9-(2,2-Dicyanovinyl)julolidine (DCVJ) is a fluorogenic dye that is considered a fluorescent molecular rotor because its properties depend on the rotational relaxation of the molecule, which can be influenced by the viscosity of the solvent used. It has an excitation maximum at approximately 450 nm, and its emission is approximately 480 or 505 nm for low or high viscosity solvents, respectively. DCVJ has been used to study tubulin dynamics because its fluorescence increases when bound to tubulin sheets but is lower when bound to microtubules.