Chitosan-functionalized Ag–Cu-ferrite nanocomposite as a high-performance electrochemical sensor for ascorbic acid detection: experimental and theoretical exploration

This study aims to synthesize antimicrobial agents and their molecular docking, and DFT studies of benzothiazole-imidazolone scaffolds. Benzothiazole and imidazolone analogues are of interest due to their potential activity against microbial infections. In search of suitable antimicrobial compounds, we report here the synthesis, characterization, and biological activities of benzothiazole and imidazolone analogues (4a-l). The benzothiazole clubbed imidazolone motifs were synthesized, characterized, and screened for their antimicrobial activity. Molecular docking was carried out for the development of antimicrobial agents based on the results of biological activity obtained. We have synthesized a new series of benzothiazole-clubbed imidazolone hybrids by using multi-step reactions in the search for antimicrobial agents (4a-l). The structures were determined by 1H NMR, 13C NMR, IR, and mass spectroscopy techniques. Moreover, synthesized compounds were evaluated for their antimicrobial activity by using a Serial Broth Dilution method. In addition, molecular electrostatic potential, geometric optimization, and molecular reactivity analyses (HOMO-LUMO) of 4c, which is one of the compounds with the highest antibacterial activity, were performed. The in vitro antimicrobial activity was evaluated against pathogenic strains. Among them, compounds 4c showed the most potent biological activity against Gram-negative bacteria, E. coli with MIC values of 50 μg/mL, and compound 4c active against A. clavatus with MIC values of 100 μg/mL. Active compound 4c HUMO-LUMO energies, molecular electrostatic potential analysis, and geometric optimization parameters were calculated with a 6-31G ** base set using DFT/B3LYP theory, and the results were displayed. Molecular docking studies were performed on E. coli DNA Gyrase B to understand the binding interaction of compound 4c, and it was observed that compound 4c interacted with Arg76 amino acid of the active site through hydrophobic interaction. Benzothiazole-clubbed imidazolone hybrids (4a-l) indicated promising antimicrobial activity. Among them, compounds 4b (MIC=50 μg/mL C. albicans), 4c (MIC=50 μg/mL, E. coli), 4e (MIC= 100 μg/mL, A. niger), and 4g (MIC= 50 μg/mL, S. pyogenes) with electronwithdrawing bromo, chloro, and fluoro group at the para position of the phenyl ring on benzothiazole-imidazolone hybrids indicated remarkable potency compared to the standard drug. The geometric optimization, molecular reactivity, and MESP analyses of 4c were calculated with the B3LYP/6-31G ** base set and ΔE = ELUMO-EHOMO, which was found to be - 0.12096 eV. In addition, the binding affinity scores correlated well with the in vitro antimicrobial activity (4c), while their binding modes proposed the involvement of steric, electrostatic, and hydrogen- bonding interactions with the active site.

Vibrational spectral, density functional theory and molecular docking analysis on 4-nitrobenzohydrazide

Spectroscopic characterization and structural insights of 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione using vibrational, optical, electronic spectra, reduced density gradient and quantum chemical calculations

The adsorption processes of Li+, Li, Mg2+, and Mg on twelve adsorbents (pristine and N/BN/Si-doped hexa-peri-hexabenzocoronene (HBC) molecules) were studied using density functional theory. The molecular electrostatic potential (MESP) analyses show that the replacement of C atoms of HBC by N/BN/Si units can provide a more electron-rich system than the parent HBC molecule. Li+ and Mg2+ exhibit strong adsorption on pristine and doped HBC molecules. The adsorption energy of cations on these nanoflakes (Eads-1) was in the range of -247.44 (Mg2+/m-C40H18N2 system) to -47.65 kcal mol-1 (Li+/B21H18N21 system). Importantly, our results suggest the weaker interactions of Li+ and Mg2+ with the nanoflakes as the MESP minimum values of the nanoflakes became less negative. In all studied systems, we observed electron donation from the nanoflakes to Li+ and Mg2+. For the metal/nanoflake systems, the adsorption energy of metals on the nanoflakes (Eads-2) was in the range of -33.94 (Li/C38H18B2N2 system) to -2.14 kcal mol-1 (Mg/B21H18N21 system). Among the studied anode materials for lithium-ion batteries (LIBs), the highest cell voltage (Vcell) of 1.90 V was obtained for B21H18N21. Among the studied anode materials for magnesium-ion batteries (MIBs), the highest Vcell value of 5.29 V was obtained for m-C40H18N2. Eads-2 has a significant effect on the variation of Vcell of LIBs, while Eads-1 has a significant effect on the variation of Vcell of MIBs.

The COVID-19 pandemic, caused by SARS-CoV-2, has underscored the urgent need for effective antiviral therapies, particularly against vaccine-resistant variants. This study investigates natural xanthone derivatives as potential inhibitors of the ACE2 receptor, a critical entry point for the virus. We computationally evaluated 91 xanthone compounds derived from Swertia chirayita, identifying two promising candidates: 8-O-[β-D-Xylopyranosyl-(1→6)-β-D-glucopyranosyl]-1,7-dihydroxy-3-methoxy xanthone (XAN71) and 8-O-[β-D-Xylopyranosyl-(1→6)-β-D-glucopyranosyl]-1-hydroxy-3,7-dimethoxy-xanthone (XAN72). Molecular docking and dynamics simulations (MDDS) were performed to assess their binding energy and stability within the ACE2 active site, comparing them to the reference inhibitor MLN-4067. The top six compounds were selected based on their docking performance, followed by Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) calculations to quantify binding affinities. Additionally, molecular electrostatic potential (MEP) analysis was conducted to visualize electron density regions relevant to binding interactions. Our results demonstrate that XAN71 and XAN72 exhibit superior binding affinities of -70.97 and − 69.85 kcal/mol, respectively, outperforming MLN-4067 (-61.33 kcal/mol). MD simulations revealed stable interactions with key ACE2 residues, primarily through hydrogen bonds and hydrophobic contacts. The Molecular Electrostatic Potential(MEP) analysis further elucidated critical electron density regions that enhance binding stability. This study establishes XAN71 and XAN72 as viable candidates for ACE2 inhibition, providing a structural basis for their development as natural xanthone-based therapeutics against SARS-CoV-2. These findings highlight the potential of targeting ACE2 with natural compounds to combat COVID-19, particularly in light of emerging viral variants.

Results of X-ray diffraction study and quantum-chemical calculations revealed that molecular conformation of thioindirubin molecule creates suitable conditions for formation of intramolecular C–H···O and S···O interactions. Analysis of molecular electrostatic potential (MEP) demonstrates existence of two areas of positive MEP (σ-holes) in the outermost part of the sulfur atom on the continuation of the lines of the C–S bonds. One of these σ-holes is oriented toward region of negative MEP around the oxygen atom of carbonyl group. Such situation corresponds to formation of σ-hole or chalcogen bond. Existence of both types of bonding interactions is confirmed by topological analysis of electron density distribution using “Atoms in Molecules” (AIM) theory. Energies of the C–H···O hydrogen bond and the S···O σ-hole bond derived from AIM and NBO theories are very close.

A new electrode composed of sepiolite clay (SC) carbon paste (CP) was developed and used for the adsorptive stripping differential pulse voltammetric quantification of ascorbic acid (AA). The effects of pH, the ratios of the electrode ingredients, accumulation potential, and accumulation time were investigated. The SC/CP electrode (SC/CPE) was found to have a good linear working range (1.4 × 10−8–9.0 × 10−7 mol L−1) and the detection limit of 4.2 × 10−9 mol L−1. The sensitivity is fairly good with LOQ of 0.014 μmol L−1 and LOD of 0.0042 μmol L−1. The selectivity in the presence of some common species, i.e., Na+, Cl−, Ca2+, Mg2+, NO3 − , citric acid, and glucose, at concentrations well above those encountered in body fluids was found to be satisfactory. The SC/CPE system has a lifetime not shorter than a month and proved to be practical for the analysis of not only pharmaceutical formulations but also natural products such as vitamin C-rich fruit Rosa canina and mineral waters.

Menadione sodium bisulfite as an efficient anti-corrosion additive for mild steel in acid corrosion: Electrochemical, surface morphological and theoretical studies

The theoretical investigation of tetramethylammonium (TMA)−imidazole and TMA−furan complexes has been performed to justify the preferred structure of the cation−aromatic complexes predicated by the analysis of molecular electrostatic potential (MEP) maps of isolated aromatic systems. Such maps have been shown to be helpful in predicting the cation binding sites in cation−aromatic complexes. Our computational results show that a large part of the binding energies in the systems studied are contributed by the classical cation−π interaction. However, the optimized structure obtained in the MP2 method might be different from that obtained by the DFT method due to the influence of dispersion forces. Dispersion forces have been found to be important in the systems studied, increasing the binding energies by ∼7% and 20% for the TMA−imidazole and TMA−furan systems, respectively.

Computational, theoretical and experimental studies of four amino acids as corrosion inhibitors for brass in 3% NaCl medium

In this paper, a modified glassy carbon electrode was prepared by electrochemical method in basic media (0.5 M NaOH solutions) and was used to electrochemically detect dopamine (DA), ascorbic acid (AA), uric acid (UA) and their mixture by a differential pulse voltammetry (DPV) technique. In this simultaneous detection, the electrochemical potential difference between AA and DA was measured to be 165 mV, while between DA and UA it was 135 mV, and between AA and UA 300 mV. The potential differences were large enough to determine AA, DA, and UA individually and simultaneously. The DPV oxidation peak current was linearly dependent on DA, AA, and UA concentration in the range 3–30 μM, 25–300 μM, and 5–70 μM, with correlation coefficients of 0.994, 0.998, and 0.996, respectively. The limit of detection (S/N = 3) was found to be 2.67, 23.38 and 4.70 μM for DA, AA and UA. The modified electrode was applied to the determination of DA, AA, and UA in real samples. These results and interference studies showed that the modified electrode possesses the potential for simultaneous determination of DA, AA, and UA.

Introduction: Arbutin (ABU) inhibits tyrosinase and thus prevents the formation of melanin, therefore, it used as a skin-lightening agent. Ascorbic acid (AA) used in therapeutical fields such as improving immunity, skin disorders, amelioration of injuries and burns. Hydroquinone (HQ) as one of the important skin-bleaching agents used to lighten areas of darkened skin such as freckles, melasma, age spots, and acne scars. Moreover, owing to ability of Kojic acid (KA) in preventing melanin formation, it used in whitening products because of this ability to limit melanin production. Due to the importance of quantitative determination of the four above mention drugs loading efficiency in niosomal formulations, a great attempt was made in the current work to provide a promising sensor using voltammetric techniques. Methods and Results: BMITB/NiO/NPs/MCPE was prepared by mixing 0.2 g of 1-butyl-3-methylimidazoliumtetrafluoroborate (BMITB) as a binder, 0.8 g of paraffin, 0.1 g of NiO nanoparticles and 0.9 g of graphite powder. The electro-oxidation signals of ABU, KA, AA, and HQ were increased at the surface of modified sensor compared to the bare electrode. The obtained result shows that, at pH 7.0 phosphate buffer (0.1 M), the catalytic oxidation signals exhibited a wide linear range with a satisfactory low detection limit. Conclusions: The proposed sensor revealed good electrocatalytic activity towards ABU, KA, AA, and HQ. The proposed modified carbon paste electrode (BMITB/NiO/NPs/MCPE) was applied successfully for simultaneous analysis of trace amount of four above mention drugs in niosome carrier real samples. Keywords: Drug analysis, Voltammetric sensor, NiOnanoparticle, Modified carbon paste electrode.

Synthesis, X-ray crystal structure of Cu(II) 1D coordination Polymer: In View of Hirshfeld surface, FMO, Molecular electrostatic potential (MEP) and Natural Bond orbital (NBO) analyses

Phenytoin from antiepileptic to covid-19: Synthesis, crystal structure, DFT, HSA, MEP and green biological study of phenytoin derivative as potential covid-19 drug candidates

Semi organic compounds enable several structural and bonding methods for the molecular engineering of novel materials. The optical analysis, methyl orange doped L‐lysine sulfate (MLLS) is an innovative NLO material enabling the rate of frequency up change for stronger systems with lasers in the UV range with clear absorption. With this experimental studies the theoretical studies of the L‐lysine sulfate and its molecules were studied using Gaussian09w software. X‐ray analysis, UV, FTIR, NMR, Mulliken Charges, HOMO‐LUMO, MEP and some related thermodynamic properties were studied. The chosen nucleophilic site is symbolized by the color red, the more popular electrophilic site has been highlighted during MEP mapping. Spectroscopical and thermodynamical properties related to functional behavior of molecules were also discussed with obtained results.