A bis-pyrene polyamine receptor for fast optical detection of ketoprofen: synthesis, characterization and application in all-solid-state fluorescent sensors†

Herein, we report on a polyamine receptor L1 bearing pyrene fluorogenic groups for the optical assessment of the non-opioid analgesic drug ketoprofen (KP). L1, composed of a diethylenetriamine moiety linked at its extremities to the 1 position of two pyrene units via methylene linkers, produced an emission at 460 nm in 1 : 1 (v/v) water/ethanol mixture at pH 7, which can be attributed to the excimer formation between the two aromatic groups. In the presence of KP, a salt-bridging interaction between the carboxylate group of the analyte and the central ammonium group of L1 induced a redistribution of acidic protons in the polyamine chain, causing a marked increase in the emission. This optical signal was used to detect KP in aqueous media. Based on this observation, the properties of all-solid-state optodes with plasticized PVC membranes doped with L1 and deposited on an appropriate solid support material were further investigated. The best membrane contained 1 wt% of fully protonated L1, plasticized with DOS and doped with 3 equiv. of the TDMACl anion-exchanger, which detected KP in the 2 μM–0.1 mM range with a low influence of interfering ions. Furthermore, this membrane was applied for the assessment of the amount of KP in OkiTask, achieving an RSD of 2.1% and recovery of 102%. Moreover, the possibility to decrease the LOD of KP to 0.84 μM (0.21 mg L⁻¹) through the application of L1-based fluorescent sensor arrays and chemometrics was studied.