New dinuclear copper(I) metallacycles containing bis-Schiff base ligands fused with two 1,2,4-triazole rings: Synthesis, characterization, molecular structures and theoretical calculations

Structural, vibrational spectroscopy, molecular docking, DFT studies and antibacterial activity of (E)-N1-(3-chlorobenzylidene)benzene-1,4-diamine

In this work, (E)-N1-(3-chlorobenzylidene)benzene-1,4-diamine (CBD) compound was synthesized with good yield. The spectral studies were recorded by FT-IR, FT-Raman, NMR and UV-Vis to determine structural parameters. The geometrical parameters were optimized using DFT calculations at 6-311++G(d,p) basis set. The calculated structural parameters of the molecule were in line with the experimental data. The molecular orbitals of the compound were investigated through highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) analysis. The hyper conjugative interaction energy E(2) along with donor, acceptor electron densities (EDs) were determined by natural bond orbital (NBO) analysis. The molecular electrostatic potential (MEP), mulliken atomic charges, non-linear optical (NLO) properties and potential energy surface (PES) scan were also calculated. The 1H and 13C NMR chemical shifts calculated using Gauge invariant atomic orbital (GIAO) method were compared with the experimental NMR chemical shifts. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were carried out to characterise the thermal behaviour and stability of CBD molecule. In addition, PreADMET tool was also used to estimate ADME and Toxicity of CBD compound. The compound screened against four pathogens two gram positive and two gram negative had shown good anti-bacterial behaviour. The molecular docking studies executed against anti-bacterial target topoisomerase DNA gyrase enzyme (2XCT) emphasized good binding behaviour over the standard drug.Communicated by Ramaswamy H. Sarma.

Unprecedented palladium(ii) complex containing dipodal 1,3,4-thiadiazole derivatives: synthesis, structure, and biological and thermal investigations

The synthesis and characterization of a novel palladium complex based on a bioactive 1,3,4-thiadiazole derivative has been investigated. This novel complex showed excellent antibacterial activity and its thermolysis resulted in PdO nanoparticles.

Synthesis and characterization of Schiff bases NBBA, MNBA and CNBA

Three Schiff base compounds, N¹,N²-bis(3-nitrobenzylidene)phenylene diamine (NBBA), 2-methyl-N-(3-nitrobenzylidene)aniline (MNBA) and N-(2-chlorobenzylidene)-4-nitroaniline (CBNA) were synthesized, characterised and applied for the first time as potential mild steel (MS) corrosion inhibitors in 1 M HCl at 30 °C. Fourier transform infra-red (FTIR), ¹H, ¹³C Nuclear magnetic resonance (NMR) and Mass spectrometry (MS) were used for the characterisation of the compounds. The electrochemical studies and evaluation of corrosion inhibition potency were achieved using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. Density functional theory (DFT) calculations were further employed to describe the electronic distribution on the molecules and potential sites that aided corrosion inhibition. The results of the employed characterisation techniques confirmed the proposed structures of the compounds with the MS revealing the exact molecular mass of the compounds. Electrochemical results showed that the trend in inhibition efficiency of the three compounds was in the order: MNBA > NBBA > CBNA. MNBA recorded the highest inhibition efficiency at 100 ppm. Corrosion kinetics of the set of inhibitors was found to prefer the Langmuir adsorption isotherm with both physisorption and chemisorption mechanisms as revealed by ΔG values. In an effort to develop efficient corrosion inhibitors with non-toxic effect, low cost and multiple adsorption centres, these Schiff bases are presented.

Adsorption Mechanism of 4-Amino-5-mercapto-1,2,4-triazole as Flotation Reagent on Chalcopyrite

A novel compound 4-amino-5-mercapto-1,2,4-triazole was first synthesized, and its selective adsorption mechanism on the surface of chalcopyrite was comprehensively investigated using UV-vis spectra, zeta-potential, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy measurements (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and first principles calculations. The experimental and computational results consistently demonstrated that AMT would chemisorb onto the chalcopyrite surface by the formation of a five-membered chelate ring. The first principles periodic calculations further indicated that AMT would prefer to adsorb onto Cu rather than Fe due to the more negative adsorption energy of AMT on Cu in the chalcopyrite (001) surface, which was further confirmed by the coordination reaction energies of AMT-Cu and AMT-Fe based on the simplified cluster models at a higher accuracy level (UB3LYP/Def2-TZVP). The bench-scale results indicated that the selective index improved significantly when using AMT as a chalcopyrite depressant in Cu-Mo flotation separation.