Rhodamine B and fluorescein were chemically modified with ketones and aldehydes to control the steric environment and electron density surrounding the binding site in an attempt to impart selectivity for specific metals.  Solution phase studies evaluated dye binding to iron (III), which is formed in the corrosion process, relative to other metal ions such as iron (II), aluminum (III), chromium (III), and zinc (II).  Evaluation using ultraviolet-visible spectroscopy and fluorescence measurements revealed significant environment effects as the solvation solvent was changed.  These dyes were then integrated into epoxy coating formulations to determine the ability of these dyes to detect and report the early onset of metal corrosion, and to ascertain the impact of the solid state on dye-metal binding interactions.  The detection limit was evaluated by determining the effectiveness of the fluorescence in response to variations in coating thicknesses.

Synthesis and application of rhodamine B and fluorescein dyes for early corrosion sensing

243rd National Meeting (2012)

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