İshak Bildirici

Further derivatives of 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid and their antibacterial activities

Compound 4, 5, 6, 7, and 8 were synthesized from 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carboxylic acid 1 as a starting material. The pyrazolo[4,3-d]oxazinone 4 was obtained from direct reaction of the acid 1 with hydroxylamine hydrochloride. Acid chloride 2 was converted easily into the new derivatives consisting of 1-(4-benzoyl-1,5-diphenyl-1H-pyrazol-3-oyl)-sulfamide 5 and 3,4-dibenzoyl-1,5-diphenyl-1H-pyrazole 6. The nitrile derivative 7 was obtained by dehydration of the amide 3 in a mixture of SOCl2 and Dimethylformamide (DMF). Cyclocondensation reaction of 7 with anhydrous hydrazine led to the formation of 7-aminopyrazolo[3,4-d]pyridazine 8 derivative. These new synthesized compounds evaluated for their antibacterial activities against Gram-positive and Gram-negative bacteria using the tube dilution method. The finding of antibacterial activity study showed that the sulfamide derivative 5 was the best compound of the series, exhibiting antibacterial activity against both Gram-positive and Gram-negative bacteria.

Synthesis and antibacterial activity of 4-benzoyl-1-(4-carboxy-phenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid and derivatives

A new 1H-pyrazole-3-carboxylic acid 2, along with hydrazono-pyridazinone 3, a by-product, and its derivatives 4–7 were synthesized and the structures confirmed by infrared (IR) and 1H and 13C nuclear magnetic resonance (NMR) data. These new compounds were evaluated for their antibacterial activities against Gram-positive and Gram-negative bacteria using the tube dilution method. The minimal inhibitory concentrations (MICs) experiments revealed that most compounds exerted inhibitor effects against Klebsiella pneumonia, Escherichia coli, Bacillus subtilus, and Xanthomonas compestris test microorganisms. Moreover, the results showed that the pyrazolo[3,4-d]pyridazine compounds were the best compounds of the series, exhibiting antibacterial activity against both Gram-positive and Gram-negative bacteria.

Unsymmetrical pyrazole-based new semiconductor oligomer: synthesis and optical properties

Poly(p-phenylene-1-(2,5-dimethylphenyl)-5-phenyl-1H-pyrazole-3,4-dicarboxy amide) (poly(PDPPD)) was synthesized from reactions of p-phenylene-diamine and 1-(2,5-dimethylphenyl)-5-phenyl-1H-pyrazole-3,4-dicarbonyl dichloride (monomer) by heating under solvent. This newly synthesized poly(PDPPD) was characterized by 1H, 13C-NMR, FT-IR, gel permeation chromatography (GPC). In addition, we investigated optical properties of the poly(PDPPD) containing the substituted pyrazole ring at different molarities. The average transmittance (Tavg) values of the poly(PDPPD) in the visible (V) region were higher than the Tavg values in the near-ultraviolet (NU) region. The Tavg values of the poly(PDPPD) in the NU and visible (V) region decreased with increasing molarity. The absorption band edge (Absbe) value of the poly(PDPPD) decreased with increasing molarity. It was observed that the optical band gap (Eg) of the poly(PDPPD) value decreased more with increasing molarity. The refractive index of the poly(PDPPD) decreased with increasing wavelength and decreasing molarity. The structure of the poly(PDPPD) in the lowest energy was optimized by DFT calculation and its HOMO–LUMO orbitals were plotted.

Synthesis and evaluation of aromaticity and tautomerization of pyrazolopyridazin(on)es

Aromaticity of pyrazolopyridazin(on)es was investigated using NICS(0), NICS(1), NICSzz(1), FIPC-NICS and HOMA aromaticity indexes and it was observed that aromaticity of pyridazin(on)es was amenable to aromaticity of pyrazole and vice versa. Some tautomeric forms of pyridazinone were analyzed and the localized orbital locator maps, electron density maps, Fuzzy, Laplacian, and Mayer bond order methods showed dominant form. Different substituents, amine, chlorine, phenyl, methyl, hydrogen, substituted-phenyl, etc. on both the rings were chosen to search out the substituent effect. Aromaticity of pyrazolopyridazin(on)es was searched out in detail for the first time.Graphical AbstractSynopsis: Aromaticity of Pyrazolopyridazine was calculated and the effect of bicyclic system on aromaticity was revealed. Furthermore, tautomerization of the same skeleton was investigated and the dominant tautomer was identified by means of aromaticity, bond order, and LOL map.