8-Hydroxyquinoline functionalized titanium-oxo clusters for visible-light-driven photocatalytic oxidative desulfurization

Abstract The 8-hydroxyquinoline functionalized titanium-oxo clusters (TOCs) of the formulation [Ti9(μ3-O)7(μ2-O)3(μ2-OiPr)(OiPr)5(O2CtBu)9(OQ)]·HOiPr (HOQ = 8-hydroxyquinoline) and [Ti12(μ3-O)8(μ2-O)6(μ2-OiPr)2(OiPr)4(O2CtBu)12(OQ)2]·4H2O were synthesized and structurally characterized by single-crystal X-ray diffraction. The assembly mode between the {Ti3(μ3-O)} and {Ti6(μ3-O)6} building units in the clusters has been rarely observed for titanium-oxo clusters. These two clusters exhibit intense visible absorption with narrow band gap of ~2.4 eV due to the presence of 8-hydroxyquinoline ligands. The clusters exhibit favorable catalytic activity for the visible-light-driven photocatalytic oxidative desulfurization (PODS) of dibenzothiophene. The results demonstrate that the core structure and functional ligands are important for the photocatalytic activity of titanium-oxo clusters.