Computationally designed ionic liquid based molecularly imprinted@ graphene oxide composite: Characterization and validation

Abstract 4-Hydroxy benzoic acid (4HA), a metabolite of Paraben is an emerging contaminant (EC) commonly used as preservative in cosmetics, pharmaceuticals, personal cares products and food industries. Removing metabolite of ECs can be one of the strategies to control their harmful effect on the ecosystem. Molecularly imprinted polymers synthesized using ionic liquids (ILMIPs) @ graphene oxide (GO) composites can be effective in this regard. The present work reports Density Functional Theory (DFT) to design the said composites by selecting suitable ionic liquid (IL) as functional monomer in order to get a stable template-monomer complex (TMC) with 4HA (template), an important parameter for creating imprinted sites for higher efficiency of the said composites. Simulated library of 17 ILs were created and their TMCs with 4HA were optimized. Amongst the17 ILs, TMCs of 1-allyl-3-octylimidazolium chloride (1A3OIC) exhibited highest and 1-vinyl-3-carboxy pentylimidazolium bromide(1V3CPB) depicted intermediate change in the Gibbs free energy values with 4HA. Simulated and experimental IR spectra of 4HA, selected ILs and their TMCs were compared for the identification of the functional groups involved in the formation of TMCs through hydrogen bonding. Theoretical studies of TMCs with GO moiety helped in designing efficient composite. Insight into the chemistry was obtained by Mulliken charge analysis. Experimental studies of synthesized ILMIPs after characterization confirmed conciliation with simulated data.