Synthetic investigation, structural analysis and photocatalytic study of a carboxylate–phosphonate bridged Ti18-oxo cluster

Abstract

By the combination of carboxylate and phosphonate ligands, we herein report a nanosized H₂[Ti₁₈(μ₃-O)₁₄(μ₂-O)₆(O₃P-Phen)₂(PA)₁₆(OPri)₁₄] (PTC-51) (HPA = propionic acid, O₃P-Phen = phenyl phosphonate), whose structure can be observed as the linkage of independent phosphonate supporting and carboxylate bridging hexanuclear Ti(IV) clusters. We also demonstrate a concise crystalline phase diagram, which shows the important effect of phosphonate and carboxylate ligand ratio during synthetic reactions. The photocatalytic H₂ evolution activities of the obtained polyoxotitanate materials have been studied, with carboxylate-Ti₆ presenting the maximum H₂ production rate up to 267.78 μmol g⁻¹ h⁻¹.