Two dimensional (2D) molecular frameworks for rapid and selective adsorption of hazardous aromatic dyes from aqueous phase

Two dimensional molecular frameworks are designed, characterized and explored as superior materials for efficient adsorption and removal of aromatic organic pollutants from water bodies. The two molecules exhibit potential in rapid and selective dye (methylene blue) adsorption in aqueous phase through non-covalent interactions. [Display omitted] •Two 2D frameworks are designed and investigated for their adsorption capacities towards aromatic organic pollutants (dyes) in water.•The two MOFs exhibit ultimate selectivity with rapid adsorption capability for dye Methylene Blue.•The detailed kinetic studies are also performed to support the adsorption pathway.•The work also highlights the advantages of 2D microscopic sheets as excellent hazardous dye adsorbents.•Structure-activity relation is established for future course for purification of waste water. Herein, two dimensional metal organic frameworks, [M(ox)(bpy)]n [H2ox = oxalic acid, bpy = 4,4′-bipyridine and M = Cu (1) or Co(2)] are designed under solvothermal condition and characterized thoroughly by FTIR, PXRD, TGA and single crystal X-ray studies. X-ray structure along with topological analysis reveals a two dimensional (2D) framework of the present material with sql topology with metals in square bipyramidal geometry. The two MOFs are employed for adsorption of organic dyes i.e. methylene blue (MB) and methyl orange (MO) considered widely as water pollutants. Interestingly, the molecular frameworks showed selective nature towards methylene blue, the cationic dye. The framework remains stable after adsorption of dye and can be recycled up to five times. At equilibrium, the removal percentage of MB by the frameworks is ultimate (96–98%) with optimum temperature (25 °C) and pH (neutral). The kinetic studies are suggestive of the adsorption to proceed via pseudo second order reaction. The key factors or mechanism for enhanced adsorption of MB are electrostatic, π-π and hydrogen-bonding interactions existing between the 2D sheets and the dye. Thus, fine structural tuning of the easy-to-prepare two dimensional frameworks could lead to adsorb and remove the hazardous organic aromatic pollutants with high efficiency at low cost in future endeavours.