Ahmed Mkadmh

Antibacterial activities of novel nicotinic acid hydrazides and their conversion into N-acetyl-1,3,4-oxadiazoles

Synthesis of a series of novel N-acylhydrazones of nicotinic acid hydrazides 3a-j via condensation of nicotinic acid hydrazide 1 with the corresponding aldehydes and ketones is described. The series 3a-j was evaluated for in vitro antibacterial activity against two gram negative (Pseudomonas aeruginosa and Klebsiella pneumoniae) and two gram positive (Streptococcus pneumoniae and Staphylococcus aureus) bacteria. The zone of inhibition was measured using the disk diffusion method, and in vitro minimum inhibitory concentration indicating that compounds 3a and 3e were effective against P. aeruginosa with MICs of 0.220 and 0.195 μg respectively.

Enhancement of molecular polarizabilities by the push-pull mechanism; a DFT study of substituted benzene, furan, thiophene and related molecules

We report Density Functional Theory (DFT) studies of the dipole polarizabilities of benzene, furan and thiophene together with a number of substituted and related systems. All geometries were optimized (and characterized) at the B3LYP/6-311g(2d,1p) level of theory and polarizabilities then calculated with B3LYP/6-311++G(2d,1p). For the R-ring systems we find group polarizabilities in the order R = NO2 ∼ OCH3 ∼ CN ∼ CHO > NH2 > OH > H = 0. For systems R-ring-R, 〈α〉 differs little from the additivity model, with small positive and negative increments. For systems D-ring-A (where D and A are deactivating and activating groups) we find a positive enhancement to 〈α〉 over and above the value expected on the basis of pure additivity for all pairs A and D studied. This enhancement can be increased greatly by extending the length of the conjugated chain to D-ring-CH=CH-ring-A and D-ring-N=N-ring-A systems. Empirical models of polarizability such as AM1 agree badly with the DFT calculations in an absolute sense but give excellent statistical correlation coefficients. Calculated 〈α〉’s also agree well in a statistical sense with the molecular volumes calculated from molecular mechanics force fieldsAnalysis of the results in terms of the π electrons alone is not satisfactory.

Synthesis, antibacterial and QSAR evaluation of 5-oxo and 5-thio derivatives of 1,4-disubstituted tetrazoles.

A series of 1,4-disubstituted tetrazol-5-ones 3a, 5, 7, 12, 13 and 1,4-disubstituted tetrazol-5-thiones 3b, 9, 10 was synthesized and fully characterized by IR, MS, (1)H NMR and (13)C NMR. The series was evaluated for in vitro antibacterial activity against four Gram negative (Escherichia coli, Proteus mirabilis, Klebsiella pneumonia, and Pseudomonas aeruginosa) and three Gram positive (Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis) bacteria. The zone of inhibition was measured using the well-diffusion assay, and in vitro minimum inhibitory concentration (MIC) was determined by microbroth dilution assay. MIC values indicate that compounds exhibited a varied range (0.2-37 μg/mL) of antibacterial activity against the tested bacterial strains. Statistically significant QSAR models were developed by the simple linear regression analysis for the correlation of MIC with computed descriptors. The concluded cross validated regression factors are 0.953 and 0.986 for E. coli, and S. aureus, respectively.

Synthesis and semi-empirical sparkle PM6 study of substituted dithiophosphoric compounds of gadolinium(III)

Seven gadolinium(III) derivatives containing dialkyl and alkylene dithiophosphate chelating ligands [S2P(OR)2]3·2CH3CN (R = Et, n-Pr, n-Bu and Ph) and [S2POR′O]3·2CH3CN (R′ = CH2CMe2CH2, CH2CEt2CH2 and CMe2CMe2) have been synthesized. The metal complexes have been characterized by elemental analyzes, molecular weight determinations, IR, and UV–Visible spectroscopy. Microanalytical data revealed a 1 : 3 metal–ligand ratio in all complexes. Geometries were fully optimized at the semi-empirical sparkle PM6 level of theory using MOPAC2009 and geometrical structures and electronic properties of the complexes have been evaluated. The optimized geometries were confirmed to be minima on the potential energy surfaces through frequency calculations. Absorption spectra of the complexes have been calculated using ORCA2.9 package utilizing the predicted optimized wave functions. Linear and nonlinear static optical susceptibilities for all complexes were calculated at the same level of theory. The polarizability invariants were, in general, well correlated with the molecular volume and the number of carbons within the alkyl moieties. The largest electric properties were exhibited by the phenyl dithiophosphate complex.