Ancient Pigment Resurrected For Modern Applications

Egyptian blue, a synthetic pigment first produced by the ancient Egyptians around 2500 B.C., could find use in the modern era in applications such as biomedical analysis, telecommunications, and lasers, according to a new report (Chem. Commun., DOI: 10.1039/b902563d). A team led by Gianluca Accorsi of Italy's Institute for Organic Synthesis & Photoreactivity performed a quantitative study of the colorant's luminescence properties to assess its quantum efficiency and lifetime. They found that the CaCuSi₄O₁₀ pigment, also known as cuprorivaite, has an exceptionally high luminescence quantum yield for a molecular-level infrared emitter—10.5%. Egyptian blue's long luminescence lifetime and intense IR emission make it a promising candidate for use in biomedical applications, for example, because IR photons can deeply penetrate human tissue and the pigment's emission at 910 nm minimizes light absorption by tissues. Furthermore, the pigment is extremely stable, exhibiting bright luminescence even after millennia in both dry and damp environments. "Ancient Egyptians may not have attained eternal life," the researchers muse, "but one of their most frequently used pigments may now have a future in a variety of high-tech applications."