Embedding an organic dye into Ti-MCM-48 for direct photocatalytic selective aerobic oxidation of sulfides driven by green light

Ti-containing mesoporous silica materials with a well-defined structure could give a clear picture of the elusive reaction pathways in photocatalysis. However, the dispersion of Ti sites usually results in their bandgaps being larger than that of TiO2, which makes the narrowing of bandgaps more challenging to construct visible light photocatalysis. Here, Ti-MCM-48 with an ordered cubic mesostructure and a homogeneous dispersion of Ti sites were successfully synthesized to embed an organic dye alizarin red S (ARS), affording a visible light photo catalyst ARS-Ti-MCM-48. The selective aerobic oxidation of sulfides into sulfoxides driven by green light over ARS-Ti-MCM-48 was accomplished directly. Notably, both electron transfer and energy transfer pathways were involved in the activation of O-2, in which the Ti sites play a crucial role. Importantly, the photobleaching was effectively alleviated by embedding ARS into the mesopores of Ti-MCM-48. Moreover, high selectivities of desired sulfoxides were favorably achieved. In general, Ti-containing porous materials could be a unique scaffold for embedding photoactive molecules to carry out selective organic transformations driven by visible light.

Automated summary

Ti-containing mesoporous silica material Ti-MCM-48 with ordered cubic mesostructure and homogeneous dispersion of Ti sites was successfully synthesized. The embedded organic dye ARS-Ti-MCM-48 exhibited excellent visible light photocatalytic performance for selective oxidation of sulfides.