LAUSR

Abstract New bisphosphoramides (having phenyl (EDAPOPh 2 ) and ethoxy (EDADEP) substituents attached to phosphoryl groups bridged with ethylenediamine spacer) are synthesized and structurally characterized by spectroscopic techniques as well as elemental analysis. The molecular structure of EDAPOPh 2 was determined by single crystal X-ray diffraction technique. The interaction of these bisphosphoramides with calf thymus DNA ( ct -DNA) is investigated using UV–Visible absorption and fluorescence spectral data as well as the DFT calculations. These studies reveal that EDAPOPh 2 and EDADEP interact with DNA in a partial intercalation mode. The intrinsic binding constants K b of two different bisphosphoramides with ct -DNA were determined by fluorescence spectroscopy as 2.08 × 10 4 and 3.86 × 10 4  M −1 respectively. The results indicated that the two compounds bind to ct -DNA with different binding affinities, i.e. EDAPOPh 2  > EDADEP. The binding mechanism of these bisphosphoramides to ct -DNA is also discussed.