The newly synthesized Keio Fluros, which are based on boron-dipyrromethene (BDP), have excellent and useful optical properties: vivid colors and sharp emission in the visible-near-infrared region (583-738 nm), high quantum yields (Phi: 0.56-0.98), high extinction coefficients (185000-288000 M-1 cm(-1)), and good photostabilities. These optical properties are superior to many of the existing fluorescent dyes such as rhodamines, cyanines, or other BDP-based fluorescent dyes.