Synthesis, crystal structures, spectroscopic analysis and DFT calculations of 2-ethoxy-1-naphtaldehyde and (E)-N-((2-ethoxynaphthalen-1-yl)methylene)-3-methylaniline

Derivatives of pyridine and thiazole hybrid: Synthesis, DFT, biological evaluation via antimicrobial and DNA cleavage activity

A novel series of the 2-pyridine substituted 3a-e and 4-pyridine substituted 4a-e thiazole derivatives were synthesized, characterized, and evaluated for the biological activity. Crystallographic parameters and inter- and intramolecular interactions of 3a and 3c single crystals were examined through XRD analysis. The chemical reactivity potentials of the compounds were evaluated, by comparing with a theoretical approach based on DFT. The biological activity properties of synthesized compounds were determined by antimicrobial activity with Gram positive, Gram negative, Yeast via minimal inhibitory concentration (MIC) method and DNA cleavage activity studies. The most obvious findings to emerge from this study are that on the basis of both biological activity and chemical reactivity 4-pyridine thiazole hybrid compounds 4a-e showed more potent activity than 3a-e. In general, the antimicrobial activity of synthesized compounds follows the Bacillus cereus > Staphylococcus aureus > Candida albicans > Escherichia coli > Pseudomonas aeruginosa. The most potent compound 4c (MIC values 0.02 mM) exhibited antimicrobial activity against Staphylococcus aureus and Bacillus cereus. Furthermore, this compound has a good electrophilicity index value (4.56 eV).

2,2′-[(Disulfanediyl)bis{5-[(1E)-(2-hydroxybenzylidene)amino]-1,3-thiazole-4,2-diyl}]diphenol: synthesis, crystal structure and calculation of molecular hyperpolarizability

The title Schiff base compound {systematic name: 2-[5-[(E)-(2-hydroxybenzylidene)amino]-4-(2-{5-[(E)-(2-hydroxybenzylidene)amino]-2-(2-hydroxyphenyl)-1,3-thiazol-4-yl}disulfanyl)-1,3-thiazol-2-yl]phenol}, C32H22N4O4S4, incorporating a disulfanediyl (dithio) linkage, was obtained from the condensation reaction between two equivalents of salicylaldehyde and one equivalent of dithiooxamide in dimethylformamide, and was characterized by elemental analysis, IR spectroscopic analysis and single-crystal X-ray diffraction. A one-dimensional chain is formed along the b axis via double intermolecular C—H...S hydrogen bonds. The HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies and some related molecular parameters were calculated at the B3LYP/6-311G(d,p) level of theory. The molecular hyperpolarizability was also calculated.