Electrochemiluminescent determination of peroxydisulfate with Cr(bpy)33+ in purely aqueous solution

Simultaneous determination of peroxydisulfate and bisulfite concentrations with quenching-agent-assisted iodometry

Fenton/Fenton-like reactions have gained popularity for their remarkable proficiency in decomposing organic pollutants, especially when enhanced by reductants addition for accelerating the Fe2+ regeneration. Nevertheless, these works predominantly centered on the formation and utilization of hydroxyl radicals (•OH) in the process, neglecting the evolution of oxidant and reductant due to the difficulty in the simultaneous determination of these two components. By employing the quenching-iodometric method, we could simultaneously determine the concentrations of HSO3- and peroxydisulfate (PDS). This method first employed an excess of peroxymonosulfate (PMS) to effectively quench HSO3-, and then used the iodometric spectrophotometry to simultaneously determine the concentrations of PMS and PDS in the reaction system. Finally, through precise stoichiometric relationships, we could accurately calculate the concentration of HSO3-. Based on this method, we achieved concentration measurements that, upon linear fitting, yielded a correlation coefficient (R2) surpassing 0.99, unequivocally affirming the method's accuracy and trustworthiness. In this work, an innovation approach for determining the concentrations of HSO3- (reductant) and PDS(oxidant) was explored. Additionally, the resilience of the method was verified across different pH levels and in the presence of diverse impurity ions. The results ensured precise concentration measurements in the real wastewater. This method was characterized by its simplicity, rapid analysis, and environmental friendliness, offering a new analytical strategy for the determination of PDS and HSO3- in environmental samples. The method enables more meticulous monitoring of chemical usage in water treatment, facilitating optimized dosing strategies and assessments of reductant-enhanced Fenton or Fenton-like system in water purification.

Electrochemiluminescence of a First-Row d6 Transition Metal Complex

We report the electrochemiluminescence (ECL) of a 3d6 Cr(0) complex ([Cr(LMes)3]; λem=735 nm) with comparable photophysical properties to those of ECL-active complexes of 4d6 or 5d6 precious metal ions. The electrochemical potentials of [Cr(LMes)3] are more negative than those of [Ir(ppy)3] and render the [Cr(LMes)3]* excited state inaccessible through conventional co-reactant ECL with tri-n-propylamine or oxalate. ECL can be obtained, however, through the annihilation route in which potentials sufficient to oxidise and reduce the luminophore are alternately applied. When combined with [Ir(ppy)3] (λem=520 nm), the annihilation ECL of [Cr(LMes)3] was greatly enhanced whereas that of [Ir(ppy)3] was diminished. Under appropriate conditions, the relative intensities of the two spectrally distinct emissions can be controlled through the applied potentials. From this starting point for ECL with 3d6 metal complexes, we discuss some directions for future development.

Exploiting poly(safranine) and poly(luminol) for sensing applications. A mini review

Sensor applications have captivated numerous scientists in the electroactivity field lately. Between toxic target analytes and biomolecules, many articles investigated the function of the obtained products in sensing utilization and the ability of applying the gained sensor in real sample tests. Safranine and luminol have a unique polymeric constructor combined with different nanomaterials and have been explored as sensors for different analytes through electrochemical and chemical techniques. This work presents the first review of poly(safranine) and poly(luminol) in sensor applications toward assorted analytes. An illustration for the two main types of oxidative polymerization synthetic methods for our targeted compounds has been displayed including chemical and electrochemical techniques. Furthermore, a comprehensive summary for their impressive impact as electrochemical sensors in the last few decades has been additionally introduced.

Safranine and luminol having a unique polymeric constructor combined with different nanomaterials were explored as sensors for different analytes through electrochemical and chemical techniques.

Multi-wavelength spectrophotometric measurement of persulfates using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as indicator

A spectrophotometric method using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the indicator was proposed for measuring persulfates, i.e., peroxymonosulfate (PMS) and peroxydisulfate (PDS). This method was based on the direct oxidation of the colorless ABTS by PMS/PDS to generate the green-colored ABTS⁺ at neutral pH and room temperature. The generated ABTS⁺ had four different characteristic absorption peaks at 820 nm, 732 nm, 650 nm and 415 nm. The absorption values at these wavelengths increased with the increase of PMS/PDS concentration, and there were well linear relationships (R² > 0.998) between the corresponding absorption values and the concentrations of PMS/PDS in the range of 3-500 μM. Monitoring the change of PMS/PDS concentration by the proposed ABTS method was in good agreement with that monitored by the common spectrophotometric method using potassium iodide as the indicator. The green-colored waste solutions produced after PMS/PDS analysis with the ABTS method showed no bactericidal effect towards Escherichia coli. The proposed multi-wavelength spectrophotometric method using ABTS as the indicator could be employed as a candidate method for the accurate and convenient measurement of PMS/PDS in water.

Influence of Luminol Doping of Poly(o-phenylenediamine) on the Spectral, Morphological, and Fluorescent properties: A Potential Fluorescent Marker for Early detection and Diagnosis of Leishmania donovani

There has been a steady progress in the development of doped conjugated polymers to remarkably improve their photo physical properties for their application as biomarkers. With a view to enhance the spectral, morphological, and photo physical properties of poly(o-phenylenediamine) (POPD), the present work reports the synthesis of poly(o-phenylenediamine) and doping of this polymer using luminol. The formation of luminol-doped POPD was confirmed by infrared and ultraviolet-visible spectroscopies and X-ray diffraction studies. The energy band gap values and oscillator strength of luminol in acidic, basic, and neutral media were computed by density functional theory calculations using the B3LYP/6-31G (d) basis set and were compared with experimental data. The luminol doped POPDs show significant in vitro anti-leishmanial activity. Live cell imaging also proved that these molecules bind with the organelle of Leishmania also. These luminol doped POPDs were found non-toxic at the used concentrations on THP-1 derived human macrophage cells through methyl tetrazolium (MTT) assay. The results revealed that luminol doped POPDs were potentially non-toxic to human cells though exhibited immense potential to be used as a fluorescent marker to label Leishmania donovani for diagnostic and other studies.