More Interaction Sites and Enhanced Fluorescence for Highly Sensitive Fluorescence Detection of Methamphetamine Vapor via Sidechain Terminal Functionalization of Conjugated Polymers

Abstract

A strategy of sidechain terminal functionalization was proposed to further improve the sensitivity of MA vapor detection. In this work, three fluorescent conjugated polymers (CPs) were synthesized by introducing NHBoc group at the end of the side chains and characterized by GPC, 1H NMR, FT‐IR and 19F NMR. The test results show that the introduction of the NHBoc group reduces the effect of aggregation‐caused quenching (ACQ), thereby improving the fluorescence intensity and fluorescence quantum efficiency of CPs. Secondly, it increases the interaction sites for MA capture and expands the scope of the interaction, thereby increasing the contact probability and interaction between the CPs and MA. Thirdly, the morphology of the CPs has also changed, especially the polymer containing 5‐fluoro‐2,1,3‐benzothiadiazole (1F‐2NHBoc‐CP), whose film has a network‐crosslinked porous structure, which is conducive to the enrichment and penetration of N‐methylphenethylamine (MPEA, a simulant of MA) vapor at low concentration. All these effects contribute to efficient fluorescence quenching, so the 1F‐2NHBoc‐CP can achieve more than 74% fluorescence quenching within 30 s. Taking fluorescence quenching to 1% as the detection limit, MPEA vapor with an actual concentration of 41 ppt can be detected, and its sensitivity is increased by about 25 folds relative to the NHBoc‐free counterpart polymer. Furthermore, it showed a linear correlation with MPEA vapor in the range of 41 ppt to 16 ppm, which spanned five orders of magnitude. This strategy will find a great potential in developing highly sensitive fluorescent probe for dangerous chemical vapor detection.

Approaching Tryptophan-Derived Polynorbornene Fluorescent Chemosensors: Synthesis, Characterization, and Sensing Ability for Biomedical Applications as Biomarkers for Detecting Fe2+ Ions

“…Likewise, LOD values of Poly-diester-Trp probe were substantially lower than those of Poly-monoester-Trp probe. The higher sensitivity of disubstituent polymers is considered to be owing to many interaction sites , of Trp conjugated to the norbornene backbone, which greatly supported the binding of the selective metal ions to the indole moieties. The increase in interaction sites, thereby increasing the contact probability, lead to the lower of LOD values when compared to the monosubstituted polymers.…”

Preparation of Large Conjugated Polybenzimidazole Fluorescent Materials and Their Application in Metal Ion Detection

“…Specific recognition units are introduced, such as N -containing heterocyclic compounds such as quinoline [ 22 ], imidazole [ 23 , 24 ], and carbazole [ 25 ], to provide a definite binding site for metal ion as analyte. Using the availability, strong polarization, and π–π electron transition function of the conjugate system to ensure its energy transfer or electron transfer [ 26 ], the multifunctional probe may be constructed. In addition, as an effective method to achieve fluorescence probe regulation [ 27 , 28 ], the introduction of a long alkyl chain at the end of the compound increases the spatial effect of the polymer, significantly affecting the HOMO energy level, keeping the LUMO energy level basically unchanged, increasing the band gap [ 29 ], and affecting its optical properties, which is of great research value [ 30 , 31 , 32 ].…”