Corrosion Inhibition Properties of Phenyl Phthalimide Derivatives against Carbon Steel in the Acidic Medium: DFT, MP2, and Monte Carlo Simulation Studies.

The effectiveness of phenyl phthalimide and its derivatives at preventing corrosion of carbon steel has been tested experimentally using gravimetric and electrochemical measurements. However, experimental studies have not thoroughly explained the structural patterns and coating mechanisms of phenyl phthalimide and its derivatives during corrosion inhibition. In this study, the density functional theory (DFT), ab initio MP2, and Monte Carlo simulation are applied to study phenyl phthalimide (PP) and its derivatives as corrosion inhibitors of carbon steel. The geometry, quantum parameters, and reactive site of the inhibitors were determined by DFT and ab initio MP2 methods. The real environment conditions of corrosion inhibition in the solution phase can be replicated by the Monte Carlo simulation. The corrosion inhibition efficiency of phthalimide derivatives is PP-OCH3 > PP-CH3 > PP-H > PP-Cl > PP-NO2. The theoretical study is consistent with previously reported experimental results.

Green Synthesis of Silver Nanoparticles Coated by Water Soluble Chitosan and Its Potency as Non-Alcoholic Hand Sanitizer Formulation.

The synthesis of silver nanoparticles using plant extracts, widely known as a green synthesis method, has been extensively studied. Nanoparticles produced through this method have applications as antibacterial agents. Bacterial and viral infection can be prevented by use of antibacterial agents such as soap, disinfectants, and hand sanitizer. Silver nanoparticles represent promising hand sanitizer ingredients due to their antibacterial activity and can enable reduced use of alcohol and triclosan. This study employed silver nanoparticles synthesized using Kepok banana peel extract (Musa paradisiaca L.). Nanoparticle effectiveness as a hand sanitizer can be enhanced by coating with a biocompatible polymer such as chitosan. The characterization of silver nanoparticles was conducted using UV-Vis, with an obtained peak at 434.5 nm. SEM-EDX analysis indicated nanoparticles with a spherical morphology. Silver nanoparticles coated with chitosan were characterized through FTIR to verify the attached functional groups. Gel hand sanitizers were produced using silver nanoparticles coated with different chitosan concentrations. Several tests were undertaken to determine the gel characteristics, including pH, syneresis, and antibacterial activity. Syneresis leads to unstable gels, but was found to be inhibited by adding chitosan at a concentration of 2%. Antibacterial activity was found to increase with increase in chitosan concentration.

Cis-2 and trans-2-eisocenoic fatty acids are novel inhibitors for Mycobacterium tuberculosis Protein tyrosine phosphatase A.

Small protein tyrosine phosphatase (PtpA) of Mycobacterium tuberculosis is attributed to the development of latent tuberculosis infection, and hence bocomes an interesting target for drug development. In this communication, inhibition of PtpA by naturally occurring fatty acids cis-2 and trans-2-eicosenoic acid is investigated. Mtb PtpA was heterologously expressed in Escherichia coli, and the activity of PtpA was inhibited by cis-2 and trans-2 eicosenoic fatty acids. Both compunds showed strong inhibition of PtpA activity with IC50 at low micromolar concentration. As comparison, trans-11-eicosenoic acid only slightly inhibit PtpA. In silico analysis confirmed the inhibition of PtpB by cis-2-eicosenoic acid by formation of several hydrogen bonds. These findings show that cis-2 and trans-2 eicosenoic fatty acids are potential candidates for latent tuberculosis inhibitors.

Remarkable conformational flexibility of aqueous 18-crown-6 and its strontium(II) complex-ab initio molecular dynamics simulations.

Ab initio QMCF-MD simulations of aqueous 18-crown-6 (18C6) and strontium(II)-18-crown-6 (18C6-Sr) were performed to gather insight into their hydration properties. Strongly different characteristics were found for the two solutes in terms of structure and dynamics such as H-bonding. They, however, have in common that their backbone shows high flexibility in aqueous medium, adopting structures significantly differing from idealized gas phase geometries. In particular, planar oxyethylene units stable in the picosecond range occurred in 18C6, while the strontium complex readily exhibits a bent structure. Detailed analysis of this high flexibility was done via two dimensional root mean square deviation plots as well as the evolution of dihedral angles and angles within the simulation trajectory. The vibrational spectra obtained from the QMCF-MD simulations are in excellent agreement with experimental data and show a pronounced blueshift upon complexation of the strontium(II) ion in 18C6.