1-[2-(Maleimido)ethyl]-4-[2-(3,4-dihydro-2H-1-benzopyran-6-yl)-5-oxazolyl]pyridinium triflate is a new class of highly photostable, water soluble fluorescent labels with large Stoke's shift, high QY in aqueous media and pH tolerance. Major disadvantage: rel. low extinction coefficient (E slightly >20'000 in EtOH) (1).
