Two Titanium-oxo-Clusters with Malonate and Succinate Ligands: Single-Crystal Structures and Catalytic Property

Two alkane dicarboxylates substituted titanium-oxo-clusters, Ti₆O₃(OOCCH₂COO)₂(O ⁱ Pr)₁₄ (1) and Ti₆O₃(OOCC₂H₄COO)₂(O ⁱ Pr)₁₄ (2), were successfully prepared by one step in situ solvothermal synthesis. The compounds are the first examples of only flexible alkane dicarboxylate-substituted titanium-oxo-clusters. The structures of the compounds are best described as two trinuclear oxo-Ti₃ subunits linked by a μ ₂-O bridge and two malonate or succinate ligands, forming Ti₆ clusters. A photochromic effect was observed upon irradiating the crystals, and the color of the crystals was changed from transparent to gray. Photodegradation of the methyl orange in aqueous dispersions of microcrystals of compounds 1 and 2 were carried out under UV cut white light with the assistance of H₂O₂. Compound 2 exhibited higher photocatalytic activity than 1, which might be related to the smaller angles of μ ₂-O bridge in 2.