A metal–organic framework assembled from Y(iii), Li(i), and terephthalate: hydrothermal synthesis, crystal structure, thermal decomposition and topological studies

Abstract

A novel metal–organic framework assembled from Y(III), Li(I), and terephthalate ligand, formulated as [LiY(BDC)₂(H₂O)·2(H₂O)] (1) (H₂BDC = terephthalic acid), has been obtained as single phase under hydrothermal conditions. The crystal structure was solved by single-crystal X-ray diffraction and the bulk was characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, and BF-STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). 1 crystallizes in monoclinic space group (P2₁/c, with a = 11.6415(7) Å, b = 16.0920(4) Å, c = 13.2243(8) Å and β = 132.23(1)°) and possesses a 3D framework with 1D trigonal channels running along the [101] direction containing water molecules. The structure of 1 is made up of unusual four-membered rings formed by edge- and vertex-shared {YO₈} and {LiO₄} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. HT-XRD reveals that 1 undergoes phase transformation upon the dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetics. Topological studies were also performed revealing that 1 has a new 2-nodal net.