Electronic origins of the stereochemistry in β-lactam formed through the Staudinger reaction catalyzed by a nucleophile.

This paper evaluates the electronic effects of molecular substituents on the stereoselectivity of the umpolung Staudinger catalytic reaction. This is especially important because experimental studies on constructing the β-lactam ring, a core structure of most antibiotics, through catalyzed Staudinger reactions have been massively progressing over the last century. Yet, there is a necessity for an in-depth understanding of the reaction mechanisms to help chemists, working on the well-established discoveries, improve these to optimize the stereoselectivity and yield of synthetic methods.

Effect of quaternary ammonium surfactants on biomembranes using molecular dynamics simulation.

Research conducted both prior to and after the emergence of the COVID-19 pandemic reveals a notable rise in human exposure to cleaning products, hand sanitizers, and personal care items. Moreover, there has been a corresponding increase in the environmental release of these chemicals. Cleaning and disinfecting products often contain quaternary ammonium compounds (QACs) with alkyl chains as long as 8-12 carbon atoms.

The effect of various partial atomic charges on the bulk and liquid/vacuum interface properties of iodobenzene derivatives at their melting points.

In this work, various atomic charge schemes including natural bond orbital (NBO), electrostatic potential based (CHELPG), and σ-hole model charges were applied in the OPLS-AA force field to investigate their effects on the thermophysical and structural properties of iodobenzene and its derivatives. Molecular dynamics simulations presented in this work show that the studied structural and thermophysical properties are in good agreement with experiments when the CHELPG charge was coupled with the OPLS-AA force field. Also, the arrangement of iodobenzene derivatives in the liquid phase was investigated via combined radial/angular distribution functions (CDFs) analyses and halogen-bonding theory.

The interactions of folate with the enzyme furin: a computational study.

Entrance of coronavirus into cells happens through the spike proteins on the virus surface, for which the spike protein should be cleaved into S1 and S2 domains. This cleavage is mediated by furin, a member of the proprotein convertases family, which can specifically cleave Arg-X-X-Arg↓ sites of the substrates. Here, folate (folic acid), a water-soluble B vitamin, is introduced for the inhibition of furin activity.

Synthesis of some new distyrylbenzene derivatives using immobilized Pd on an NHC-functionalized MIL-101(Cr) catalyst: photophysical property evaluation, DFT and TD-DFT calculations.

In this study the catalytic application of a heterogeneous Pd-catalyst system based on metal organic framework [Pd-NHC-MIL-101(Cr)] was investigated in the synthesis of distyrylbenzene derivatives using the Heck reaction. The Pd-NHC-MIL-101(Cr) catalyst showed high efficiency in the synthesis of these π-conjugated materials and products were obtained in high yields with low Pd-contamination based on ICP analysis. The photophysical behaviors for some of the synthesized distyrylbenzene derivatives were evaluated.

Significant Improvement in CO Absorption by Deep Eutectic Solvents as Immobilized Sorbents: Computational Analysis.

To find an alternative way for improving the efficacy of deep eutectic solvents (DESs) to dissolve carbon dioxide, a computational study of DES systems comprising choline chloride and different hydrogen-bond donors (ethylene glycol and glycerol) immobilized on hydrophobic (graphite) and hydrophilic (titanium dioxide) solid surfaces was performed. This research provides quantitative molecular understanding of the role of the DES thickness and also the type of solid support in CO sorption and diffusion using molecular dynamics simulations. In general, the proposed model based on supported DESs immobilized on different supports was developed to correlate the solubility of CO in DESs based on choline chloride.

Encapsulation and Release of Doxorubicin from TiO Nanotubes: Experiment, Density Functional Theory Calculations, and Molecular Dynamics Simulation.

Titanium dioxide (TiO) nanotubes are attractive materials for drug-delivery systems because of their biocompatibility, chemical stability, and simple preparation. In this study, we loaded TiO nanotubes with anticancer drug doxorubicin (DOX) experimentally and in all-atom molecular dynamics (MD) simulations. The release of doxorubicin from the nanotubes was studied by high-performance liquid chromatography (HPLC) and confocal Raman spectroscopy, and drug-release profiles were evaluated under various conditions.

Aqueous solutions of binary ionic liquids: insight into structure, dynamics, and interface properties by molecular dynamics simulations and DFT methods.

The behavior of aqueous solutions of mixtures of ionic liquids (ILs) is of special interest because of their amphiphilic character, from both a fundamental and application viewpoint. In this work, we conducted molecular dynamics (MD) simulations and density functional theory (DFT) calculations to understand the effect of water on the intermolecular interactions in three IL binary mixtures [C4mim]/[Cl]/[BF4], [C4mim]/[Cl]/[PF6] and [C4mim]/[BF4]/[PF6] containing the well-characterized cation, 1-n-butyl-3-methylimidazolium [C4mim]+ and the anions chloride [Cl]-, tetrafluoroborate [BF4]-, and hexafluorophosphate [PF6]-. The perturbation of the structures in the binary IL mixture by water molecules was analyzed in the bulk and at the liquid/vacuum interface using distribution functions, hydrogen-bond statistics, and density profiles.

New insight into electrosynthesis of ordered TiO nanotubes in EG-based electrolyte solutions: combined experimental and computational assessment.

To obtain a better understanding of TiO2 nanotube (TiO2-NT) synthesis in different ethylene glycol (EG)-based electrolyte solutions by electrochemical anodization, the primary steps of TiO2-NT formation were studied by experimental techniques. In this regard, three different EG-based electrolyte solutions were used for anodic oxidation of titanium foil. The first electrolyte solution contains conventional ammonium fluoride (NH4F) dissolved in EG/water (98 : 2 v/v).

The interactions of an Aβ protofibril with a cholesterol-enriched membrane and involvement of neuroprotective carbazolium-based substances.

Recent studies have shown that the aggregation of the amyloid-beta peptide (Aβ) in the brain cell membrane is responsible for the emergence of Alzheimer's disease (AD); the exploration of effective factors involved in the extension of the aggregation process and alternatively the examination of an effective inhibitor via theoretical and experimental tools are among the main research topics in the field of AD treatment. Therefore, in this study, we used all-atom molecular dynamics (MD) simulations to clarify the impact of cell membrane cholesterol on the interaction of Aβ with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as a membrane model. Moreover, the effect of the P7C3-S243 molecule on the abovementioned process was investigated.

Interactions of neutral gold nanoparticles with DPPC and POPC lipid bilayers: simulation and experiment.

Molecular dynamics simulations of neutral gold nanoparticles (AuNPs) interacting with dipalmitoylphosphatidylcholine (DPPC) and 1-palmitoyl-2-oleoyl--3-phosphocholine (POPC) membranes were studied using a model system. Spontaneous membrane insertion of AuNPs did not occur on the time scale of atomistic simulations. To overcome the limitations of time scale, we used a harmonic restraining potential to force the AuNPs into the membranes.

Confinement of aqueous mixtures of ionic liquids between amorphous TiO slit nanopores: electrostatic field induction.

Electrostatic potential in the vicinity of the surface is induced when aqueous mixtures of hydrophobic and hydrophilic ionic liquids (ILs) are confined between a slit nanopore of amorphous but not crystalline TiO2 semiconductors. According to our molecular dynamics (MD) simulations, the extent of ion-pairing lifetime under such nanoscale confinement is substantially lower than its value in the bulk. It becomes still lower when aqueous mixtures of ionic liquid electrolytes are used.

How Does the P7C3-Series of Neuroprotective Small Molecules Prevent Membrane Disruption?

Molecular dynamics (MD) simulations are conducted to suggest a mechanism of action for the aminopropyl dibromocarbazole derivative (P7C3) small molecule, which protects neurons from apoptotic cell death. At first, the influence of embedded Aβ stacks on the structure of membrane is studied. Then, the effect of P7C3 molecules on the Aβ fibril enriched membrane and Aβ fibril depleted membrane (when Aβ fibrils are originally dissolved in the aqueous phase) are evaluated.

Novel curcumin-based pyrano[2,3-d]pyrimidine anti-oxidant inhibitors for α-amylase and α-glucosidase: Implications for their pleiotropic effects against diabetes complications.

Curcumin (bis-α,β-unsaturated β-diketone), the chief constituent of turmeric plant (Curcuma longa), plays significant role in prevention of various diseases including diabetes. The research objective in the current study was to synthesize novel anti-diabetic curcumin derivatives with inhibitory properties against α-amylase (α-Amy) and α-glucosidase (α-Gls), as these two carbohydrate-hydrolysing enzymes are known to be important molecular targets for attenuation of postprandial hyperglycemia. The curcumin-based pyrano[2,3-d]pyrimidine derivatives were synthesized in the presence of curcumin, barbituric acids and aldehydes, using a multi-component reaction (MCR).

Studies of structural, dynamical, and interfacial properties of 1-alkyl-3-methylimidazolium iodide ionic liquids by molecular dynamics simulation.

Bulk and surface properties of the ionic liquids 1-alkyl-3-methyl-imidazolium iodides ([C(n)mim]I) were simulated by classical molecular dynamics using all atom non-polarizable force field (n = 4, butyl; 6, hexyl; 8, octyl). The structure of ionic liquids were initially optimized by density functional theory and atomic charges obtained by CHELPG method. Reduction of partial atomic charges (by 20% for simulation of density and surface tension, and by 10% for viscosity) found to improve the accuracy, while a non-polarizable force field was applied.

The extent of molecular orientation at liquid/vapor interface of pyridine and its alkyl derivatives by molecular dynamics simulation.

In this paper, molecular dynamics simulation was performed to investigate the liquid∕vapor interfacial structure of neat polar liquids. Large-scale ensembles of liquid pyridine and its alkyl derivatives, 4-methylpyridine and 4-ethylpyridine, were simulated by classical molecular dynamics at 298 K. For the liquid system of low polarity, the surface density profile of the atoms meet exactly at the middle of interfacial region, and atoms of hydrophobic nature can be hardly discriminated from hydrophilic ones in either vapor or liquid sides.