Synthesis and Antibacterial Activity of Novel Triazolo[4,3-a]pyrazine Derivatives

Infectious diseases pose a major challenge to human health, and there is an urgent need to develop new antimicrobial agents with excellent antibacterial activity. A series of novel triazolo[4,3-a]pyrazine derivatives were synthesized and their structures were characterized using various techniques, such as melting point, 1H and 13C nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. All the synthesized compounds were evaluated for in vitro antibacterial activity using the microbroth dilution method. Among all the tested compounds, some showed moderate to good antibacterial activities against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli strains. In particular, compound 2e exhibited superior antibacterial activities (MICs: 32 μg/mL against Staphylococcus aureus and 16 μg/mL against Escherichia coli), which was comparable to the first-line antibacterial agent ampicillin. In addition, the structure-activity relationship of the triazolo[4,3-a]pyrazine derivatives was preliminarily investigated.

Crystal structure of 1-anilino-5-methyl-1H-1,2,3-triazole-4-carb-oxy-lic acid monohydrate

The water mol­ecule connects the mol­ecules in the crystal packing. The crystal structure exhibits N—H⋯O, O—H⋯O and O—H⋯N inter­actions, resulting in the formation of a three-dimensional framework.

In the mol­ecular structure of the title compound, C₁₀H₁₀N₄O₂·H₂O, the angle between the triazole and arene rings is 87.39 (5)°. The water of crystallization connects the mol­ecules in the crystal packing. The crystal structure exhibits N—H⋯O, O—H⋯O and O—H⋯N inter­actions, resulting in the formation of a three-dimensional framework. The inter­molecular inter­actions were identified and qu­anti­fied using Hirshfeld surface analysis.