Synthesis, spectral, X-ray crystallography, electrochemistry, DNA/protein binding and radical scavenging activity of new palladium(II) complexes containing triphenylarsine

The reactions of [PdCl2(AsPh3)2] with equimolar amount of salicylaldehyde-4(N)-phenylthiosemicarbazone [H2-(Sal-ptsc)] (H2L1) and 2-hydroxy-1-naphthaldehyde-4(N)-methylthiosemicarbazone [H2-(Nap-mtsc)] (H2L2) were carried out in ethanol/dichloromethane medium. The obtained products (1 and 2) were characterized by variours spectral and analytical techniques. From the X-ray crystallographic studies, it is inferred that both the ligands coordinate as ONS tridentate dibasic donor by forming more common five and six member chelate rings. The complex 1 crystallizes in the triclinic space group P 1 ¯ with two molecules per unit cell, has the dimensions of a = 10.1680(12) Å, b = 10.5535(12) Å, c = 13.3852(15) Å, α = 78.9980(10)°, β = 82.7610(10)° and γ = 86.2490(10)°. The complex 2 crystallizes in the monoclinic space group P2(1)/n with four molecules per unit cell, has the dimensions of a = 14.0981(3) Å, b = 11.2881(2) Å, c = 18.2678(3) Å, α = 90°, β = 111.00(10)° and γ = 90°. The complexes 1 and 2 have been tested for their binding towards Herring Sperm (HS)-DNA and BSA (bovine serum albumin). The new complexes bound to DNA by electrostatic binding mode and they had a strong binding affinity with BSA. The mechanism of quenching was found as static. In addition, the free radical bleaching ability of complexes with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical was carried out.