Design, Synthesis, and Characterization of Polyoxotungstate-Decorated Ionic Liquid-Based Hybrid Material, [BmIm]4[SiW12O40] toward Rapid Adsorption of Dye and Antibacterial Activities.

A multifunctional polyoxometalate-ionic liquid (POM-IL)-based hybrid material comprising silicotungstic acid, [BmIm]4[SiW12O40], has been synthesized and demonstrated its efficiency toward methylene blue removal and as an antibacterial agent. Single-crystal XRD analysis confirms that the material crystallizes in monoclinic symmetry (SG: Pn), with lattice parameters a = 13.1396(5) Å, b = 16.9655(8) Å, c = 14.3493(7) Å, and Z = 2. The structure comprises a single polyanionic [SiW12O40]4- moiety surrounded by four cationic [BmIm]+ units of two different conformations, which supported DFT and Hirshfeld surface analysis. The material shows excellent removal efficiency for methylene blue, with a maximum adsorption capacity of 92.47 mg/g and 83.05% reusability after five cycles. On the contrary, FTIR and ζ-potential analyses confirm that electrostatic interactions are the predominant factors governing the adsorption process. The material also acts as a superior antibacterial agent against the opportunistic pathogens Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli with a MIC of 500-700 μg/mL. However, a comparative assessment showed that the material was more effective against P. aeruginosa compared to the other two pathogens. PXRD analysis confirms the phase purity, and FESEM and TEM analyses exhibit block-shaped morphology with particle sizes ∼2-3 μm.