Highly photostable dyes
Fluorescent dyes that can withstand irradiation over long time-scales are rare. In focused laser light, the short list of dyes is further reduced. The long lifetime triangulenium probes are highly photostable, but can easily undergo multiphoton processes under intense irradiation, which leads to decomposition of the dye. Therefore a new class of dyes are needed for these applications: Highly photostable dyes: KU-P and KU-T.
KU-P and KU-T are not water soluble and of limited use in bioimaging. But if you want to do single molecule microscopy, they are ideal model systems.