Surface Complexation Modeling: II. Strategy for Modeling Polymer and Precipitation Reactions at High Surface Coverage

Three triple-layer model (TLM) surface complexation models that allow for the formation of multinuclear surface complexes or precipitates are compared, based on their ability to simulate cobalt sorption on α-Al₂O₃. These models include: (1) a surface solid solution model, (2) a surface polymer model, and (3) a surface continuum model. The solid solution model accounts for high coverage data by invoking a coprecipitation surface reaction, while the polymer model accomplishes the same task with multinuclear surface complexation reactions. In the continuum model, two polymer reactions and one precipitation reaction are proposed. Modeling results indicate that all of the models work reasonably well at predicting sorption data from moderate to high surface coverage (0.1 to 100%). Because the continuum model is the only one presented which is consistent with spectroscopic data throughout the range of surface coverages examined, this model is suggested as the preferred one for modeling metal ion sorption data. Model predictions of pH-edge and isotherm data are discussed and used in the assessment of the merits of the three TLM models.     

SAMPL4 & DOCK3.7: lessons for automated docking procedures

The SAMPL4 challenges were used to test current automated methods for solvation energy, virtual screening, pose and affinity prediction of the molecular docking pipeline DOCK 3.7. Additionally, first-order models of binding affinity were proposed as milestones for any method predicting binding affinity. Several important discoveries about the molecular docking software were made during the challenge: (1) Solvation energies of ligands were five-fold worse than any other method used in SAMPL4, including methods that were similarly fast, (2) HIV Integrase is a challenging target, but automated docking on the correct allosteric site performed well in terms of virtual screening and pose prediction (compared to other methods) but affinity prediction, as expected, was very poor, (3) Molecular docking grid sizes can be very important, serious errors were discovered with default settings that have been adjusted for all future work. Overall, lessons from SAMPL4 suggest many changes to molecular docking tools, not just DOCK 3.7, that could improve the state of the art. Future difficulties and projects will be discussed.     

Spirocyclic azetidines for drug discovery: Novel Boc-protected 7'H-spiro[azetidine-3,5'-furo[3,4-d ]pyrimidines]

A novel spirocyclic scaffold of 7'H-spiro[azetidine-3,5'-furo[3,4-d]pyrimidine] chemotype was synthesized in N-Boc-protected form. However, the scaffold was revealed to be unstable to storage when deprotected. The solution was found in the brief removal of the Boc protecting group and rapid acylation of the liberated NH-azetidine with a carboxylic acid imidazolide.     

Modeling high-pressure densities at wide temperature range with volume scaling: Cyclohexane + n-hexadecane mixtures

High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range was modeled with several classical equations of state (EOS) and correlative models. A modification for softening the co-volume and another for a volume scaling of the Peng–Robinson EOS (VS-PR) were proposed. The VS-PR model is able to correlate the pure component experimental data employing only five adjustable parameters, with root-mean-square deviation (RMSD) between calculated and experimental densities essentially within the experimental error. This result is superior to widely used approaches, i.e., a six parameter Tait model and six parameter volume translations (temperature and pressure dependent) for Peng–Robinson and Patel–Teja EOS. The VS-PR model also represents well the isobaric thermal expansion and the isothermal compressibility coefficients of the pure cyclohexane, a small naphthenic substance as well as a long chain n-alkane hydrocarbon, n-hexadecane. When modeling the mixture data, the use of VS-PR model of pure components along with the Redlich–Kister expansion, truncated at the first term, the density was correlated within a RMSD only 60% greater than the experimental error. The proposed model is able to accurately represent all the tested mixture data with a relatively small number of parameters.     

Synthesis, sustained release properties of magnetically functionalized organic–inorganic materials: Amoxicillin anions intercalated magnetic layered double hydroxides via calcined precursors at room temperature

Zinc–aluminum–carbonate–layered double hydroxides (ZnAl–CO₃–LDHs), loaded with magnetic substrates (Fe₃O₄), were prepared for sustained drug-targeting delivery. From the X-ray diffraction results, it was found that the magnetic substrates were successfully incorporated with LDHs and highly dispersed in the hydrotalcite structure. After intercalation with an antibiotic drug (amoxicillin) by using a calcinations–reconstruction method, the basal spacing of layered double hydroxides increased from 7.51 Å to 12.35 Å, indicating that amoxicillin was successfully intercalated into the interlay space of LDHs as a monolayer. Furthermore, in vitro drug release experiments in pH 7.4 phosphate buffer solution (PBS) showed sustained release profiles with amoxicillin as a model drug. Magnetic measurements revealed that the composite possessed paramagnetic properties at room temperature.     

CO_2 selective hydrogenation to synthetic natural gas(SNG) over four nano-sized Ni/ZrO_2 samples:ZrO_2 crystalline phase & treatment impact

Two type zirconia(monoclinic and tetragonal phase ZrO_2) carriers were synthesized via hydrothermal route,and nano-sized zirconia supported nickel catalysts were prepared by incipient impregnation then followed thermal treatment at 300℃ to 500℃,for the CO_2 selective hydrogenation to synthetic natural gas(SNG).The catalysts were characterized by XRD,CO_2-TPD-MS,XPS,TPSR(CH_4,CO_2) techniques.For comparison,the catalyst NZ-W-400(monoclinic) synthesized in water solvent exhibited a better catalytic activity than the catalyst NZ-M-400(tetragonal) prepared in methanol solvent.The catalyst NZ-W-400 displayed more H_2 absorbed sites,more basic sites and a lower temperature of initial CO_2 activation.Then,the thermal treatment of monoclinic ZrO_2 supported nickel precursor was manufactured at three temperature of 350,400,500℃.The TPSR experiments displayed that there were the lower temperature for CO_2 activation and initial conversion(185℃) as well as the lower peak temperature of CH_4 generation(318℃),for the catalyst calcined at 500℃.This sample contained the more basic sites and the higher catalytic activity,evidenced byCO_2-TPD-MS and performance measurement.As for the NZ-W-350 sample,which exhibited the less basic sites and the lower catalytic activity,its initial temperature for CO_2 activation and conversion was higher(214℃) as well as the higher peak temperature of CH_4 formation(382℃).     

Reaction ClO + ClO → products: Modeling and parameterization for use in atmospheric models

The interaction of two ClO radicals is important in the Antarctic stratosphere. Current models assume a single ClOOCl product and use the parameters suggested in the NASA/JPL or IUPAC compilations to describe the rate constant as a function of temperature and pressure (in air). It has been noted that these parameters suggest an inordinately high energy transfer efficiency and perhaps a somewhat high negative temperature dependence at the high pressure limit. Recent potential energy surface calculations reveal the possibility of the formation of ClOClO. In this study RRKM/master equation modeling of this surface was performed. Rational input parameters confirm that the formation of ClOClO in 10–15% yields may be important, but they do not conform with the shape and temperature dependence of the data. The simplest best representation of the extant data remains the single channel NASA/JPL format with parameters k₀ (cm⁶ molecules^?2 s^?1) = 1.6 × 10^?32 (T/300)^?4.5 and k (cm³ molecules^?1 s^?1) = 2.0 × 10^?12 (T/300)^?2.4. However, the data can be represented as the sum of the two pathways as well. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 206–211, 2003     

An overview of deep eutectic solvents: Alternative for organic electrolytes,aqueous systems & ionic liquids for electrochemical energy storage

As the demand for sustainable energy sources continues to rise, the need for efficient and reliable energy storage systems becomes crucial. In order to effectively store and distribute renewable energy, new and innovative solutions must be explored. This review examines the deep eutectic solvents(DESs) as a green,safe, and affordable solution for the electrochemical energy storage and conversion field, offering tremendous opportunities and a promising future. DESs are a class of environment-frie...     

Novel Cr (III), Fe (III) and Ru (III) Vanillin Based Metallo‐Pharmaceuticals for Cancer and Inflammation Treatment: Experimental and Theoretical Studies

In this study, three novel complexes comprising trivalent Cr (III), Fe (III) and Ru (III) with imine ligand derived from 2‐amino‐3‐hydroxypyridine and o‐vanillin (H₂L) have been synthesized and characterized via wide range of spectroscopic and analytical tools such as ¹H NMR and ¹³C NMR, infrared (IR) and UV–Vis spectrophotometry, conductivity and magnetic measurements. The obtained results along with DFT data confirmed a 1:1 (metal: ligand) stoichiometry with non‐planner geometries for the three complexes. The binding action and the docking study of the prepared metal‐complexes to calf thymus DNA was also studied by absorption spectra and viscosity technique, which revealed that the three complexes interact strongly with DNA through intercalative binding mode. Significantly, these metal‐imine complexes showed strong and efficient anti‐inflammatory and antimicrobial activities against various gram‐positive (Microccus luteus), gram‐negative (Escherichia coli and Serratia marcescence) bacteria, and three strains of fungus. Moreover, all complexes exhibited more potent cytotoxicity effect on the outgrowth of different types of carcinoma cells, including human colon (HCT‐116 cell line), breast (MCF‐7 cell line), and hepatic cellular (HepG‐2), than the clinically‐proven Vinblastine standard.     

Nanoplasmonic Photoluminescence Spectroscopy at Single‐Particle Level: Sensing for Ethanol Oxidation

Surface plasmon resonances of metal nanoparticles have shown significant promise for the use of solar energy to drive catalytic chemical reactions. More importantly, understanding and monitoring such catalytic reactions at single‐nanoparticle level is crucial for the study of local reaction processes. Herein, using plasmonic photoluminescence (PL) spectroscopy, we describe a novel sensing method for catalytic ethanol oxidation reactions at the single‐nanoparticle level. The Au nanorod monitors the interfacial interaction with ethanol during the catalytic reaction through the PL intensity changes in the single‐particle PL spectra. The analysis of energy relaxation of excited electron–hole pairs indicates the relationship between the PL quenching and ethanol oxidation reaction on the single Au nanorod.     

Front Cover: Investigation of the Second Harmonic Generation at the Water–Vacuum Interface by Using Multi‐Scale Modeling Methods (ChemistryOpen 1/2023)

The Front Cover shows the interfacial selectivity of second harmonic generation at the water‐vacuum interface, which is targeted in this work. In more details, the molecular first hyperpolarizability responses have been calculated by combining classical molecular dynamics and quantum chemistry simulations, and our model was able to distinguish between the bulk and the interfacial contributions. More information can be found in the Research Article by Tárcius N. Ramos et al.     

Continuous Bulk Process for the Production of High‐Impact Polystyrene: Recent Developments in Modeling and Control

This work presents (in a wider perspective), some of our recent developments in the mathematical modeling and control of bulk polymerization for the production of HIPS. The recent model by Casís assumes the polymerization to be heterogeneous, and it calculates (in two phases) the global molecular structure of the three polymeric components of HIPS (free polystyrene, unreacted polybutadiene, and graft copolymer). At present, a model is being developed capable of estimating the average particle morphology (salami or core‐shell). Assuming a continuous bulk HIPS process as homogeneous, Luciani estimated the evolution of the MFI of the final product during changes of grade, with the aim of minimizing the intermediate off‐spec product. Finally, an unpublished simulation is presented that describes the transitions between the steady state of a HIPS‐grade and that of a general‐purpose polystyrene.