Experimental and theoretical study of tetraphenylethylene-based dicationic compounds for corrosion inhibition of steel and brass in an acidic medium

Luminogens with aggregation-induced emission (AIE) properties offer the possibility to realize surface fluorescence for visual detection as well as precise dosing of corrosion inhibitors. Herein, a series of tetraphenylethylene-based dicationic AIE compounds were developed to study their corrosion inhibition behavior toward steel and brass in 0.5 M H2SO4. TPE-2NH(3)center dot 2SCN was proved to be an effective corrosion inhibitor for both metals, with inhibition efficiencies of over 97% for steel and over 99% for brass. Intensive AIE fluorescence was observed after its adsorption on brass, while the other five compounds bearing identical cations but diverse anions exerted a limited protective effect on both metals. The distinctive inhibitory behaviors of these compounds were attributed to hard and soft acids and bases theory and electrostatic attraction. Theoretical calculations were further applied to investigate the inhibition mechanism.