Dual Molecular Oxygen Activation Sites on Conjugated Microporous Polymers for Enhanced Photocatalytic Formation of Benzothiazoles

Oxidative formation of high value compounds involving active oxygen species using heterogeneous polymeric photocatalysts has become a useful tool in catalysis. Controlling the interaction between the active sites on polymer photocatalysts and oxygen molecules is still challenging due to the rather large polymer backbone structure. Here, we design a triazine-containing donor acceptor-type conjugated microporous polymer (CMP) containing dual major active sites at F and N atoms for molecular oxygen activation. Introducing fluorine atoms on the CMP backbone led to a combined effect of enhanced adsorption and electron transfer of oxygen. Time-resolved photoluminescence, electronic paramagnetic resonance spectra, and DFT calculation revealed favorable absorption energy and electron transfer kinetics between the CMP and oxygen molecules, thus efficiently generating superoxide radicals (O2 center dot-) and singlet oxygen (1O2) as main active oxygen species. The photocatalytic activity, selectivity, and reusability of the CMP was demonstrated by the photocatalytic formation of a variety of benzothiazoles.

Automated summary

The oxidative formation of high value compounds using heterogeneous polymeric photocatalysts has become a valuable tool in catalysis. However, controlling the interaction between the active sites and oxygen molecules is challenging due to the large polymer backbone structure. In this study, a triazine-containing conjugated microporous polymer (CMP) with dual active sites was designed for molecular oxygen activation. Introducing fluorine atoms on the CMP backbone enhanced the adsorption and electron transfer of oxygen, efficiently generating superoxide radicals and singlet oxygen as active oxygen species. The photocatalytic activity, selectivity, and reusability of the CMP were demonstrated by the formation of benzothiazoles.