stoichiometric amount of NaOH. Long reaction times produced the intermediate formation of a mixture where it was possible to identify the new structurally characterized {[Gd 2 (H 2 L) 3 ] . 2 H 2 O} n , 4, the known {[Gd 2 (H 2 L) 2 (L) 0.5 (H 2 O) 3 ] • 4H 2 O} n , 5 and {[Gd 2 (H 2 L)(L)(H 2 O) 5 ] • 2H 2 O} n , 6, while at higher temperature (160 °C; 24h) the pure 6 was obtained. The observed transformations of 1 into 6 in H 2 O involve H 4 L elimination. On the other hand, it was found that the treatment of 6 in DMF in the presence of H 4 L leads back to 1. Single Crystal X Ray Diffraction (SCXRD) studies were carried out on the new species 2, 3 and 4.

Rationally Reconstructed Metal–Organic Frameworks as Robust Oxygen Evolution Electrocatalysts

“…[15][16][17] As shown in Figure 1a and Figure S1, H 4 DOBDC have two carboxylic groups rigidly located at an angle of 180° (1,4-benzenedicarboxylic acid functionalities) and two phenolic functional groups. 18,19 Deprotonation of H 4 DOBDC can form two kinds of ligand anions: 2,5-dihydroxyterephthalato anion ([H 2 DOBDC] 2− ) with the pKa value of 7.31 and 2,5-dioxidoterephthalato tetra-anion ([DOBDC] 4− ) with the pKa value of 26.67. 20,21 Alkaline environment can be formed spontaneously through the solvothermal decomposition, even if base is absent from the starting reagents.…”

Exploring metal carbamates as precursors for the synthesis of metal–organic frameworks

“…methylformamide) at 90 °C for 12 h or a longer reaction time (1 month) at room temperature. 28 Recently, the use of piperazine dicarbamate as the linker in combination with a Zn II salt to afford a MOF with the same connectivity as MOF-5 has been reported in the literature. 29 Herein, we report on the syntheses of two benchmark MOFs, namely, Cu II -based HKUST-1 and Zr IV -based UiO-66, using Cu II -N,N-diethylcarbamate, Cu 2 (O 2 CNEt 2 ) 4 •2NHEt 2 , as the preformed SBU for the former and Zr(IV) N,N-diethyl-carbamate, Zr(O 2 CNEt 2 ) 4 , as the metal precursor for the oxohydroxide clusters of the latter upon partial hydrolysis.…”

“…Despite this, to the best of our knowledge, the only example reported of the employment of metal carbamates as precursors for the synthesis of MOFs is the synthesis of [Gd 2 (H 2 L) 3 (DMF) 4 ]·2DMF from [Gd(O 2 CNBu 2 ) 3 ] (H 2 L 2 − = 2,5-dihydroxyterephthalate dianion; DMF = N , N -dimethylformamide) at 90 °C for 12 h or a longer reaction time (1 month) at room temperature. 28 Recently, the use of piperazine dicarbamate as the linker in combination with a Zn II salt to afford a MOF with the same connectivity as MOF-5 has been reported in the literature. 29…”

A 12-Connected [Y4((μ3-OH)4]8+ Cluster-Based Luminescent Metal-Organic Framework for Selective Turn-on Detection of F− in H2O

“…The design and the synthesis of macropore open metal-organic frameworks (MOFs) or coordination polymers (CPs) based on metal centres or clusters are of great interest for their promising potential applications in several different fields as for example in gas storage and separation, host–guest chemistry, catalysis, and fluorescence sensing [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Current interest is mainly devoted to the construction of metal–organic frameworks (MOFs) or coordination polymers (CPs) through coordination of metal ions with multifunctional organic ligands as connectors [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. LnMOFs (MOFs based on trivalent lanthanides) containing dicarboxylate linkers show an intriguing variety of crystal structures and topologies due to their usually high coordination number leading to cluster units and polymeric chains most frequently observed for these compounds.…”