On the Structure of Layered Double Hydroxides Intercalated with Titanium Tartrate Complex for Catalytic Asymmetric Sulfoxidation

Titanium tartrate complex has been intercalated within the gallery spaces of M-II/Al layered double hydroxides (LDHS) (M-H = Mg2+, Zn2+, Co2+) by ion exchange using CO32+ LDHs as precusors. It is found that the intercalation hardly influences the coordination number of the titanium center while making tiny perturbation on the average Ti center dot center dot center dot O distances and octahedral symmetry. The complex anions are arranged in the interlayer gallery in an interdigitated bilayer with the coordinated carboxylates pointing to the brucite-like layer and the alkoxy group adjacent to the equivalent in another complex through hydrophobic interaction. The arrangement of interlayer titanium tartrate complex has been modulated by adjusting the charge density of unit brucite-like layer and the charge occupancy of the interlayer Ti(IV)TA, anions. The intercalated structure is not collapsed until 573 K in the thermal treatment. The composition of the brucitc-like layer as host hardly influences the bilayer arrangement of interlayer complex anions as guests; however, it buts an impact on the host-guest interaction. Titanium tartrate complex intercalated LDH is were then applied is the catalysts for asymmetric oxidation of methyl phenyl sulfide. The structures of titanium tartrate intercalated LDHs were found to be stable enough to endure catalytic sulfoxidation.