Rhodamines NN: A Novel Class of Caged Fluorescent Dyes

A bright future: The reaction of diazomethane with acid chlorides obtained from N,N,N′,N′-tetraalkylrhodamines affords 2-diazo-2,3-dihydro-1H-indenespiro[1,9′]-9H-xanthen-3-ones—a novel class of caged rhodamines. These dyes allow new imaging procedures based on the step-wise activation and detection of several fluorescent markers (see picture).