Novel 1,3-Diazepines as Nontoxic Corrosion Inhibitors.

Nitrogen-containing heterocyclic compounds are among the most effective corrosion inhibitors, primarily acting through adsorption by donating electron pairs to metallic surfaces. While benzodiazepines and other 1,4- and 1,5-diazepine derivatives have demonstrated inhibitory activity, 1,3-diazepan-2-ylidenes remain unexplored in the literature. In the present study, ketene dithioacetals were employed as building blocks for the synthesis of a novel series of 2-substituted 1,3-diazepines. Their corrosion inhibition efficiency was systematically evaluated, alongside in silico predictions of toxicity risks and in vitro cytotoxicity assays against the MDA-MB-231 human breast adenocarcinoma cell line, the A549 human lung carcinoma cell line, the TOV-21G human ovarian adenocarcinoma cell line, and the WI-26VA4 human lung fibroblast cell line. The synthesized compounds exhibited significant corrosion inhibition performance, while in silico analyses indicated no relevant toxicity risks, findings further supported by low cytotoxicity observed in in vitro assays. These results highlight 2-substituted 1,3-diazepines as promising candidates for application as organic corrosion inhibitors.