Synthesis and photocatalytic H2 evolution properties of four titanium-oxo-clusters based on a cyclohex-3-ene-1-carboxylate ligand

Four titanium-oxo-clusters with cyclohex-3-ene-1-carboxylate (Cec) ligands, Ti6(μ2-O)2(μ3-O)2(Cec)4(OiPr)12 (PTC-91; HOiPr = isopropanol), Ti6(μ3-O)6(Cec)6(OiPr)6 (PTC-92 and PTC-93) and H2[Ti18(μ2-O)11(μ3-O)14(Cec)20(OiPr)4] (PTC-94), have been solvothermally synthesized under different conditions, respectively. These clusters with the same Cec ligand show totally different structures, and they are stable in water and other common solvents. The Ti6 clusters with different conformations are presented in PTC-91, PTC-92 and PTC-93, while PTC-94 is an unusual Ti18 cluster. The photocatalytic studies reveal that PTC-91 and PTC-94 have good H2 evolution ability.