Nanoarchitectonics with Positionally Isomeric Coumarin Carbamates: Structure-Gelation Study, F- Recognition, Dye Removal and Excellent Oil-Spill Recovery

Coumarin carbamates with cholesteryl group 1 and 2 have been designed, synthesized and characterized. The isomeric compounds show different gelation behaviors in organic solvents such as toluene and CH3CN. Rheological studies reveal the different viscoelastic properties of the gels. Gels of the isomers differ in morphology. While an intertwined fibre-like structure is noted for the toluene gel of 1, rod like fibres are observed for toluene gel of 2. The positional alteration of carbamate group around coumarin changes the polarity of the isomers and hence influences the packing of molecules to establish different 3D networks for gel formation as explained by DFT study. Gels of the isomers show multiple applications with different attributes. Toluene gel of 1 is found to be F--responsive and undergoes gel-to-sol phase transition due to the disruption of intermolecular hydrogen bonding through deprotonation. Under the condition, toluene gel of 2 is anion stable. Compound 1 also shows measurable interaction with F- over other anions in CH3CN as interpreted by UV-vis and emission spectral changes. Based on phase-selective gelation (PSG) property, both 1 and 2 is deployed to remove cationic dye from water. Further, only gelator 2 is useful for oil spill recovery, whereas isomer 1 is not suitable in this regard.