Structure elucidation and topological studies of new lanthanide-organic frameworks (UPMOFs) synthesised via solvothermal route using mixed dicarboxylate linkers of 1,4-benzenedicarboxylic acid and 4,4-oxybis benzoic acid

Abstract

The new lanthanide-organic frameworks (UPMOFs) were solvothermally synthesised using M(NO3)3·6H2O (M = La, Ce, Pr and Nd) metal salts with mixed dicarboxylate ligands namely, 1,4-benzenedicarboxylic acid (H2BDC) and 4,4-oxybis benzoic acid (H2OBA). The successful synthesis produced a series of four three-dimensional (3D) UPMOFs identified as [La(BDC)(OBA)(H2O)2].H2O (UPMOF710 (1)), [Ce(BDC)(OBA)(H2O)2].H2O (UPMOF711 (2)), [Pr(BDC)(OBA)(H2O)2].H2O (UPMOF712 (3)) and [Nd(BDC)(OBA)(H2O)2].H2O (UPMOF713 (4)). Comprehensive characterisations were performed on the newly synthesised UPMOFs, encompassing techniques such as infrared spectra (IR), powder X-ray diffraction (PXRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer-Emmet-Teller (BET) and the structural elucidation was conducted using single-crystal X-ray diffraction (SCXRD). Notably, all four 3D UPMOFs were crystallised in a monoclinic sytem with different space groups. The UPMOFs (1) had a P21/n space group while the 2–4 were crystallised in the space group of I2/a. Consequently, the 2–4 UPMOFs are classified as isostructural MOFs. Remarkably, the topological analysis unveiled a novel topology denoted as upm, which has not been observed in the realm of reticular chemistry.