Water Compatible Conjugated Microporous Polyazulene Networks as Visible-Light Photocatalysts in Aqueous Medium

A synthetic and modification method to obtain water-compatible, visible-light-active, conjugated, microporous polyazulene networks as pure organic, highly stable, reusable, and heterogeneous photocatalysts in aqueous medium by a simple protonation method was investigated. The water compatibility and photocatalytic activity of the hydrophilic polyazulenes were demonstrated in the photoreduction reaction of Cr-VI to Cr-III for heavy-metal-contaminated waste-water treatment. Furthermore, a light-induced cascade reaction mechanism with the use of additional abundant metal cations such as Fe-III or Cu-II as co-catalysts was also described. This design strategy could offer a clean and cost-effective solution to obtain water-compatible, pure organic, photoactive polymers with a broader potential for other applications in aqueous media under sustainable and environmentally friendly conditions.