The interaction of phenazinium dye PSF with U.A*U triplex and A.U duplex RNA were investigated using different spectroscopic and hydrodynamic techniques.

The binding affinity of PSF was found to be more in case of the triplex compared to the parent duplex form.

PSF binds through the mode of intercalation with both forms of RNA.

PSF stabilizes the Watson–Crick base paired strand while the Hoogsteen base paired strand remains unaffected.