Interaction of fatty acid-containing 9-aminoacridine derivative with surfactants and bio-surfactants: Synthesis and photophysical studies

The present work describes the synthesis and photophysical studies of two 9-aminoacridine derivatives (N-(acridine-9-yl)palmitamide (AC-PA) and N-(acridine-9-yl)acetamide (AC-ACYL)). For AC-PA and AC-ACYL, the -NH2 group of 9-aminoacridine is acylated by a long hydrophobic tail (palmitic acid, a saturated fatty acid), and a short hydrophobic tail (acetic acid), respectively. The steady-state and time-resolved fluorescence of AC-PA are sensitive towards the micellization of sodium deoxycholate and sodium cholate bile salts. Fluorescence of AC-PA is also senstive to microenviornment of different type of suffactants and is used to monitor the anionic, cationic and neutral surfactants. The critical micellar concentration determined from the fluorescene studies of AC-PA in the bile salts and surfactants are consistent with the values reported in the literatur. In contrast, steady-state and time-resolved fluorescence of AC-ACYL are insenstive to towards the micellization process of bile-salts and surfactants. The comparative study presented here shows the importance of a hydrophobic long tail, attached to a fluorophore, to make its fluorescence properties sensitive towards microenvironment and, in the process, make such molecules suitable for investigation of structure and dynamics of various organized systems.