In this paper, two new compounds, (1) and (2), have been synthesized by a one pot process at the reflux condition. Both compounds were characterized by infrared and UV-visible spectroscopy techniques, as well as by X-ray diffraction. The compound (1) crystallizes in the monoclinic system with the space group P21/n and the compound (2) crystallizes in the monoclinic system but with the space group P21/c. The structure consists of a non-protonated heptamolybdates polyanions, stabilized by organoammonium groups and water molecules. The cohesion of the three-dimensional structure is ensured by hydrogen bonds between the polyanions, the organoammonium groups, and the water molecules, thereby providing significant stability to the compound.

In this study, we successfully electrochemically synthesized a polypyrrole film doped with 4-methylsulfonyl-2nitrobenzoic acid (MSNBA) within an aqueous medium containing 0.01 M MSNBA, 0.003 M NaOH, and 0.01 M pyrrole. Our investigation encompassed a thorough exploration of both electrochemical and spectroscopic properties, confirming the effective incorporation of MSNBA as a dopant within the electroactive PPy chain. The morphological characterization of the film was undertaken using scanning electron microscopy (SEM). The optical properties, particularly UV-visible absorption, and fluorescence spectroscopy, were scrutinized in a dilute DMF solution. The UV-visible absorption spectra revealed a broad absorption band centered around 292 nm, attributed to the pi ->pi* 1B - 1La/1Lb transitions of the oligo-benzenes in the film. In parallel, fluorescence spectra exhibited remarkable consistency between the solid state and solution, featuring an excitation peak at 345 nm (346 nm in solution) and an emission peak around 401 nm (403 nm in solution). Exploring the impact of copper (II) ions on absorption and fluorescence spectra unveiled a notable quenching effect along two distinct linearity domains. Various mathematical treatments, including the Stern-Volmer equation (R1 = 0.98, Ksv1 = 5.104 and R2 = 0.99, Ksv2 = 1.54.106), the Perrin equation, and the polynomial equation, were applied to elucidate the nature of this fluorescence quenching. Our findings indicated that the fluorescence extinction, as a function of Cu2+ ion concentration, aligns well with the polynomial equation, signifying a combination of dynamic and static quenching (Io/I = 1.08(+/- 0.04) + 1.46(+/- 0.44)105[Q]- 1.15(+/- 0.75)1010 [Q]2). Moreover, we explored the potential application of this method for the determination of Cu2+. Calibration graphs demonstrated excellent linearity between fluorescence intensity and Cu2+ concentration in the range of 0-5.4 mu M. Notably, the detection limit of 1.2 mu M surpassed the LOD for Cu2+ (20 mu M) in drinking water set by the EPA, suggesting the viability of this approach for sensitive detection in environmental monitoring.

Glucose detection using sensing materials has lately received interest due to the increased demand for sensitive and selective glucose sensors in pharmaceutical, clinical, and industrial settings. Carbon nanotubes (CNTs) are used intensively as a specific class of effective electrode substances in electrochemical sensing due to their large surface area and interesting physical and electrochemical characteristics. Nickel is an attractive transition metal for glucose electrooxidation with high catalytic activity. In this study, CNT/MoS2/NiNPs nanocomposites with different CNT/MoS2 ratios have been prepared by a hydrothermal reaction. The CNT/MoS2 nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR), and their morphology and composition were characterized by field emission scanning electron microscopy (FESEM). Electrocatalytic activity of the as-prepared nanomaterials towards glucose oxidation was investigated by cyclic voltammetry and amperometry in alkaline media. An excellent sensitivity value of 1212 mu A center dot mM- 1 center dot cm(-2) with a wide linear range (0.05-0.65 mM), a low detection threshold of 0.197 mu M and a short response time (3 s) were achieved by the hybrid CNT/MoS2/NiNPs sensor. Its superior catalytic activity and low cost make this hybrid very promising for applications in the direct sensing of glucose.

This review focuses on the trends and challenges, over the last ten years, in the development of electrochemical sensors based on organic conducting polymers and graphene composites for the determination of trace heavy metal ions in water. Some of these materials taken alone still have significant limitations for the selective and ultrasensitive detection of target species. Hence, it has become crucial to develop new composite materials able to overcome these limitations and to improve the sensitivity to heavy metal ions. The properties resulting from the combination of these two types of materials, which increased the electrochemical performance by offering many advantages such as improvement of catalytic activity and conductivity, fast electron transfer kinetics, large surface area and high sensitivity were reviewed. This review also presents in detail various methods (chemical, electrochemical and hydrothermal) used to prepare composites and characterization methods (spectroscopic, microscopic, electrochemical, etc.). The applications of these composites in electroanalysis of heavy metal ions have been discussed and summarized. Also, electrochemical detection methods, particularly those called "Anodic Stripping Voltammetry " have been explained and their uses in the detection of heavy metal ions in natural water have been highlighted, and the results provided.

The climacteric nature of tomatoes results in the rapid deterioration of the fruit which in turn reduces the shelf-life. Herein, the role of N,N,N-trimethyl chitosan zinc oxide nanoparticles (NTMC-ZnONPs) and the additive advantage in the quality and/or shelf-life extension of post-harvested tomato fruits was investigated. NTMC-ZnONPs was synthesized through green reduction of zinc salt in the presence of clean hydrogen gas and water-soluble N,N,N-Trimethyl chitosan as a stabilizing agent. The UV-Vis spectroscopic measurement shows that NTMC-ZnONPs exhibit a strong surface plasmon resonance at 360 nm which is true for ZnONPs. The detailed characterization of NTMC-ZnONPs confirmed the formation of ZnONPs with an average particle size of 37.6 nm. Furthermore, varied concentrations of NTMC-ZnONPs were applied by dipping unblemished tomato fruit in the solution of NTMC-ZnONPs for 60 s and thereafter stored in a plastic container. Physicochemical quality parameter data of the NTMC-ZnONPs-treated tomato fruit were collected, namely: color, total suspended solids (TSS), vitamin C, lycopene, pH, beta-carotene, shelf life, and firmness. NTMC-ZnONPs were found to significantly improve the fruit firmness, color, beta-carotene content, shelf-life, and taste of tomato fruit while the TSS was found to increase as ripening progresses. Therefore, this study ascertains the applicability and/or suitability of green NTMC-ZnONPs in the enhancement of fruit quality when coated with NTMC-ZnONPs during storage.

A new hybrid decavanadate Na-3(CH3NH3)(3) [V10O28](center dot)(CH3NH2)(center dot)14H(2)O was obtained by a simple synthesis in solution and the crystal structure was determined by single-crystal X-ray diffraction. The compound consists of decavanadate anions [V10O28](6-) isolated between sodium and methylammonium cations. The UV-Visible absorption, IR spectroscopy as well as electrochemical properties were characterized. The compound crystalizes in a triclinic system (space group P-1) with the unit cell parameters: a = 10.1584(11) angstrom, b = 10.8123(5) angstrom, c = 11.1582(7) angstrom, alpha = 107.723(4)degrees, beta = 106.811(5)degrees, gamma = 94.238(7)degrees. UV-Visible absorption spectroscopy shows a strong absorption band at 300 nm. The main IR absorption bands appear at: 954 cm(-1), 800 cm(-1), 732 cm(-1) and 580 cm(-1). The electrochemical measurement of this compound shows two reversible one-electron redox process -105 mV (I-I') and 335mV(II-II'), which was attributed to two consecutive one-electron V-V -> V-IV reductions. (C) 2022 Elsevier B.V. All rights reserved.

We report here the preparation of a second generation PPI dendrimer (G2) functionalized by 4-hydroxycoumarin based on the Manich reaction and its use for chromium (VI) removal. The literature review has shown that dendrimers are types of polymer defined by regular branches of a central monomer, which give it a tree molecular structure. Their ends carry functional groups whose arrangement gives rise to cavities that are able to receive other molecules as part of host-guest chemistry. To increase the generation or modify peripheral groupings it is possible to manipulate the properties during the synthesis of the dendrimer. Coumarins are a set of molecules with multiple beneficial properties including antioxidant, anti-inflammatory, anticancer, antibacterial, antiviral properties. It has also been shown that these molecules are good metal ion chelators and are able to modulate the activity of metrix metalloproteinases (MMPs). The study of adsorption, on a PPI dendrimer functionalized with Coumarin (C2), trivalent chromium and hexavalent chromium, shows that the kinetics are carried out in two steps with a significant removal efficiency for Cr VI (38.26%) and zero for Cr III. During this study, we kept the initial chromium concentration, pH, stirring rate, contact time and temperature constant and with the same amount of adsorbent (30 mg).

The preparation of a first generation (G1) PPI dendrimer functionalized by 4-hydroxycoumarin based on the Manich reaction and its use for chromium removal. The literature review showed that dendrimers are large tree molecules constructed by iterative processes from a molecule with at least three reactive sites. These hyper-branched and multi-functional macromolecules have a perfectly defined structure whose applications in various fields such as catalysis, materials, or biology, or even medicine are constantly developing. Indeed, these dendrimers allow the development of new organic/inorganic materials with a controlled structure, but also to modify, at the nanoscale, the surface of existing materials. Coumarins form a set of molecules with multiple beneficial properties including antioxidant, anti-inflammatory, anticancer, antibacterial, antiviral properties. These molecules have also been shown to be good metal ion chelators and are able to modulate MMPs activity. The study of the adsorption of trivalent chromium and hexavalent chromium by the PPI dendrimer functionalized with Coumarin noted C3, shows that the kinetics are carried out in two stages with a high removal yield for Cr (VI) (56.15%) and very low for Cr (III) (12.98%). In this study, an amount of 30mg of adsorbent is used keeping the initial chromium concentration (30mg/L), pH (2), stirring rate, contact time and temperature constant.

A facile hydrothermal route is investigated to prepare a new sorbent based on rGO@CNT@Fe2O3. The synthesis is easy and does not involve complex chemistry. The as prepared sorbent are characterized by scanning electron microscopy (SEM), X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Chromium ions adsorption capacity of sorbent reaches 91.7 mg/g at contact time of 240 min at 298 K, and the data is fitted to Freundlich adsorption isotherm model, with second-order kinetics. Further analysis of the mechanism proved that the binding of Cr (VI) to sorbent was mainly a synergistic effect of electrostatic attraction, and ion exchange reduction. Overall, these results shed new light on the search for new composites and revealed the potential practical application of rGO@CNT@Fe2O3 in the removal of heavy metals in solution.

In this work, highly sensitive nanocomposite materials for the recognition of lead ions in aqueous medium are developed by combining reduced graphene oxide (rGO), carbon nanotubes (CNT) and iron oxide (Fe2O3) dropcasted (as a composite) on a glassy carbon electrode (GCE). This modified electrode was used as a scaffold for polypyrrole (PPy) electrosynthesis, which leaded to the design of a new advanced functional conductive polymeric material (rGO@CNT@Fe2O3/PPy). The physicochemical properties of the composite were probed by X-ray diffraction (XRD), Raman spectroscopy, Fourier-Transform Infra-Red spectroscopy (FTIR) and Scanning Electron Microscopy. The rGO@CNT@Fe2O3/PPy films generated by this strategy exhibited excellent stability and superior conductivity than bare PPy modified surface (without rGO + CNT + Fe2O3 composite). The optimized rGO@CNT@Fe2O3/PPy electrode was applied to the detection of Pb2+ (deposition potential of -1.3 V vs. Ag/ AgCl), with peak potential of -0.6 V vs. Ag/AgCl and a higher stripping current peak (1.5 mu A/cm(2)) compared to GCE, rGO@CNT/GCE and rGO@CNT@Fe2O3/GCE. The calibration curve is linear in the range from 0.02 to 0.26 mu M (R-2 = 0.992), with a sensitivity of 162.8 mu A circle mu M (1) and a detection limit (LOD) of 0.1 nM. Moreover, the modified electrode exhibited low metallic interference, high repeatability and good reproducibility towards the detection of Pb2+. Finally, the usefulness of the nanocomposite was realized by the determination of Pb2+ in tap water.

Water pollution by heavy metals and nitrite ions is a public health concern around the world because they can degrade the quality of drinking water and cause serious diseases. Lead and cadmium are probably the most dangerous heavy metals. Indeed, lead contamination can affect fertility and pregnancy, cause infantile diseases and other mutagenic and carcinogenic effects. Exposure to cadmium can cause death in mammals, and nitrite ions are also very harmful. For all these reasons, it is necessary to find effective techniques to quantify the levels of these pollutants. Recently, there is great hope in the use of organic conducting polymers in the field of heavy metals detection. In this review, we presented studies of the toxicity of several heavy metals and nitrite ions and on their impact on the environment and human health. Also, the recent developments in the use of OCPs and their application in the detection of heavy metals and nitrite ions have been examined.