Two novel thorium organic frameworks constructed by bi-and tritopic ligands

摘要

Two thorium organic frameworks, Th(BDC)(2) and Th(OH)(BCPBA) have been hydrothermally synthesized using 1,4-benzenedicarboxylic acid (H2BDC) and 3,5-bi(4-carboxyphenoxy) benzoic acid (H(3)BCPBA), respectively. The obtained two compounds were determined by single-crystal XRD, and they exhibited two new topologies. Th(BDC)(2) shows a 3-dimensional (4,4,8)-connected framework with the Schlafli symbol of (4(14) . 6(12) . 8(2)) (4(2) . 6(3) . 8)(4(4) . 6(2)), and it is a mononuclear thorium(IV) complex. Th(OH)(BCPBA) possesses a (4,6)-connected topology with the Schlafli symbol of (4(15)) 2(4(6))(3), and it has a dinuclear thorium(IV) asymmetric unit with the shortest Th-Th distances. Viewing along suitable directions, channels with different shapes can be found in the obtained two frameworks. Based on calculation with PLATON, the amount of void space is 21.9% and 13.5% in Th(BDC)(2) and Th(OH)(BCPBA), respectively. Density functional theory (DFT) studies revealed that the metal-ligand interactions were mainly of ionic character in both compounds and the hydroxyl ions might play an important role in the stability of dinuclear thorium(IV) of Th(OH)(BCPBA).