Novel fluorescent reactive dyes as intermediates for the preparation of UV and Vis wavelength fluorescent probes

To prepare reactive dyes matching the optical properties of 2-(1,1-dicyano-propenyl-2)-6-dimethylaminonaphthalene (DDNP), 2-ethylaminoethanol or 4-piperidinemethanol were used in a Bucherer reaction with 1-(6-hydroxy-2-naphthyl)-1-ethanone. The two amines were chosen to mimic the dimethylamino group's steric and electronic (inductive) effects and to provide a reactive site for ligand attachment. The intermediate hydroxy derivatives were transformed into fluorescent reactive p-toluenesulfonic acid esters which in turn were conjugated to the test ligand spiperone. Knoevenagel condensation with malononitrile afforded Vis wavelength fluorescent probes.