Tyrian purple Tyrian purple Tyrian purple (, "porphúra"; ), also known as Tyrian red, Phoenician purple, royal purple, imperial purple or imperial dye, is a reddish-purple natural dye. It is a secretion produced by several species of predatory sea snails in the family Muricidae, rock snails originally known by the name "Murex". In ancient times, extracting this dye involved tens of thousands of snails and substantial labor, and as a result, the dye was highly valued. The main chemical is 6,6′-dibromoindigo. Tyrian purple may first have been used by the ancient Phoenicians as early as 1570 BC. The dye was greatly prized
Squaraine dye Squaraine dye Squaraine dyes are a class of organic dyes showing intense fluorescence, typically in the red and near infrared region (absorption maxima are found between 630 and 670 nm and their emission maxima are between 650–700 nm). They are characterized by their unique aromatic four membered ring system derived from squaric acid. Most squaraines are encumbered by nucleophilic attack of the central four membered ring, which is highly electron deficient. This encumbrance can be attenuated by the formation of a rotaxane around the dye to protect it from nucleophiles. They are currently used as sensors for ions and have