Abstract: Absorption and excited state intramolecular proton transfer (ESIPT) fluorescence of 2’-ethylhexyl salicylate (EHS) were examined in the presence of cationic, non-ionic, and anionic surfactants. It was found that linear EHS molecule was solubilized in micelles with its flexible hydrophobic 2’-ethylhexyl chain toward the micellar core and with its rigid salicylate moiety toward the micelle-water interface. The UV absorbance of EHS was improved and intramolecular hydrogen bonding formation of EHS was favored, resulting in greatly enhanced ESIPT fluorescence. The excited EHS molecules decay via visible luminescence and non-radiative deactivation. The binding sites of EHS in micelles were explained at a molecular level in terms of molecular structures and sizes of EHS and surfactants. Dynamic fluorescence quenching and spectral measurements of ester hydrolysis of EHS provide further evidences for the binding sites of EHS in different micelles.

Key words: 2’-ethylhexyl salicylate, Solubilization in micelles, Intramolecular hydrogen bonding, Intramolecular proton transfer fluorescence, Ester hydrolysis