A 1D anionic lanthanide coordination polymer as an adsorbent material for the selective uptake of cationic dyes from aqueous solutions

A 1D anionic lanthanide coordination polymer {[(CH₃)₂NH₂] [(H₂abtc)₂Ho(H₂O)]}_n (1) (H₄abtc = 3,3′,5,5′-azobenzene-tetracarboxylic acid) has been synthesized under hydrothermal reaction conditions. The protonated [(CH₃)₂NH₂]⁺ is generated from decomposed DMA during the reaction, and balances the negative charge of the framework. The as-obtained samples were characterized using single-crystal and powder X-ray diffraction and TGA. Interestingly, 1 can selectively capture cationic dye molecules from mixtures of dye molecules containing different charges in aqueous solutions. Furthermore, 1 exhibits a different adsorption efficiency toward different cationic dyes (crystal violet, rhodamine B, safranine T and methylene blue). Among the studied dyes, methylene blue has a higher adsorption efficiency in comparison to the others. Thus, complex 1 could serve as a good candidate material for the selective removal of cationic dyes during the treatment of wastewater.