Speciation of metal phosphonates with the assistance of weak interactions

Abstract

By employing an aromatic methyl substituted V-shaped diphosphonic acid as a ligand, a series of metal diphosphonates, namely [Cu3(HL)2(H2O)2][(H2O)2] (1), [Cu(H2L)(pyz)(H2O)2][(H2O)2] (2), [Cu(H2L)(2,2'-bipy)] (3), [Cu(H2L)(4,4'-bipy)(H2O)2] (4), [Zn(H2L)(2,2'-bipy)] (5) and [Cd(H2L)(2,2'-bipy)(H2O)][(H2O)6] (6), have been synthesized. The structural studies reveal that these compounds exhibit diverse crystal structures. The introduction of the methyl group and pyridine derived auxiliary ligands results in the formation of plenty of C-HO, C-Hπ and ππ interactions, which contribute to the crystallization of metal diphosphonates. It was found that the Zn and Cd containing compounds showed intense intraligand emissions.

Structural Tuning and Sensitization of Uranyl Phosphonates by Incorporation of Countercations into the Framework

“…The zinc ion (Zn1) is tetrahedrally coordinated by one aqua ligand and three phosphonate oxygen atoms, forming a typical tetrahedral coordination geometry. The Zn–O bond lengths are in the range of 1.748(12)–​​2.076(19) Å, which is comparable to other zinc phosphonates . The two tetra-deprotonated triphosphonate ligands adopt different coordination modes.…”

“…The Zn−O bond lengths are in the range of 1.748(12)− 2.076( 19) Å, which is comparable to other zinc phosphonates. 38 The two tetra-deprotonated triphosphonate ligands adopt different coordination modes. One is octadentate, linking to six uranyl cations and two zinc ions, whereas another one is heptadentate, linking to six uranyl cations and one zinc ion.…”