A highly sensitive and selective turn-on fluorescence sensor for iodide detection based on newly synthesized oligopyrrole derivative and application to real samples

摘要

In this study, we have synthesized and characterized a novel oligopyrrole derivative (5-[1-(4-nitrophenyl)-1H-2-pyrrolyloxyl]-1-phenyl-1H-2-pyrrolol, NPPP) based iodide ion selective fluorescent turn-on sensor. The fluorescent iodide sensor NPPP was synthesized by oxidation reaction of N-phenyl pyrrole with Cu(II) nitrate in acetonitrile. Elemental analysis, MS-spectrometry,~1H NMR, ~(13)C NMR, FT-1R, UV-vis and fluorescence spectrum of NPPP were carried out. A characteristic NPPP fluorescence emission was observed in acetonitrile and water solutions, indicating that the probe is stable in solution and the emission of NPPP was not influenced by the water molecules. NPPP displayed extremely high sensitivity to I" with 3.5-fold fluorescence enhancement by intramolecular charge transfer (ICT) process in the water media. Responses to other anions present in the solution, such as F~-, Cl~-, Br~-, AcO~-, NO_3~-, NO_2~-, SO_4~(2-), S_2O_5~(2-), CIO_4~-, IO_4~-, IO_3~-, OH~~ and the effect of pH value on the efficiency of the sensor molecule have also been investigated. NPPP exhibits very good selectivity to iodide ions over various anions interference. Under optimal conditions, its response was linearly proportional to the concentration of I~- ions in a range from 1.0 × 10~(-7) to 6.0 × 10~(-6)mol L~(-1) with a detection limit of 9.0 × 10~(-8) mol L~(-1). The proposed method was successfully applied to the direct determination of I~- in real samples such as iodine-fortified salts.