Conformational Restriction of Cyanine Fluorophores in Far-Red and Near-IR Range
Small molecule fluorescent probes are important tools in diagnostic medicine. Existing far-red and near-IR cyanine fluorophores (e.g. Cy5, Alexa 647, Cy7, ICG) are active in the far-red and near-range, but these agents suffer from modest quantum yields (brightness) which limit wide utility. It has been reported that the limited brightness of these fluorophores is due to an excited-state C-C rotation pathway.