Design of Benzocoumarin-Based Small Molecular Gelators in CN- Recognition, Oil Spill Recovery, and Dye Adsorption through Phase-Selective Gelation.

Lauryl and cholesterol carbonate-linked benzocoumarin conjugates 1 and 2 have been designed, synthesized, and successfully established as supramolecular gelators. Both show gelation in DMF-H2O (2:1, v/v), DMSO-H2O (2:1, v/v), hexane, and fuel oil such as petrol, kerosene, and diesel. The aggregation behavior is explained spectroscopically. The gels are stable and exhibit good viscoelastic properties. The storage modulus (G') in each gel is considerably higher than the loss modulus (G″). The higher value of crossover point for the gel of 1 compared to the gel of 2 demonstrates the better gelation behavior of 1 over 2 in DMF-H2O (2:1, v/v) and DMSO-H2O (2:1, v/v). FESEM images reveal a fibrous morphology with different packings. Gels are anion-responsive. DMF-H2O (2:1, v/v) gels of 1 and 2 recognize selectively CN- ion over a series of other anions involving a gel-to-gel color change. Owing to the phase-selective gelation (PSG) abilities, both 1 and 2 respond to oil spill recovery. Additionally, gelator 1 removes the cationic dye from water via phase-selective gelation.