A series of rhodanine derivatives was synthesized in the Knoevenagel condensation of rhodanine and different aldehydes using choline chloride:urea (1:2) deep eutectic solvent. This environmentally friendly and catalyst free approach was very effective in the condensation of rhodanine with commercially available aldehydes, as well as the ones synthesized in our laboratory. All rhodanine derivatives were subjected to 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity investigation and quantitative structure-activity relationship (QSAR) studies were performed to elucidate their structure-activity relationship. The best multiple linear QSAR model demonstrate a stability in the internal validation and Y-randomization (R2 = 0.81; F = 24.225; Q2loo = 0.72; R2Yscr = 0.148). Sphericity of the molecule, ratio of symmetric atoms enhanced atomic mass along the principle axes in regard to total number of atoms in molecule, and 3D distribution of the atoms higher electronegativity (O, N, and S) in molecules are important characteristic for antioxidant ability of rhodanine derivatives. Molecular docking studies were carried out in order to explain in silico antioxidant studies, a specific protein tyrosine kinase (2HCK). The binding interactions of the most active compound have shown strong hydrogen bonding and van der Waals interactions with the target protein.

Long-life, low-cost and fast-response graphite pencil lead surfactant sensors based on MWCNTs.

The botanical origin of starch is of importance in industrial applications and food processing because it may influence the properties of the final product. Current microscopic methods are time-consuming. Starch consists of an origin-dependent amylose/amylopectin ratio. Triiodide ions bind characteristically to the amylose and amylopectin depending on the botanical origin of the starch. The absorbance of the starch-triiodide complex was measured for wheat, potato, corn, rye, barley, rice, tapioca and unknown origin starch, and within the different cultivars. Each starch sample had specific parameters: starch-triiodide complex peak wavelength maximum (λmax/nm), maximum absorbance change at λmax (ΔA) and λmax shift towards the unknown origin starch sample values. The visible absorption spectra (500-800 nm) for each starch sample were used as a unique fingerprint, and then elaborated by cluster analysis. The cluster analysis managed to distinguish data of two clusters, a cereal type cluster and a potato/tapioca/rice starch cluster. The cereal subclusters extensively distinguished wheat/barley/rye starches from corn starches. Data for cultivars were mostly in good agreement within the same subclaster. The proposed method that combines cluster analysis and visible absorbance data for starch-triiodide complex was able to distinguish starch of different botanical origins and cultivars within the same species. This method is simpler and more convenient than standard time-consuming methods.

A new solid‐state sensor for potentiometric determination of surfactants with a layer of multi‐walled carbon nanotubes was prepared. As a sensing material, 1,3‐didecyl‐2‐methylimidazolium–tetraphenylborate ion‐pair was used. The investigated sensor showed a Nernstian response for both dodecylbenzenesulphonate (DBS, 57.6 mV/decade of activity between 5 × 10−7 to 1 × 10−3 M) and sodium lauryl sulfate (LS, 58.4 mV/decade of activity between 2 × 10−7 to 2 × 10−3 M). It responded in 8–10 s for each ten‐fold concentration change in the range of 1 × 10−6 to 3 × 10−3 M. The detection limits for DS and DBS were 2 × 10−7 and 3 × 10−7 M, respectively. The sensor revealed a stable response (signal drift 2.6 mV/h) and exhibited satisfactory selectivity performances for LS over most of the anions generally used in surfactant‐based commercial detergents. The main application of this sensor was the end‐point determination in potentiometric titrations of anionic surfactants. The (diisobutyl phenoxy ethoxy ethyl)dimethyl benzyl ammonium chloride (Hyamine), cetyltrimethylammonium bromide, hexadecylpyridinium chloride monohydrate (HDPC) and 1,3‐didecyl‐2‐methylimidazolium chloride were tested as potential cationic titrants, and all exhibited analytically usable titration curves with well‐defined equivalence points. The standard solution of HDPC was used as a cationic titrant by all potentiometric titrations. The operational life‐time of the sensor described was prolonged to more than 3 months.

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