Synthesis, spectral characterization, crystal structure and in vitro DNA/protein binding studies of phosphorous ylide palladacyclic complexes containing azide group.

The reaction between (4-nitrobenzoylmethylene)triphenylphosphorane Pd(II) complex [Pd{κ(2)(C,C)-C₆ H₄PPh₂C(H)CO(C₆ H₄NO₂-4)}(μ-Cl)]₂ and excess of NaN₃ resulted in the μ-N₃ bridged Pd(II) complex [Pd{κ(2)(C,C)-C₆H₄PPh₂C(H)CO(C₆ H₄NO₂-4)}(μ-N₃)]₂ (1), which underwent bridge cleavage reactions with monodentate ligands to afford the monomeric, neutral complexes [Pd{κ(2)(C,C)-C₆ H₄PPh₂C(H)CO(C₆ H₄NO₂-4)}N₃(L)] (L=Me₃Py (1a), PPh₃ (1b)). The complexes were identified and characterized by elemental analyses, infrared (IR), ((1))H, ((13))C{((1))H} and ((31))P{((1))H} NMR spectroscopy. The molecular structure of 1b was determined by single-crystal X-ray diffraction. The interactions of complexes with FS-DNA were investigated using UV absorption and fluorescence spectra. The results suggested that both complexes could interact with FS-DNA through the intercalation mode and follow the binding affinity order of 1a>1b. The reactivity toward protein BSA revealed that the quenching of BSA fluorescence by the two complexes are static quenching, and complex 1a exhibits a higher BSA-binding ability than the complex 1b.