Receptor fluoride fine-tuning of fluorescent polymer probe for highly sensitive fluorescence response of methamphetamine vapor

Abstract

Methamphetamine (MA) is a highly addictive drug whose high sensitivity and selectivity of vapor fluorescence detection is still a great challenge. Fluorescent conjugated polymers are promising in high sensitivity and quick response, but the present sensitivity could not match the practical application possibly due to less efficient capture of the MA molecules. In this work, we proposed a strategy of receptor regulation for the efficient capture of MA via different number of F atom substitution. Three conjugated polymers (CPs) for MA detection were synthesized by one-step Suzuki reaction, and were characterized by GPC, FT-IR and 19F NMR. As a result, as the F content increased, the sensitivity was greatly improved. However, too high F atom content resulted in decreased fluorescence and poor sensing performance. Among them, polymer containing 5-fluoro-2,1,3-benzothiadiazole (1F-CP) showed the best sensitivity with a detection limit of ca. 1.0 ppb for N-methylphenethylamine (MPEA) vapor. Especially, we obtained a conjugated polymer with fluorescence quantum yield and interaction balance, 0F-1F-CP, which not only had a detection limit of 5.12 ppb for MPEA vapor, but also had good stability and selectivity, more importantly, it had a high quenching rate for MA vapor. Dynamic simulation of molecular interaction indicated that the interaction between CPs and MPEA was enhanced after the introduction of F atoms.