Self‐Healable Metallogels for Selective Dye Adsorption

Abstract

AbstractThe low molecular weight gelator, disodium L‐(3,5‐di‐tert‐butyl‐2‐hydroxy‐benzyl)amino aspartic acid (Na2HL), has been used to prepare three metal‐organic hydrogels (metallogel) with the metal ions Ni2+ (MOG 1), Co2+ (MOG 2), and VO2+ (MOG 3). The gels have been prepared by mixing the aqueous solutions (0.5 mL) of the Na2HL(0.01 to 0.05 mmol) and M(CH3COO)2⋅4H2O {M=Ni or Co} or VO(SO)4⋅H2O (0.01 to 0.05 mmol). The gels have been characterized by IR spectroscopic studies, MALDI TOF spectrometry and various microscopic studies. All the gels are multi‐responsive in nature to different external stimuli, and among them, MOG 1 and MOG‐2 show the self‐healable property indicating a strong metal‐ligand interaction and hydrogen bonding interactions in the gel network. The thixotropic behavior and viscoelastic nature of the self‐healable metallogels have been confirmed by time dependent step‐strain experiment at room temperature. It was observed that MOG 1 shows rapid and more efficient selective dye adsorption of cationic dyes, rhodamine B (RhB) {61.7 mg g−1}, and malachite green (MG) {15.3 mg g−1} from mixtures of cationic, anionic dyes, and neutral dyes. MOG 2 also selectively adsorb cationic dyes from the mixture of dyes. The gel, MOG 3, selectively degrades fluorescein (FL) dye.