Synthesis, characterization, antimicrobial, antioxidant activities, and in silico study of new azo disperse dyes containing pyrazole and pyrazolo[1,5-a]pyrimidine rings

New N,N-dimethyl-N'-(5-oxo-4-(aryldiazenyl)-2,5-dihydro-1H-pyrazol-3-yl)formimidamide 5a-c are formed by reaction of 5-amino-1H-pyrazol-3(2H)-one derivatives 4a-c with N,N-dimethylformamide dimethyl acetal (DMF-DMA). Compounds 5a-c serve as excellent precursors for the synthesis of new disazo pyrazole disperse dyes, When refluxed with hydrazine hydrate or active methylene reagents 8a,b, leading to N''-(3-hydroxy-4-(arylaza)-1H-pyrazol-5-yl)formimidohydrazide 7a-c or pyrazolo[1,5-a]. pyrimidines 11a–e. In vitro studies were carried out to evaluate antioxidant properties of the produced compounds in comparison to standard, BHT. The results indicated that all the compounds exhibited varying levels of antioxidant activity at different doses. Compound (7b) exhibited an IC50 value comparable to that of BHT, while the other compounds demonstrated varying levels of activity and IC50 values in comparison to BHT. Regarding antimicrobial activity, compounds 7a, 7b and 11c exhibited antibacterial efficiency against Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis with inhibition zone diameters of 14.33, 12.33, and 12.33 mm, respectively. In silico study of eleven pyrazole compounds with S. aureus 2XCT demonstrated strong hydrogen bonds, short distance interactions, and the highest binding energies were displayed by compounds 5b and 11a with binding energy of -6.6 and -6.2 kcal/mol, respectively. KEY WORDS: Pyrazoles, DMFDMA, Antimicrobial, Antioxidant, Molecular docking, Disperse dyes, Pyrazolo[1,5-a]pyrimidines Bull. Chem. Soc. Ethiop. 2025, 39(7), 1411-1424. DOI: https://dx.doi.org/10.4314/bcse.v39i7.13