Pyrene Substituted Phthalonitrile Derivative As a Fluorescent Sensor For Detection of Fe3+ Ions in Solutions.

In this current study, the novel bis[4,5-(pyrene-2-yl)-3,6-(hexyloxy)] phthalonitrile (SPN) fluorophore has been successfully synthesized. Structural characterization of this novel compound was performed by different spectroscopic methods such as FT-IR, MALDI-TOF, 1H-NMR, 13C-NMR and elemental analyses as well. In addition, the photophysical properties were determined using UV-vis absorption, steady-state fluorescence, time-resolved fluorescence spectroscopic methods and quantum chemical calculations. The metal sensing behavior of the SPN was determined in the presence of various metals (Li+, Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Fe3+, Cr3+, Co2+, Ni2+, Ag+, Cd2+, Al3+, Hg+ and Zn2+) using fluorescence spectroscopy. The novel pyrene based phthalonitrile (SPN) showed high sensitivity and selectivity towards Fe3+ ion over other examined metal ions. In order to perform the determination of Fe3+ ion in environmental samples, experimental conditions such as selectivity, stability, precision, sensitivity, accuracy and recovery were optimized. Also, the complex stoichiometry of the novel pyrene based phthalonitrile (SPN) and Fe3+ ions was determined by a Job's plot. The compound was also studied via density functional theory calculations revealing the interaction mechanism of the molecule with Fe3+ ions.

A novel polymeric fluorescence sensor based on acrylated citric acid for detection of melamine adulteration: Application in milk powder.

Melamine selective acrylate citric acid (ACA) based polymeric membrane sensor was prepared by radical polymerization method and the sensor was characterized. The sensor showed a selective fluorescent response to melamine (λex/λem = 388/425 nm). The sensor response is linear in the concentration range of 3.96 × 10-9 to 7.93 × 10-8 mol L-1, the optimum pH value is 6.0 and response time is less than 1 min. Limit of detection (LOD) and limit of quantification (LOQ) were calculated as 2.32 × 10-10 mol L-1 and as 7.74 × 10-10 mol L-1, respectively. The sensor showed great selectivity towards melamine in the presence of a large number of molecules and ions. The performance of sensor was also confirmed by determining of melamine in milk powder sample and the results were compared with HPLC results and acceptable results were obtained. As a conclusion, the results revealed that the proposed sensor is an interesting alternative for melamine determination.

Reusable fluorescent photocrosslinked polymeric sensor for determining lead ions in aqueous media.

In this study, 1-vinylimidazole units bearing photocured films were prepared as fluorescent sensors towards Pb(2+) in aqueous solutions. The influence of experimental parameters such as pH, time and foreign ion concentrations were investigated. Sensor response was linear over a concentration range of 4.83×10(-8) to 4.83×10(-7) mol L(-1). The sensor was highly sensitive with a detection limit as low as 1.87×10(-8)molL(-1), and having a selectivity of over four thousand fold. The response time of the sensor was found to be 5 min. When stored in a desiccator at room temperature the sensor showed good stability after a 5 month period. The fluorescence sensors were successful in the determination of Pb(2+) in water samples as well as in the determination of the quantitative amount of lead and the results were satisfying. Compared with previously reported literature, the prepared new sensor is highly sensitive and selective.