A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and ΔN values. The most efficient drugs are found with pK_a ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.

A series of novel 1-N-α-d-glucopyranosyl-1H-1,2,3-triazole xanthines was synthesized from azido sugars (glucose, galactose, and lactose) and propargyl xanthines (theophylline and theobromine) using a typical copper (I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition. The corrosion inhibition activities of these new carbohydrate-xanthine compounds were evaluated by studying the corrosion of API 5 L X70 steel in a 1 M HCl medium. The results showed that, at 10 ppm, a 90% inhibition efficiency was reached by electrochemical impedance spectroscopy. The inhibitory efficiency of these molecules is explained by means of quantum chemical calculations of the protonated species with the solvent effect, which seems to better represent the actual situation of the experimental conditions. Some quantum chemical parameters were analyzed to characterize the inhibition performance of the tested molecules.

This work presents a comparative study of five rare earth compounds—Erbium nitrate pentahydrate lll (Er), Neodymium nitrate pentahydrate (Nd), Samarium III Nitrate Hexahydrate (Sm), Yterbium III Chloride Hexahydrate (Yb) and Praseodymium nitrate hexahydrate lll (Pr)—protecting API 5L X70 steel from corrosion in saline medium that uses electrochemical impedance spectroscopy (EIS) and polarization curves (CPs) at different concentrations and in static mode. The results show that Erbium is the best corrosion inhibitor, containing 50 ppm and reaching an inhibition efficiency of about 89%, and similar result was shown by Sm with an IE~87.9%, while the other rare earths (Nd, Yb and Pr) showed a decrease in corrosion protection at the same concentration, since they were below an IE~80%. On the other hand, with the Langmuir model it was possible to describe that the adsorption process of the three rare earths follows a combined physisorption–chemisorption process to protect the metal’s surface. The observed adsorption free energy, ΔG°ads, reaches −38.7 kJ/mol for Er, −34.4 kJ/mol for Nd, and −33.6 kJ/mol for Pr; whereas Sm and Yb have adsorption free energies of −33.9 and −35.0 kJ/mol, respectively. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) further confirmed the formation of a protective film. Their characterization using density functional theory showed the transference of charge from the iron cluster towards the rare earth metal compounds. The adsorption process produced a slightly polarized region of interaction with the metal surface. Also, it was found that the adsorption of the rare earths affected the magnetic properties of the surface of the iron cluster. Quantum chemical descriptors, such as Pearson’s HSAB (Hard and Soft Acids and Bases) descriptors, were useful in predicting the behavior of the flow of electrons between the metal surface and the interacting rare earth ions.

TiO₂:Ln³⁺ (Ln³⁺: Ce³⁺, Yb³⁺ and Sm³⁺) nanoparticles were prepared by solgel method under laboratory ambient conditions by using titanium tetraisopropoxide (C₁₂H₂₈O₄Ti) as the TiO₂ source and template, and the as-synthetized samples were characterized by XRD and UV-vis DRS techniques. XRD patterns shows that the as- prepared nanomaterials exhibit tetragonal anatase-phase. The photoactivity of the synthetized catalysts was tested in the photocatalytic degradation of a Rhodamine B solution exposed to the following radiation wavelenghts (254 nm, 350 nm, 365 nm, and 385 nm). UV-vis espectroscopy analysis of the samples was used to estimate the band gap energy of the samples.

In the present research work, a study and characterization of pedernal was carried out from the little hill the la Bolita located in the Municipality of Tepalcingo, Morelos, Mexico. By last X-ray powder diffraction (XRD) the a-cuarzo mineralogical phase was determined. By Dispersive Energy Spectroscopy (EDS), The following elements were obtained, such as: Carbon, Oxygen and Silicon and the following percentages by weight 11.42, 56.59 y 31.48 respectively. The chemical compounds found were CaCO₃’ AL₂O₃ and SiO₂. The morphology of the crystals was determined by Scanning Electron Microscopy (SEM), with pseudopolygonal shape and crystallite size of 100 µm. This material was also characterized by Atomic Force Microscopy (AFM) shows the flat and three-dimensional surface shape of the rugged area in the sweep. A granular quasi-flat surface with grains was found on its surface. From these studies it was possible to characterize it as white quartz mineral α- SiO₂.

En este estudio, se elaboraron películas poliméricas de alcohol polivinílico (PVA) con complejo mononuclear de europio. Para la preparación del complejo mononuclear se empleó óxido de europio, se usaron dos rutas de síntesis preparando cloruro y nitrato de europio. Posteriormente, las disoluciones de estos precursores se combinaron con benzoato de sodio para formar los complejos. Estas rutas permitieron elucidar diferencias en la intensidad luminiscente de los polvos de compuestos mononucleares y las películas poliméricas de PVA. Mediante la espectroscopía FT-IR se identificaron los grupos funcionales y la interacción entre el ion metálico y los ligandos, confirmando la formación de complejos. Las micrografías SEM revelaron diferencias significativas en la morfología de los polvos obtenidos, siendo las partículas sintetizadas a partir del nitrato más homogéneas que las obtenidas con el cloruro. El análisis de difracción de rayos X mostró un ordenamiento estructural en los complejos, confirmando la cristalinidad. Por último, los estudios de luminiscencia revelaron una mayor intensidad luminiscente en los complejos sintetizados por la ruta del nitrato, destacando las transiciones características del ion Eu³⁺, con una mejor dispersión y emisión en los recubrimientos de PVA comparados con los polvos.