A stable N-containing heterocyclic carboxylic acid ligand Co-MOF for photoelectric performance and anionic dyes adsorption.

Metal-organic frameworks (MOFs) are crystalline porous hybrid materials with periodic network structure and abundant active sites, which are promising adsorbents for organic pollutants. Herein, a novel Co(II)-based organic framework (Co-MOF) [Co 2 (L 1) 2 (L 2)] (L 1 = 3-(3-carboxylphenyl) isonicotinic acid, L 2 = 4, 4′-Azopyridin) was developed for selective dyes adsorption. Experiments suggest that the Co-MOF exhibits high stability, good photoelectricity and high selectivity for dyes adsorption. For dyes adsorption, the Co-MOF shows a strong adsorption to methyl orange achieving a high capacity up to 440.5 mg g⁻¹, but shows a weak adsorption to methylene blue or rhodamine, indicating its better selectivity for anionic dyes. An insight into the selective removal of the methyl orange is being accounted for by acid-base attraction, anion-π and π–π stacking interactions, involving the Co ion, phenyl rings, and ocarboxylate of L, and the phenyl rings, and osulfonate of MO. The current work contributes to the development of future multifunctional MOF materials with the application in environment protection. [ABSTRACT FROM AUTHOR]