Fig. 2: Ultrasound-triggered organocatalysis using (non-covalent)catalyst system.

a A schematic of catalyst release from the catalyst system via the application of ultrasound stimulus for pNPA hydrolysis to 4-nitrophenol and acetic acid in aqueous buffer at pH = 7.0. Visual colour change (colourless to yellow) is observed due to the formation of 4-nitrophenol. b Conversion of the hydrolysis reaction of pNPA in aqueous buffer (pH = 7.0) followed by UV-Vis spectroscopy in the presence of imidazole (green circle), none (black square), imidazole in alginate bead (magenta diamond), imidazole in alginate bead and ultrasound stimulus (blue triangle), and in presence of imidazole in alginate bead without ultrasound stimulus for 20 min and ultrasound stimulus was added after 20 min (navy blue star). Markers indicates the experimental data. Error bars are based on standard errors in duplicate runs. The lines are to guide the eyes. c Reaction rate constants at different condition involving (non-covalent) catalyst system.