Trapped Cyclic Dimeric Oxyanion Assembly by a Urea- Functionalized Receptor: Potent Application in Linear Discriminant Analysis and as Antibacterial Agents

The naphthalimide-based linear monourea receptors L-1 and L-2 exhibit anion (oxyanions and halides) binding in the solid and solution states. The receptor L-1 could render fluoride-/hydroxide-induced aerial CO2 fixation efficiently, leading to air-stable assembling of dianions enclosed by n-TBA cations via the formation of an R-2(2)(8)-type cylindrical dimeric arrangement. The assembly of the anions is stabilized via short-range hydrogen-bonding interactions. A cyclic dimeric assembly of bisulfate anions sealed by the linear tetrameric assembly of the host molecule was also evidenced from the solid-state architecture. Upon addition of excess amounts of chloride and bromide anion, linearly assembled L-1 captured a cyclic chloride-water and bromide-water tetrameric cluster. The ligands were capable of discriminating five relevant anions with 100% classification accuracy in aqueous media on the basis of multivariate pattern analysis. Interestingly, the ligands L-1 and L-2 displayed notable bactericidal activity against the Gram-negative pathogen E. coli MTCC 433 and were nontoxic to cultured human embryonic kidney (HEK 293) cells.

Automated summary

Naphthalimide-based linear monourea receptors L-1 and L-2 can bind oxyanions and halide ions in both solid and solution states. Receptor L-1 efficiently fixes airborne CO2 induced by fluoride/hydroxide, forming air-stable dianions enclosed by n-TBA cations. Ligands L-1 and L-2 demonstrate bactericidal activity against E. coli MTCC 433 and are non-toxic to HEK 293 cells.