BDP R6G maleimide, a borodipyrromethane fluorophore, exhibits absorption and emission wavelengths akin to R6G rhodamine. It is a thiol-reactive dye and interacts with thiol groups to create thioester bonds [1]. This compound is commonly used for sulfhydryl labeling of cysteine residues, offering more site-specific labeling than the NHS ester of the amine group.