Self-Assembly and Cascade Catalysis by a Soft-Oxometalate (SOM) System

Kousik Das; Tingting Yan; Shounik Paul; Shilun Qiu; Teng Ben; Soumyajit Roy

doi:10.3389/fchem.2020.601814

Self-Assembly and Cascade Catalysis by a Soft-Oxometalate (SOM) System

Front Chem. 2020 Nov 27:8:601814. doi: 10.3389/fchem.2020.601814. eCollection 2020.

Authors

Kousik Das¹, Tingting Yan², Shounik Paul¹, Shilun Qiu², Teng Ben², Soumyajit Roy¹

Affiliations

¹ Eco-Friendly Applied Materials Laboratory, Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, India.
² Department of Chemistry, Jilin University, Changchun, China.

Abstract

Cascade catalysis has gained importance due to its various applications. In this work, cascade catalysis was performed using a self-assembled soft-oxometalate (SOM) as a model system. At first, we synthesized an oxometalate (OM) hybrid with a polymerizable organic cation, namely tetrakis(4-aminophenyl)methane, and an OM, K₈[SiW₁₁O₃₉]. The hybrid in turn was converted into SOM in water, DMSO mixture, and characterized by different techniques, ranging from electron microscopy to DLS. The SOM state is endowed with the ability to polymerize the aniline based counter ions associated with it in the presence of UV-light. This polymerization is possible due to the presence of photocatalytic OMs (oxometalates) in the SOMs. The polymer-SOM hybrid in cascade oxidizes selectively aniline to nitrobenzene and nitrite to nitrate owing to the residual oxidizing property of the OM constituents in it. This is the first example of cascade catalysis in SOM chemistry.

Keywords: cascade catalysis; oxidation; polymerization; polyoxometalate; self-assembly.