IN SILICO MODEL QSPR FOR PREDICTION OF STABILITY CONSTANTS OF METAL-THIOSEMICARBAZONE COMPLEXES

In the present work, the stability constants logb11 and the concentration of metal ion and thiosemicarbazone in complex solutions were determined by using in silico models. The 2D, 3D, physicochemical and quantum descriptors of complexes were generated from the molecular geometric structure and semi-empirical quantum calculation PM7 and PM7/sparkle. The quantitative structure and property relationships (QSPRs) were constructed by using the ordinary linear regression (OLR) and artificial neural network (ANN). The best linear model QSPROLR (with k of 6) involved descriptors k0, core-core repulsion, xp5, xch5, valence, and SHHBd. The quality of model QSPROLR had the statistical values: R2train = 0.898, R2adj = 0.889, Q2LOO = 0.846, MSE = 1.136, and Fstat = 91.348. The neural network model QSPRANN with architecture I(6)-HL(6)-O(1) had the statistical values: R2train = 0.9768, and Q2LOO = 0.8687. The predictability of QSPR models for complexes of the test group turned out to be in good agreement with those from the experimental data in the literature

Facile synthesis of high porous NiO nanostructures by hydrothermal method

In this report, the simple hydrothermal approaches to the fabrication of porous NiO nanostructures including nanospheres and nanotoroids were described.  Morphologies and crystal structure of the as-fabricated nanomaterials were characterized by various techniques such as SEM, TEM, XRD, EDS, and N2 adsorption/desorption isotherm. The results showed that the porous NiO nanospheres have the diameter ranging from 2 to 10 µm, which are self-assembled nanoparticles (NPs). The nanotoroids have an average outer particle diameter and iner diameter are of ~300 nm and ~60 nm, respectively. This simple and mild approach to fabricate highly porous NiO nanostructures could be easily scaled up and potentially extended to the synthesis of other porous nanostructured metal oxides

Search for conformation of thiosemicarbazone reagents and their complexes with metals by using Monte Carlo and docking simulation

In this study, the conformation of ML2 complexes of new thiosemicarbazone reagents with metal cations Cd2+, Ni2+, Cu2+, Hg2+, Pb2+, Mn2+, and Zn2+ is investigated. The methods include MM+ and PM3 calculations with the Monte Carlo techniques using the Metropolis algorithm in the temperature range of 298–473 K. The initial selection conformation was carried out randomly after 15 repeated conformations, and 30 conformations were rejected. The conformations were chosen to change by changing the torsional-dihedral angles at the position of the metal cation associated with the donor atoms N and S of the thiosemicarbazone reagents. This was performed by randomly changing the dihedral angles to create new structures, and then the energy values of these angles were minimized with the PM3 and MM+ calculation. The lowest suitable energies were accumulated, while high- or duplicate-energy structures were discarded. The docking method was also employed to screen the most suitable metal-thiosemicarbazone complexes that bind to the active site on the SARS-CoV-2 protein. The docking method enabled us to choose the molecular conformation of the most significant Cd2+-thiosemicarbazone complex

Simultaneous Voltammetric Determination of Ascorbic Acid, Paracetamol, and Caffeine Using Electrochemically Reduced Graphene-Oxide-Modified Electrode

In the present paper, graphene oxide was directly electrodeposited by means of cyclic voltammetric techniques on the glassy-carbon electrode (GCE) to obtain a reduced graphene-oxide-modified electrode (ErGO/GCE). Cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DP-ASV) had been utilized to study the electrochemical behavior of ErGO/GCE toward ascorbic acid (AA), paracetamol (PA), and caffeine (CA). Differential pulse voltammetry results show that AA, PA, and CA could be detected selectively and sensitively on ErGO/GCE with peak-to-peak separation of 312 mV and 756 mV for AA–PA and PA–CA, respectively. The factors affecting the voltammetric signals such as pH, scan rate, and interferents were addressed. The results reveal that the ErGO/GCE-modified electrode exhibits excellent electrochemical activity in the oxidation of PA, CA, and AA. The detection limits are 0.36 μM, 0.25 μM, and 0.23 μM for AA, PA and CA, respectively, suggesting that the ErGO/GCE can be utilized with high sensitivity and selectivity for the simultaneous determination of these compounds. Finally, the proposed method was successfully used to determine AA, PA, and CA in pharmaceutical preparations

Aminopropyl Functionalised MCM-41: Synthesis and Application for Adsorption of Pb(II) and Cd(II)

This paper shows a comparison of porous properties of aminopropyl-MCM-41 materials functionalised via the direct and indirect methods. The obtained materials were characterised using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis-differential scanning calorimeter (TGA-DSC), adsorption/desorption isotherms of nitrogen, and Fourier-transfer infrared (FT-IR) spectroscopy. The results showed that the direct method provided the aminopropyl-MCM-41 material with well-ordered pores and high surface areas but with a lower quantity of grafted 3-aminopropyltriethoxysilane than the indirect method. To remove the organic template in the indirect method, solvent extraction with HCl/C2H5OH and calcination at 500°C were used, and the former gave a higher quantity of grafted 3-aminopropyltriethoxysilane in the resulting aminopropyl-MCM-41 materials. The experimental data were applied to the isotherm models of adsorption including Langmuir, Freundlich, Redlich–Peterson, and Sips either in the linear or nonlinear form. In order to avoid the bias of the determination coefficient and the error function method, the paired-samples t-test as an alternative method was first proposed to look for the most appropriate adsorption isotherms. The maximum adsorption capacity of Cd(II) and Pb(II) was 14.08 mg·g−1 and 64.21 mg·g−1, respectively. The mechanism of complexation and isoelectric interaction was suggested to explain the adsorption of Pb(II) and Cd(II) from aqueous solutions on aminopropyl functionalised MCM-41 in the range of pH from 2 to 9

ZIF-67/g-C3N4-Modified Electrode for Simultaneous Voltammetric Determination of Uric Acid and Acetaminophen with Cetyltrimethylammonium Bromide as Discriminating Agent

In the present paper, the ZIF-67/g-C3N4 composite was synthesized and utilized as a modifier for a glassy carbon electrode for the simultaneous voltammetric determination of uric acid (URA) and acetaminophen (ACE) with cetyltrimethylammonium bromide (CTAB) as a discriminating agent. The composite was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The obtained ZIF-67/g-C3N4 composite exhibits good textural properties (specific surface area: 75 m2·g−1) and is stable in water with a pH range of 3 to 10. The ZIF-67/g-C3N4-modified electrode combined with CTAB as a discriminating agent possesses excellent catalytic electrochemistry towards URA and ACE with well-defined electrochemical responses. The electrochemical kinetics study is also addressed. The linear relation of the oxidation peak current of URA and ACE and the concentration ranging from 0.2 μM to 6.5 μM provide a detection limit of 0.052 μM for URA and 0.053 μM for ACE. The proposed method is well-suited to simultaneously analyze URA and ACE in human urine with comparable results with HPLC