Synthesis of titanium-oxo macrocyles and their catalytic properties for oxidative desulfurization.

Two macrocyclic titanium-oxo clusters, namely, [Ti32(μ3-O)8(μ2-O)8(OCH2CH2O)32(OCH2CH2OH)16(BTA)16]·44H2O (BTA = butyrate) and [Ti32(μ3-O)8(μ2-O)8(OCH2CH2O)32(OCH2CH2OH)16(DMBTA)16(HDMBTA)2]·24H2O (DMBTA = 2,2-dimethylbutyrate) were synthesized and structurally characterized. The framework of the Ti32-oxo macrocycle was cyclically fixed by the double-deprotonated ethylene glycolate ligands, which exhibit an inner cavity of about 1.2 × 1.2 nm. The catalytic properties of the Ti32-oxo macrocycles towards the oxidative desulfurization (ODS) reaction were investigated. The structure-dependent catalytic properties towards oxidative desulfurization were observed for the Ti32-oxo macrocycles functionalized with the different carboxylate ligands.