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The Schiff base, 4-[3-(4-methoxy-phenyl)-allylideneamino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (TPMC/AAP) was synthesized by the condensation of 4-aminoantipyrine (4-amino-1,5-dimethyl-2-phenylpyrazole-3-one) and trans-para-methoxycinnamaldehyde (trans-3,4-methoxyphenyl-2-propenal) in dry methanol at 75 °C. The compound was characterized using elemental microanalysis, IR, NMR, UV spectroscopies and single-crystal X-ray crystallography. The X-ray structure determination shows that the Schiff base, (TPMC/AAP) is orthorhombic with the Pbca space group. The anti-microbial screening of the compound was carried out with Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudemonas aeruginosa, Candida albicans and Aspergillus niger using agar well diffusion method. The Schiff base possesses significant antimicrobial activity. The minimum inhibitory concentration (MIC) of the compound was also determined and the activity was compared with that of conventional drugs ciprofloxacin and ketoconazole. The compound (TPMC/AAP) showed varying activity against the cultured bacteria and fungi used. To complement the experimental data, density functional theory (DFT) was used to have deeper understanding into the molecular parameters and infrared spectra of the compound. [ABSTRACT FROM AUTHOR]

[Display omitted] • All possible tautomers of hydantoin interconversions were investigated. • DFT B3LYP-D3(BJ)/aug-cc-pVTZ method was used to account for dispersion corrections. • Explicit water and ethanol have a catalytic effect on specific energy barriers. • Binding energies for hydantoin bound to water or ethanol were calculated. Hydantoin exhibits tautomerism and the interconversion among the tautomers was studied using theoretical methods in the gas phase and solvents (water or ethanol). The implicit solvation as well as one explicit solvent molecule with water or ethanol were investigated. The functional used was B3LYP-D3(BJ) and the basis set for all atoms was aug-cc-pVTZ. The results indicate that the electronic energy barriers in the gas phase and implicit solvation are in the range 50–90 kcal mol−1. However, explicit water is found to have a catalytic effect as the electronic energy barriers are lowered to 18–30 kcal mol−1. Explicit ethanol lowers the electronic energy barriers further by about 2 kcal mol−1. This study should be beneficial for the rational design and experiments involving hydantoin and water or ethanol as solvents. [ABSTRACT FROM AUTHOR]

The reaction of the rhenium(V) complex cis-[ReO2I(PPh3)2] with 2-aminothiophenol (H2atp), benzene-1,2-dithiol (H2tdt) and 2-hydroxybenzenethiol (H2otp) led to the formation of the rhenium(III) complexes [Re(Hatp)(ibsq)2]·OPPh3, [Re(sbsq)3]·OPPh3 and [Re(obsq)3]·OPPh3 (ibsq=2-iminothiobenzosemiquinonate, sbsq=1,2-dithiobenzosemiquinonate, obsq=2-hydroxothiobenzosemiquinonate) respectively. These paramagnetic complexes were characterized by single crystal X-ray crystallography, 1H NMR spectrometry, IR and electronic spectroscopy, and cyclic voltammetry. To complement the experimental data, density functional theory (DFT) and time-dependent DFT were successfully used to investigate the structural, molecular, infrared and electronic spectra of these three complexes. [ABSTRACT FROM AUTHOR]