Cooperative integration of Keggin-type polyoxometalate and zirconium-based molecular cage into a crystalline porous ionic salt for efficient photoreduction of hexavalent chromium

In current work, amino-functionalized zirconium-based tetrahedral cage (ZrT-1-NH 2 ) and anionic Keggin-type polyoxometalate {SiW 12 }, driven synergistically by electrostatic forces and hydrogen bonding interactions, ultimately self-assembled into an unusual porous crystalline ionic salt (denoted as ZrTNH 2 -SiW 12 ) with photocatalytic activity. When applied in the photocatalytic reduction of hexavalent chromium (Cr(VI)), the generated reactive superoxide radical anions (·O 2 - ) significantly enhance the reduction process, achieving nearly complete removal (>99 %) within 90 min. Experimental results demonstrate that The reduction efficiency of Cr(VI) almost reached 100 % within 90 min of illumination. Indeed, combining the cationic molecular cages with the anionic POMs to yield porous solids that exhibit multifunctional properties represents a promising avenue of research, and will promote collaborative development.