Non-traditional intrinsic luminescence of amphiphilic-based ionic liquids from oxazolidines: Interaction studies in phosphatidylcholine-composed liposomes and BSA optical sensing in solution

摘要

This study presents the synthesis in good overall yields of oxazolidine-based ionic compounds obtained from protected t-serine followed by an esterification reaction with bromoalcohols and a reaction with 1-methylimidazole in acetonitrile under reflux. These compounds present in ethanol solution an absorption maxima located around 210 nm, resulting in a non-traditional intrinsic luminescence observed between 350 and 390 nm. According to calculations performed at CAM-B3LYP/6-311++G(d,p), these redshifted emission bands would be related to the increased polarity of these structures (mu > 10 D). Fluorescence titration experiments were also performed, and the partition coefficient in PC liposomes was determined, presenting high values (K-p similar to 10(4)). In addition, their interaction with bovine serum albumin (BSA) in a phosphate buffer solution (PBS) was investigated, presenting a suppression mechanism where the imidazolium seems to playa fundamental role. Docking simulations were also performed to better understand the observed BSA suppression mechanism upon the addition of oxazolidines. (C) 2020 Elsevier B.V. All rights reserved.