Epoxides hydration on CoIII(salen)-OTs encapsulated in silica nanocages modified with prehydrolyzed TMOS

• Prehydrolyzed tetramethylorthosilicate (TMOS) was used as silylation reagent for encapsulation.
• CoIII(salen)-OTs in nanocages could afford the highest TOF.
• The confinement effect of the nanoreactor has different effect on deactivation rate of CoIII(salen)-OTs and CoIII(salen)-OAC.

The silylation for reducing the pore entrance size is crucial for the success encapsulation of molecular catalysts. Herein, we reported the preparation of an efficient solid catalyst for epoxide hydration via encapsulation of CoIII(salen)-OTs in the nanocages of FDU-12 using prehydrolyzed tetramethylorthosilicate (TMOS) as silylation reagent under mild condition. CoIII(salen)-OTs in nanocages could afford TOF of 2760 h−1 in the hydration of propylene epoxide (PO), which is the highest ever reported at low PO/H2O molar ratio. Comparison of the activity of CoIII(salen)-OTs accommodated in nanocages with different microenvironments suggests that CoIII(salen)-OTs in hydrophilic microenvironment was more active than that in hydrophobic microenvironment in the hydration of propylene epoxide. Moreover, studies show that the deactivation rate of CoIII(salen)-OAc is lower than that of CoIII(salen)-OTs in nanocages due to the confinement effect of the nanoreactor.

Figure optionsDownload high-quality image (175 K)Download as PowerPoint slide