Compounds that are selective binding agents specific for RNA secondary and tertiary structures and a fluorescence assay for detecting the binding of small molecules to T-box antiterminator model mRNAs. The compounds include novel tri-substituted oxazolidinones and amino alcohols. The assay provides fluorescently labeled model mRNAs that include conserved sequence information typical of antiterminator bulge regions found in the mRNA of T-box gene regulatory systems.