The following Schiff bases have been synthesized: (1) 4-[(2-chlorobenzylidene)amino]benzoic acid [JP1], (2) 4-[(furan-2-ylmethylene)amino]benzoic acid [JP2], (3) 4-[(3-phenylallylidene)amino]benzoic acid [JP3], (4) 4-[(2-hydroxybenzylidene)amino]benzoic acid [JP4], (5) 4-[(4-hydroxy-3-methoxybenzylidene)amino]benzoic acid [JP5] and (6) 4-[(3-nitrobenzylidene)amino]benzoic acid [JP6].They were screened as potential antibacterial agents against a number of medically important bacterial strains. The antibacterial activity was studied against A. faecalis ATCC 8750, E. aerogenes ATCC 13048, E. coli ATCC 25922, K. pneumoniae NCIM 2719, S. aureus ATCC 25923, P. vulgaris NCIM 8313, P. aeruginosa ATCC 27853 and S. typhimurium ATCC 23564. The antibacterial activity was evaluated using the Agar Ditch method. The solvents used were 1,4-dioxane and dimethyl sulfoxide. Different effects of the compounds were found in the bacterial strains investigated and the solvents used, suggesting, once again, that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. In the present work, 1,4-dioxane proved to be a good solvent in inhibiting the above stated bacterial strains.

Schiff bases derived from 4-aminoantipyrine and vanillin were evaluated for their potential as antibacterial agents against some Gram positive and Gram negative bacterial strains. The antibacterial activity was studied against P. pseudoalcaligenes ATCC 17440, P. vulgaris NCTC 8313, C. freundii ATCC 10787 E. aerogenes ATCC 13048, S. subfava NCIM 2178 and B. megaterium ATCC 9885. The determination of the antibacterial activity was done using the Agar Ditsh method. The Schiff bases produced were: (1) 4-(4-hydroxy 3-methoxybenzylideneamino) -1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one [VV1]; (2) 4-(benzylideneamino) -1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one [VY2]); (3) 4-[(furan-3-ylmethylene) amino ]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one [VY3]?; (4) 4-(4-methoxybenzylideneamino) -1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one [VY4]?; (5) 2-methoxy-4-[(4-methoxyphenylimino) methyl ]phenol [VY5]; (6) 4-[(2,4-dimethylphenylimino) methyl]-2-methoxyphenol [VY6]); (7) 2-methoxy-4-(naphthalene-1-yliminomethyl) phenol [VY7]?and (8) 4-[(4-hydroxy-3-methoxybenzylidene)amino]-N-(5-methylisoxazol 3-yl)benzenesulfonamide [VY8]. The antibacterial activity was evaluated in two polar solvents, DMSO and DMF. The Schiff bases derived from vanillin as the central molecule with 2,4-dimethylaniline and sulphamethoxazole as the side chain in DMSO effectively inhibited the investigated bacteria and appear to be promising antimicrobial agents.

This paper reports infrared absorption intensities of liquid methanol at 25°C between 8000 and 2 cm−1. Measurements were made by attenuated total reflection spectroscopy by four different workers between 1984 and 1991, with the use of CIRCLE cells of two different lengths and with several different alignments of the cell in the instrument. Steps were taken to ensure that as few parameters as possible remained unchanged throughout the series of measurements, to try to reveal systematic errors. The reproducibility was better than ±2.5% in regions of significant absorption. In order to allow comparison between different methods, results of all methods were converted to real and imaginary refractive index spectra. Measurements were also made by transmission spectroscopy in regions of weak absorption, with results that agreed excellently with those from ATR. The ATR and transmission results were combined to give a spectrum between 7500 and 350 cm−1. This spectrum agreed excellently with literature results from 350 to 2 cm−1, and the two sets of measurements were combined to yield a spectrum from 7500 to 2 cm−1. The imaginary refractive index was arbitrarily set to zero between 7500 and 8000 cm−1, where it is always less than 2 × 10−6, in order that the real refractive index can be calculated below 8000 cm−1 by Kramers-Kronig transform. The results are reported as graphs and as tables of the real and imaginary refractive indices between 8000 and 2 cm−1, from which all other infrared properties of liquid methanol can be calculated. The accuracy is estimated to be ±3% below 5000 cm−1 and ±10% above 5000 cm−1 for the imaginary refractive index and better than ±0.5% for the real refractive index. To obtain molecular information from the measurements, one calculates the imaginary molar polarizability spectrum, [Formula: see text] vs. [Formula: see text], under the Lorentz local field assumption, and the area under [Formula: see text] bands is separated into contributions from different vibrations under several approximations. Much accuracy is lost in this process. The changes of the dipole moment during normal vibrations, and during OH, CH, and CO bond stretching and COH torsional motion, are presented.

Two Schiff bases were synthesized from raceacetophenone: 1) ADS1 4-ethyl-6-{(E)-1-[(3-nitrophenyl)imino]ethyl}benzene-1,3-diol and 2) ADS3 4-ethyl-6-[(E)-1-{(2-nitrophenyl)imino]ethyl}benzene-1,3-diol. Then their metal complexes were formed. The metals selected for the preparation of complexes were copper, nickel, iron and zinc. Hence, in total 8 metal complexes were synthesized and screened for antibacterial activity against some clinically important bacteria, such as Pseudomonas aeruginosa, Proteus vulgaris, Proteus mirabilis, Klebsiella pneumoniae and Staphylococcus aureus. The in vitro antibacterial activity was determined by the Agar Ditch technique using DMF (polar) and 1,4-dioxane (non polar) as solvents. The Schiff bases showed greater activity than theirmetal complexes; themetal complexes showed differential effects on the bacterial strains investigated and the solvent used, suggesting that the antibacterial activity is dependent on the molecular structure of the compound, the solvent used and the bacterial strain under consideration. The Schiff base ADS3 in the polar solvent DMF showed better antibacterial activity towards the investigated bacterial strains. Amongst the four metals, Zn showed the best antibacterial activity followed by Fe in 1,4-dioxane while Ni followed by Zn and Fe showed the best antibacterial activity in DMF. P. vulgaris was the most resistant bacteria.

The solubility data of 5-amino salicylic acid in methanol, ethanol, carbon tetrachloride, and tetrahydrofuran (THF) at various temperatures were measured by gravimetrical method from (293.15 to 313.15) K under atmospheric pressure, and the solubility data were correlated as a function of temperature. The order of solubility is THF > carbon tetrachloride > ethanol > methanol. Further, some thermodynamic parameters such as enthalpy, Gibb’s energy, and entropy have also been evaluated for the dissolution process. It is observed that enthalpy and entropy are positive, whereas the Gibb’s energy of activation is negative for all of the four solvents. The negative Gibb’s energy suggests the spontaneous nature of dissolution process, whereas positive enthalpy indicates endothermic dissolution of compounds. The positive entropy is due to favorable dissolution in the studied solvents.