Two highly stable inorganic-organic hybrid 3D frameworks based on Cu-Ln incorporated polyoxometalates for selective dye removal and proton conduction

Two novel inorganic-organic hybrid 3D TM-Ln incorporated POM-based frameworks, H 2 [Cu 2 OL 3 (H 2 O) 2 ][Ce(L)(H 2 O) 3 (PW 11 O 39 )]·17H 2 O ( 1 ) and H 4 [CuL 3 ] 2 [Ln(H 2 O) 3 (PW 11 O 39 )] 2 ·28H 2 O ( 2 ) (L = 4,4′-bipyridine), were hydrothermally synthesized at different temperatures. Structural analysis reveals that both compounds are constructed from [Ln(PW 11 O 39 )] 4− polyoxoanions and different copper complexes. Interestingly, in compound 1 , 2D copper complex layers and 1D chain [Ln(PW 11 O 39 )] 4− polyoxoanions interconnect to form a 3D framework. In contrast, in compound 2 , 1D copper complex chains join the 2D [Ln(PW 11 O 39 )] 4− layers to give rise to a 3D framework. Both compounds exhibit excellent chemical stability. Furthermore, the dye adsorption and proton conduction properties of both compounds were also investigated. The conductivities of 1 and 2 are 3.175 × 10 −4 S cm −1 and 1.750 × 10 −4 S cm −1 at 85 °C and 98% RH, respectively. Dye adsorption studies indicate that they can selectively adsorb cationic dyes MB, CV and BR over anionic dyes MO, AO and large cationic RhB. Two highly stable inorganic-organic hybrid 3D TM-Ln incorporated POM-based framework materials have been successfully synthesized. The compounds can not only exhibit moderate proton conductivity but also selectively adsorb cationic dyes.