Hacer Bayrak

Synthesis of some new 1,2,4-triazoles, their Mannich and Schiff bases and evaluation of their antimicrobial activities

4-Phenyl-5-pyridin-4-yl-4H-1,2,4-triazole-3-thiol (3) was obtained in basic media via the formation of 2-isonicotinoyl-N-phenylhydrazinecarbothioamide (2), and converted to some alkylated derivatives (4a,b) and Mannich base derivatives (5a-c). 2-[(4-Phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]acetohydrazide (7) that was obtained by using compound 3 as precursor in two steps was converted to thiosemicarbazide derivative (8), Schiff base derivatives (9) and 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-1,3,4-oxadiazole-2-thiol (10). Moreover, 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-3-{[(2-morpholin-4-ylethyl)amino]methyl}-1,3,4-oxadiazole-2(3H)-thione (11) was synthesized via reaction of compound 10 with 2-(4-morpholino)ethylamine. The treatment of compound 8 with NaOH gave 4-(4-methylphenyl)-5-{[(4-phenyl-5-pyridine-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-4H-1,2,4-triazole-3-thiol (12), while the acidic treatment of compound 8 afforded 5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio]methyl}-2(4-methylphenyl)-amino-1,3,4-thiadiazole (14). N-Methyl derivative of compound 14 and a Mannich base derivative of compound 12 were synthesized from the reactions of these precursors with methyl iodide and methyl piperazine, respectively. All newly synthesized compounds were screened for their antimicrobial activities. The antimicrobial activity study revealed that all the compounds screened showed good or moderate activity except compounds 3, 5c, 7, 9c, 9e, 9g, 9h, 11, and 13.

Synthesis of some new 1,2,4-triazoles starting from isonicotinic acid hydrazide and evaluation of their antimicrobial activities

5-Pyridin-4-yl-1,3,4-oxadiazole-2-thiol (2) was obtained from the reaction of isonicotinic acid hydrazide with carbon disulfide in basic media and converted into 4-amino-5-pyridin-4-yl-4H-1,2,4-triazole-3-thiol (5) by the treatment with hydrazine hydrate. The synthesis of 3 and 6 was performed from the reaction of 2 and 5 with ethyl bromide. The treatment of 5 with 4-fluorobenzaldehyde or indol-3-carbaldehyde resulted in the formation of 4-[(arylmethylene)amino]-5-pyridin-4-yl-4H-1,2,4-triazole-3-thiols (7a and 7b). The reactions of 2, 5 and 7a with some primary and secondary amines in the presence of formaldehyde afforded the corresponding Mannich bases, 4a, 4b, 9a-9c and 8. All newly synthesized compounds were screened for their antimicrobial activity. The antimicrobial activity study revealed that all the compounds screened showed good or moderate activity except compounds 2, 7a, 7b, 8 and 9b.

Cyclization of some carbothioamide derivatives containing antipyrine and triazole moieties and investigation of their antimicrobial activities

Acetohydrazide derivative containing both antipyrine and triazole nuclei (5) was obtained starting from ethyl hydrazinecarboxylate derivative (2) and 4-aminoantipyrine (1) by three steps. The treatment of compound 5 with CS(2) afforded the conversion of hydrazide function into 5-mercapto-1,3,4-oxadiazole ring leading to the formation of 7. Then, 7 gave the product containing triazolotriazine moiety (9) by the reaction with hydrazine hydrate. The synthesis of the compounds incorporating the 1,3,4-thiadiazole (10a-c), 1,2,4-triazole (11a-c) or 1,3-thiazole (12, 13) nucleus as third heterocycle was performed by the acidic or basic treatment of compounds 6a-c which were obtained from the reaction of 5 with several isothiocyanates, or by the condensation of 6a with two different phenacyl bromides, respectively. The antimicrobial activity study revealed that all the compounds showed good activities except 3-5.

Synthesis, aggregation and spectroscopic studies of novel water soluble metal free, zinc, copper and magnesium phthalocyanines and investigation of their anti-bacterial properties

In this study, novel phthalonitrile derivative (3) was synthesized by the reaction between 4-nitrophthalonitrile (2) and a triazole derivative (1) containing pyridine moiety. Crystal structure of compound (3) was characterized by X-ray diffraction. New metal free and metallo-phthalocyanine complexes (Zn, Cu, and Mg) were synthesized using the phthalonitrile derivative (3). Cationic derivatives of these phthalocyanines (5, 7, 9, and 11) were prepared from the non-ionic phthalocyanines (4, 6, 8, and 10). All proposed structures were supported by instrumental methods. The aggregation behaviors of the phthalocyanines (4-11) were investigated in different solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform and water. Water soluble cationic Pcs (5, 7, 9, and 11) aggregated in water and sodium dodecyl sulfate was used to prevent the aggregation. The second derivatives of the UV-Vis spectra of aggregated Pcs were used for analyzing the Q and B bands of aggregated species. Thermal behaviors of the phthalocyanines were also studied. In addition, anti-bacterial properties of the phthalocyanines were investigated. We used four gram negative and two gram positive bacteria to determine antibacterial activity of these compounds. Compound 7 has the best activity against the all bacteria with 125μg/mL of MIC value. Compounds 4, 6, and 10 have the similar effect on the bacteria with 250μg/mL of MIC value.

Syntheses and biological activities of new hybrid molecules containing different heterocyclic moieties.

4‐Aryl‐5‐(pyridin‐3‐yl)‐4H‐1,2,4‐triazole‐3‐(thi)oles 5–7, obtained starting from nicotinic acid hydrazide were converted to the corresponding Mannich bases 12–24 by the reaction with several heterocyclic amines in the presence of formaldehyde. The synthesis of S‐alkylated compounds 8–11 was performed from the reaction of the corresponding triazol‐5‐thioles with various alkyl halides. The condensation of carbo(thio)amides 2–4 with 4‐chlorophenacyl bromide afforded the corresponding 1,3‐thia(oxa)zol‐2(3H)‐ylidene]pyridine‐3‐carbohydrazides 25–27. 1,3‐Thia(oxa)zolidine derivatives 28–30 were obtained from the cyclization reaction between compounds 2–4 and ethyl bromoacetate. All newly synthesized compounds were screened for their antimicrobial, antiurease, and antilipase activities. The biological activity studies revealed that all the compounds screened showed good or moderate antimicrobial, antiurease, and/or antilipase activity.

Synthesis and antimicrobial activity of new piperazine-based heterocyclic compounds

Abstract The hydrazide 5, that was obtained from 1-(4-fluorophenyl)piperazine (1), was converted to the corresponding carbothioamides 6a–c by the reaction with alkyl(aryl) isothiocyanates. The synthesis of conazole analogs 10a–f was performed via the intermediary of triazoles 7a–c. The condensation of triazoles 7a–c with several heterocyclic amines in the presence of formaldehyde afforded the corresponding N-aminoalkylated triazoles 11–14. The effect of different catalysts and solvents on conventional and microwave (MW)-prompted reactions was examined. The synthesized compounds were screened for their antimicrobial activities.

Microwave-assisted and conventional synthesis of novel antimicrobial 1,2,4-triazole derivatives containing nalidixic acid skeleton

Abstract Carbothioamides 4a,b, obtained from nalidixic acid, were converted to the corresponding 1,3-thiazolidine derivatives 5a,b by cyclocondensation with 2-bromo-1-(4-chlorophenyl)ethanone. Treatment of 4a,b with base afforded 1,2,4-triazoles 6a,b. The synthesis of 1,3-oxazolidine 7 was performed by the reaction of compound 4a with ethyl bromoacetate. Treatment of 4a with acid produced 1,3,4-thiadiazole 8. The reaction of compounds 6a and 6b with several heterocyclic amines in the presence of formaldehyde gave the corresponding Mannich bases 9–15 containing various pharmacophore groups. Conventional and microwave-assisted methods were used for the synthesis. The effect of an acid catalyst on Mannich reactions was investigated. The structures of the newly synthesized compounds were elucidated on the basis of 1H NMR, 13C NMR, FTIR, EIMS techniques, and elemental analysis. All compounds were screened for their antimicrobial activity.

Design and synthesis of some azole derivatives as potential antimicrobial agents

Syntheses of 1,2,4-triazol-3-ones, 4a, 4b, and 5 were performed starting from ester ethoxycarbonylhydrazones (1a, 1b) that were reported earlier. The treatment of triazole derivatives, 4a, 4b, and 5 with several sulfonyl halides produced the corresponding sulfonamides, 6–10. Syntheses of carbo(thio)amides, 15, 17, and 18 were carried out by the treatment of (substituted)phenyliso(thio)cyanates with hydrazides 13, 14 which were obtained starting from 4a and 5 by two steps. Cyclization of compounds 15 and 17 in basic media resulted in the conversion of carbo(thio)amide side chain to 5-oxo- or 5-mercapto-1,2,4-triazole ring. Cyclocondensation of 17 with ethyl chloroacetate and 4-nitrophenacylbromide gave 1,3-thiazolidin, 20 and 1,3-thiazol 21, derivatives, respectively. Newly synthesized compounds were screened for their antimicrobial activities, and some of them displayed activity against the test microorganisms. Then the highest activity was observed for compounds 6 and 7 carrying cyclic sulfonamide function beside 1,2,4-triazole nucleus.

Determination of Au(III) and Pd(II) ions by flame atomic absorption spectrometry in some environmental samples after solid phase extraction

ABSTRACT A simple and sensitive solid phase extraction method was developed for simultaneous separation and preconcentration of gold and palladium ions with N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridine-4-yl-4H-1,2,4-triazol-3-yl)thio]acetyl}hydrazine carbo thioamide complex on Amberlite XAD-1180 resin before their determination by flame atomic absorption spectrometry. Some analytical parameters such as HNO3 concentration of the sample solution, amount of complexing agent, sample volume, eluent type and volume, effects of foreign ions and adsorption capacity of the resin were investigated for quantitative recovery of gold and palladium ions. The effects of some anions and cations were also examined. Under optimum conditions, the detection limits for gold and palladium ions were found to be 0.29 and 0.19 μg L−1, respectively. The preconcentration factor for gold and palladium was 250. After being validated by standard addition and analysis of standard reference material, the procedure was successfully applied to the analysis of sea and stream water, anodic slime, gold ore, soil and electronic waste.

SOLID PHASE EXTRACTION OF Cd(II) AND Pb(II) IONS BY A NEW CARBOTHIOAMIDE DERIVATIVE

An effective, simple, low cost and accurate sorption–spectrophotometric platform for the extractions and subsequent quantifications of Cd(II) and Pb(II) ions in food and environmental samples has been described in this dissertation. The separation and preconcentration of the analyte ions were accomplished by solid phase extraction method based on the adsorption of their N–(4–methylphenyl)–2–{[(4–phenyl–5–pyridin–4–yl–4H–1,2,4–triazol–3–yl)thio]acetyl} hydrazinecarbothioamide (MFPTAHK) complex on Amberlite XAD–8 resin in a mini column. The developed method was systematically investigated in different set of experimental parameters that influence the separation and preconcentration of Cd(II) and Pb(II) ions. The precision of the method was determined by reproducibility studies and expressed as relative standard deviations (RSD %) which were less than 4% for both analyte ions. The limits of detections (LODs) for Cd(II) and Pb(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 0.31 µg L–1 and 0.86 µg L–1, respectively. The developed SPE procedure was utilized for the simultaneous extraction and determinations of Cd(II) and Pb(II) ions levels in rice, cracked wheat and red lentil as food samples and various water samples.