Cy7 is a far-red (near-infrared) emitting dye with a peak excitation at 756 nm and maximum emission at 776 nm in PBS. Cy7 is spectrally almost identical to other near-IR dyes, including DyLight 750™, IRDye™ 750 dye and Alexa Fluor™ 750, and is ideal for multi-color applications. The fluorescent quantum yield and stability of Cy7 dye are remarkably improved by partially rigidizing two of the methine groups into a ring system.