This invention relates to new fluorescent chemical entities, especiallyfluorescent molecules that comprise biocompatible N, N-disubstitutedsulfonamide fluorochromes. This invention also relates to the correspondingreactive versions of such molecules. This invention also relates to thecorresponding conjugates with moieties such as peptides, proteins, variousbiomolecules, carbocyclic and heterocyclic compounds, sugars, and their usesthereof.