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

Abstract

The reaction between (4-nitrobenzoylmethylene)triphenylphosphorane Pd(II) complex [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}(μ-Cl)]2 and excess of NaN3 resulted in the μ-N3 bridged Pd(II) complex [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}(μ-N3)]2 (1), which underwent bridge cleavage reactions with monodentate ligands to afford the monomeric, neutral complexes [Pd{κ2(C,C)–C6H4PPh2C(H)CO(C6H4NO2-4)}N3(L)] (L=Me3Py (1a), PPh3 (1b)). The complexes were identified and characterized by elemental analyses, infrared (IR), 1H, 13C{1H} and 31P{1H} 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.