Polyoxometalate-Based Metal–Organic Frameworks as Visible-Light-Induced Photocatalysts

Two stable 3D polyoxometalate-based metal–organic frameworks (PMOFs), [Cu I 12 (trz) 8 (H 2 O) 2 ][α-SiW 12 O 40 ]·2H 2 O ( 1 ) and [Cu I 12 (trz) 8 Cl][α-PW 12 O 40 ] ( 2 ) (Htrz = 1- H -1,2,4-triazole) based on Keggin-type POMs were successfully obtained and fully characterized. The basic building units of the two PMOFs are [Cu I 12 (trz) 8 ], but polyoxoanion (POA) template effect leads to different structures and properties: 1 represents an interesting example that [α-SiW 12 O 40 ] 4– locate in the nine-membered Cu-trz rings through Cu···O weak interactions to form a 3D framework, whereas 2 shows a 3D structure constructed from 2D bilayer cationic network [Cu I 12 (trz) 8 Cl] 3+ and [α-PW 12 O 40 ] 3– lying in the adjacent layers via Cu···O weak interactions. PMOF 1 as unusual visible-light photocatalyst exhibit significantly enhanced photocatalytic activity under visible-light and excellent stability during the photocatalysis process for recovering and recycling, as well as photocatalytic hydrogen evolution activity.