Heterocyclic biomolecules as green corrosion inhibitors

Bioinspired heterocyclic organic molecules have high significance as potential substitutes to the existing inhibitor chemistries, which are considered toxic and costly. Here, we provided a detailed review of the different kinds of heterocyclic macrocyclic compounds and biomolecules and their various chemically modified derivatives and composites as corrosion inhibitors. An account of typically used five, and six-membered heterocyclic compounds (basic constituents of biomolecules, drugs, etc.) is also provided. The review starts with a background of the different corrosion issues commonly encountered in the industries and the existing inhibitor solutions. Concise descriptions of various heterocyclic compounds, their molecular structural aspects, and Green Chemistry principles are presented. The bio-inspired heterocyclic organic corrosion inhibitors are discussed under macrocyclic compounds, pharmaceutical products, amino acids, ionic liquids, natural product extracts, carbohydrates, and biopolymers. Their green synthesis strategies, advantages, challenges, and cost concerns were deliberated. The review presented herein would be helpful as a reference for both academic and industrial researchers.