Adsorption and Inhibition Mechanisms of New Pyrazole Derivatives for Carbon Steel Corrosion in Hydrochloric Acid Solutions Based on Experimental, Computational, and Theoretical Calculations

The study aims to synthesize two green pyrazole compounds, N-((1H-pyrazol-1-yl)methyl)-4-nitroaniline (L4) and ethyl 5-methyl-1-(((4-nitrophenyl)amino)methyl)-1H-pyrazole-3-carboxylate (L6), and test their action as corrosion inhibitors for carbon steel (CS) in a 1 M HCl solution. Both chemical and electrochemical methods, namely, gravimetric measurements (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), were used to assess the efficiency of the investigated molecules. DFT calculations at B3LYP/6-31++G (d, p) and molecular dynamics simulation were used to carry out quantum chemical calculations in order to link their electronic characteristics with the findings of experiments. The organic products exhibited good anticorrosion ability, with maximum inhibition efficiencies (IE %) of 91.8 and 90.8% for 10-3 M L6 and L4, respectively. In accordance with PDP outcomes, L6 and L4 inhibitors act as mixed-type inhibitors. Assessment of the temperature influence evinces that both L4 and L6 are chemisorbed on CS. The adsorption of L4 and L6 on CS appears to follow the Langmuir isotherm. Scanning electron microscopy and UV-visible disclose the constitution of a barrier layer, limiting the accessibility of corrosive species to the CS surface. Theoretical studies were performed to support the results derived from experimental techniques (WL, PDP, and EIS).

Synthesis of novel pyrazolone candidates with studying some biological activities and in-silico studies

Pyranopyrazole derivatives have a vital role in the class of organic compounds because of their broad spectrum of biological and pharmacological importance. Our current goal is the [3 + 3] cycloaddition of benzoyl isothiocyanate and pyrazolone 1 to undergo oxidation cyclization, producing pyrazoloxadiazine 3. The diol 5 was obtained as a condensation of two equivalents of 1 with thiophene-2-carboxaldehyde in acetic acid above the sodium acetate mixture. When the condensation was carried out in piperidine under fusion, unsaturated ketone 4 was obtained. The pyrazolo pyran derivative 11 resulted from the [3 + 3] cycloaddition of 1 and cinnamic acid, while the Pyrone derivative was prepared by acylation of 12 with two equivalents of acetic anhydride. Phthalic anhydride undergoes arylation using zinc chloride as a catalyst. The cyclic keto acid 23 was synthesized by the action of succinic anhydride on 12 in the acetic medium, while the latter reacted with cinnamic acid, leading to pyrazole derivative 24. All of these reactions were through the Michael reaction mechanism. All the tested compounds showed good antimicrobial activity against pathogenic microorganisms; newly synthesized compounds were also screened for their antioxidant activity. Rational studies were carried out by the ABTs method to allow a broader choice of activities. In addition, similar off-compounds were conducted. Molecular docking studies with the CB-Dock server and MD simulations were created with the default settings of the Solution Builder on the CHARMM-GUI server at 150 nm. A good correlation was obtained between the experimental results and the theoretical bioavailability predictions using POM theory.

Ultrasonic Clusterization Process to Prepare [(NNCO)6Co4Cl2] as a Novel Double-Open-Co4O6 Cubane Cluster: SXRD Interactions, DFT, Physicochemical, Thermal Behaviors, and Biomimicking of Catecholase Activity

A novel double-open-cubane (NNCO)₆Co₄Cl₂ cluster with a Co₄O₆ core was made available under aqua-ultrasonic open atmosphere conditions for the first time. The ultrasonic clusterization of the (3,5-dimethyl-1H-pyrazol-1-yl)methanol (NNCOH) ligand with CoCl₂·6H₂O salts in ethanol yielded a high-purity and high-yield cluster product. Energy-dispersive X-ray (EDX), Fourier transform infrared (FT-IR), and ultraviolet (UV)-visible techniques were used to elucidate the clusterization process. The double-open-Co₄O₆ cubane structure of the (NNCO)₆Co₄Cl₂ cluster was solved by synchrotron single-crystal X-ray diffraction (SXRD) and supported by density functional theory (DFT) optimization and thermogravimetric/differential TG (TG/DTG) measurements; moreover, the DFT structural parameters correlated with the ones determined by SXRD. Molecular electrostatic potential (MEP), Mulliken atomic charge/natural population analysis (MAC/NPA), highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO), density of states (DOS), and GRD quantum analyses were computed at the DFT/B3LYP/6-311G(d,p) theory level. The thermal behavior of the cluster was characterized to support the formation of the Co₄O₆ core as a stable final product. The catalytic property of the (NNCO)₆Co₄Cl₂ cluster was predestined for the oxidation process of 3,5-DTBC diol (3,5-di-tert-butylbenzene-1,2-diol) to 3,5-DTBQ dione (3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione).

Petra/Osiris/Molinspiration and Molecular Docking Analyses of 3-Hydroxy-Indolin-2-one Derivatives as Potential Antiviral Agents

BACKGROUND

Studies on the interaction between bioactive molecules and HIV-1 virus have been the focus of recent research in the scope of medicinal chemistry and pharmacology.

OBJECTIVE

Investigating the structural parameters and physico-chemical properties of elucidating and identifying the antiviral pharmacophore sites.

METHODS

A mixed computational Petra/Osiris/Molinspiration/DFT (POM/DFT) based model has been developed for the identification of physico-chemical parameters governing the bioactivity of 22 3-hydroxy-indolin-2-one derivatives of diacetyl-L-tartaric acid and aromatic amines containing combined antiviral/antitumor/antibacterial pharmacophore sites. Molecular docking study was carried out with HIV-1 integrase (pdb ID: 5KGX) in order to provide information about interactions in the binding site of the enzyme.

RESULTS

The POM analyses of physico-chemical properties and geometrical parameters of compounds 3a-5j, show that they are bearing a two combined (O,O)-pockets leading to a special platform which is able to coordinate two transition metals. The increased activity of series 3a-5j, as compared to standard drugs, contains (Osp²,O sp³,O sp²)-pharmacophore site. The increase in bioactivity from 4b (R¹, R² = H, H) to 3d (R¹, R² = 4-Br, 2-OCH₃) could be attributed to the existence of π-charge transfer from para-bromo-phenyl to its amid group (CO^δ---NH^δ+). Similar to the indole-based reference ligand (pdb: 7SK), compound 3d forms hydrogen bonding interactions between the residues Glu170, Thr174 and His171 of HIV-1 integrase in the catalytic core domain of the enzyme.

CONCLUSION

Study confirmed the importance of oxygen atoms, especially from the methoxy group of the phenyl ring, and electrophilic amide nitrogen atom for the formation of interactions.

Synthesis of Novel Tetra(µ3-Methoxo) Bridged with [Cu(II)-O-Cd(II)] Double-Open-Cubane Cluster: XRD/HSA-Interactions, Spectral and Oxidizing Properties

A new double-open-cubane core Cd(II)-O-Cu(II) bimetallic ligand mixed cluster of type [Cl2Cu4Cd2(NNO)6(NN)2(NO3)2].CH3CN was made available in EtOH/CH3CN solution. The 1-hydroxymethyl-3,5-dimethylpyrazole (NNOH) and 3,5-dimethylpyrazole (NNH) act as N,O-polydentate anion ligands in coordinating the Cu(II) and Cd(II) centers. The structure of the cluster in the solid state was proved by XRD study and confirmed in the liquid state by UV-vis analysis. The XRD result supported the construction of two octahedral and one square pyramid geometries types around the four Cu(II) centers and only octahedral geometry around Cd(II) two centers. Interestingly, NNOH ligand acts as a tetra-µ3-oxo and tri-µ2-oxo ligand; meanwhile, the N-N in NNH acts as classical bidentate anion/neutral ligands. The interactions in the lattice were detected experimentally by the XRD-packing result and computed via Hirschfeld surface analysis (HSA). The UV-vis., FT-IR and Energy Dispersive X-ray (EDX), supported the desired double-open cubane cluster composition. The oxidation potential of the desired cluster was evaluated using a 3,5-DTB-catechol 3,5-DTB-quinone as a catecholase model reaction.

Crystal structure of tris-(2,2'-bi-pyridine)-cobalt(II) bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide)

In the title compound, [Co(C10H8N2)3](C9H5N4O)2, the tris-(2,2'-bi-pyridine)-cobalt(II) dication lies across a twofold rotation axes in the space group C2/c. The N atoms of the three bi-pyridine ligands form a distorted octa-hedron around the cobalt ion. All the N atoms of the polynitrile 1,1,3,3-tetra-cyano-2-eth-oxy-propenide anions participate in C-H⋯N hydrogen bonds ensuring crystal cohesion and forming a three-dimensional structure. The structure is further stabilized by C-H⋯π(cation) and anion⋯π(cation) inter-actions.

Paramphistomum daubneyi: characteristics of infection in three lymnaeid species

Experimental infections of two South American lymnaeids (Lymnaea neotropica and L. viatrix var. ventricosa) with Paramphistomum daubneyi were carried out to determine if these snail species could sustain larval development of this digenean and, if so, to specify their potential for cercarial production. A French population of Galba truncatula infected and raised according to the same protocol served as controls. In both experiments, prevalence of P. daubneyi infections in snails did not significantly differ from each other. In snail groups evaluated for cercarial shedding (first experiment), a significantly lower number of shed cercariae was noted for L. neotropica, while those from G. truncatula and L. v. ventricosa did not differ significantly from each other. Dissection of infected snails at day 65 post-exposure at 20 °C (second experiment) found significantly lower burdens of P. daubneyi rediae and cercariae in the bodies of L. neotropica than in those of G. truncatula and L. v. ventricosa. Compared to total cercarial production observed in dissected snails, the percentage of cercariae which exited from snails was 75.6% for G. truncatula, 21.6% for L. neotropica, and 91.4% for L. v. ventricosa. This last species seems to be a good candidate for metacercarial production of P. daubneyi.

The proportion of liver excised in Algerian abattoirs is not a good indicator of Fasciola hepatica infections in local cattle breeds

Clinical and serological investigations on 175 cattle were carried out in 1999 at the slaughterhouse of Jijel, northeastern Algeria, to verify if partial ablation of a liver infected with Fasciola hepatica represents a good epidemiological indicator in the case of fasciolosis, as partial excision of the liver is widespread throughout North African countries. This study was also performed to determine if there is a direct relationship between the quantity of liver confiscated for fasciolosis and the serological response of slaughtered animals. A significant relationship between highly infected livers and positive serological titres was noted. However, two groups of results were conflicting: the presence of macroscopically healthy, undamaged livers with a positive serology (8.3% of 120 cattle), or the existence of highly damaged livers with a negative serology (13.0% of 31 cattle). These results indicate that partial removal of the liver in the case of fasciolosis is unreliable, so this method does not represent a good tool to establish epidemiological data on this disease.