Beyond the color: A structural insight to eosin-based lakes

On production and investigations of different eosin lake substrates, two main anchored species have been distinguished: H-bonded for eosin onto Pb-substrates and a further bridged bidentate for eosin onto alumina. A prominent tendency to form 2:1 eosin:Pb adducts emerged in each Pb-containing recipe. Evidence concerning historical lakes suggests that eosin can diversely coordinate to metals thus producing a variety of nuances in according to experimental pH and reaction conditions. This behavior may well explain observed discrepancies between historical recipes and experimental findings regarding the coordination of eosin to one or more metals.