Nanoarchitectured Graphene Organic Frameworks with High Iodine Uptake and Antibacterial Activity

In the present study, a graphene organic framework (GOF-LS) was successfully prepared by cross-linking nanosheets of graphene oxide (GO) with dimethyl-4,4′-(methylenebis (2-thioxo-2,3-dihydro-1H-imidazole-3,1-diyl)) dibutyrate (LS) as a pillaring agent via a transesterification process. GOF-LS have been characterized by various analyses, such as Fourier transform infrared, BET, powder X-ray diffraction, energy-dispersive X-ray, thermogravimetric analysis, and FE-SEM. The oxygenic functional groups in GO and the sulfur atoms of LS give mesoporous GOF-LS a strong affinity for iodine molecules due to the formation of charge-transfer complexes between the host framework's sulfur and oxygen atoms and the guest iodine molecules. Therefore, GOF-LS exhibited a high adsorption capacity of 1315.105 mg/g for removing iodine from the iodine/cyclohexane solution. In addition, GOF-LS also displayed extraordinary stability toward iodine, with an excellent capacity of 232 wt % for volatile iodine. To the best of our knowledge, this is the first report aiming at iodine uptake with a GOF built on a thioamide-based ligand. This study also aimed to investigate the antibacterial properties of GOF-LS. The antibacterial activity of GOF-L suspensions (80 μg/mL) was tested against four species of bacteria, including two Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and two Gram-positive (Bacillus subtilis, Staphylococcus aureus). The results indicated that the GOF-LS were effective against all bacterial species, with especially remarkable growth inhibition against Gram-positive bacteria. In addition, GOF-LS demonstrated promising results in controlling antibiotic-resistant strains of E. coli and S. aureus in the environment. This study will contribute to the development of a cost-effective, metal-free, stable, and environmentally friendly multifunctional framework for the remediation of iodine-containing pollutants and the control of bacterial infections, addressing critical needs in environmental protection and public health.