Synthesis of new 1,2,4-triazole compounds containing Schiff and Mannich bases (morpholine) with antioxidant and antimicrobial activities

Abstract

Compound 2 was synthesized by reacting CS₂/KOH with compound 1. The treatment of compound 2 with hydrazine hydrate produced compound 3. Then, compound 3 was converted to Schiff bases (4a–d) by the handling with several aromatic aldehydes. The treatment of triazole compounds 4a–d containing Schiff base with morpholine gave compounds 5a–d. All compounds were tested for their antioxidant and antimicrobial activities. The antioxidant test results of DPPH• radical scavenging and ferric reducing/antioxidant power methods showed good antioxidant activity. The triazole-thiol (3) was the most active, and the effect of the substituent type of the thiophene ring on the activity was same for both Schiff bases (4a–d) and Mannich bases (5a–d). Among the newly synthesized triazole derivatives, the Schiff base 4d and the Mannich base 5d carrying nitro substituent on the thiophene ring showed promising antibacterial and antifungal activity, with lower MIC values than the standard antibacterial ampicillin.

Keywords:

• Antimicrobial and antioxidant activities
• Mannich bases
• morpholine
• 1,2,4-triazole-thiol
• Schiff bases

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article. This study was supported by grants from Karadeniz Technical University and Scientific and Technological Research Council of Turkey (TÜBİTAK-114Z582).

Supplementary materials online only – For review only at proofing stage.

NMR spectra of the new compounds are provided as the supplementary material.