DNA-and BSA-Binding Studies of Dinuclear Palladium(II) Complexes with 1,5-Naphtiridine Bridging Ligands (original) (raw)
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Journal of Organometallic Chemistry, 2017
Novel organometallic palladium(II) complexes [Pd 2 {(C,N)-C 12 H 8 NH 2)} 2 (µ-dppf)Cl 2 ] (2) [Pd 2 {(C,N)-C 12 H 8 NH 2)} 2 (µ-dpp)Cl 2 ] (3) [1,1-bis(diphenylphosphine)-ferrocene (dppf), 1,3-Bis(4-pyridyl)propane (bpp)] have been synthesized, fully characterized by elemental analysis, multi-nuclear (1 H, 31 P{1H}, 13 C{1H}) NMR and IR spectroscopic techniquesand their biological activities such as anti-tumoralactivity and DNA-protein interactions have been investigated. The crystal structure of (2), established by X-ray diffraction, shows that the dppf ligand is bound to the two palladium atoms in bridgedform. The interaction of the complexes with calf thymus DNA (CT-DNA) has been explored by UV-Vis spectroscopy, emission titration and thermal denaturation (T m) methods, which have revealed that these complexes interact with DNA through intercalation mode. Competitive studies with methylene blue (MB) have shown the ability of the complexes to displace the DNAbound MB, suggesting a competition with MB. Furthermore, the microenvironment and the secondary structure of BSA are changed in the presence of the complexes. Competitive binding using Warfarin, Digoxin and site markers, which have definite binding sites, demonstrated that the complexes bind to site I on BSA. Notably, the complexes exhibit significant in vitro selective cytotoxicity against two human cancer cell lines (JURKAT and SKOV3) with IC 50 values varying from 2.3 to 6.7 μM. This indicates that they are more active than cisplatin and showing low cytotoxic activity on normal cells. Finally, molecular modelling studies have been conducted to determine the binding site of the DNA and BSA with the complexes.
Journal of the American Chemical Society, 1981
A new series of trans bis(carbon-palladium) complexes has been prepared. The initial ligands were synthesized from 2,6-bis(chloromethyl)pyridine upon treatment with an appropriate activated methylene compound. When the 2: 1 ligands are treated with potassium tetrachloropalladate(I1) in the presence of pyridine, the corresponding complexes are formed. A single-crystal X-ray structure analysis was conducted on PdC26H,2N208, which revealed that the molecule has exact C2 symmetry, the two heteroaromatic rings are exactly trans and essentially orthogonal, and the palladium coordination is distorted somewhat from ideal square-planar geometry. Refinement in space group Pbcn fitting 1231 observed diffractometer data yielded R = 0.024. Cell constants are a = 9.6261 (12) A, b = 17.7003 (17) A, c = 15.7943 (14) A, and Z = 4. Bond lengths involving Pd are 2.140 (5) 8, for Pd-C, 2.050 (5) 8, for Pd-N(pyridine), and 1.967 (5) 8, for Pd-N to the tridentate ligand. The external pyridine ligand can be readily exchanged with other amines, e.g., y-picoline. From the DNA nicking assay it appears that these trans-palladium complexes do not act on DNA, whereas the related cis-organopalladium reagents are highly active, a relationship analogous to the well-known platinum( 11) series.
Inorganica Chimica Acta, 2021
Complexes [Pd(bipy)(mtzt) 2 ] (1) and [Pd(5,6-dmphen)(mtzt) 2 ] (2) (where Hmtzt, bipy and 5,6-dmphen are 1methyl-1H-1,2,3,4-tetrazole-5-thiol, 2,2′-bipyridine and 5,6-dimethyl-1,10-phenanthroline, respectively) were synthesized by the reaction of a mixture of Hmtzt and 2,2′-bipyridine (1) or 5,6-dimethyl-1,10-phenanthroline (2) with Pd(II) chloride. Complexes 1 and 2 were fully characterized by elemental analysis, 1 H NMR, IR, UV-Vis, luminescence spectroscopy as well as single-crystal X-ray diffraction method. According to single-crystal X-ray diffraction, central Pd(II) ions in 1 and 2 have a slightly distorted square-planar geometry, involving the S atoms from two mptrz − ligands and two nitrogen atoms from bipy (complex 1) and 5,6-dmphen (complex 2) ligands (τ 4 = 0.09 for 1 and 0.07 for 2). Additionally, some well-known non-covalent intermolecular interactions such as hydrogen bonding (complexes 1 and 2), π-π (complexes 1 and 2), and ring-metal interactions (complex 2) have also been involved in these complexes. These kinds of interactions have been observed to be responsible for the formation of the 3D supramolecular structure. The luminescence properties of the free ligand, as well as the complexes 1 and 2, were investigated in solution. The interaction of the complexes with DNA was investigated by UV-Vis absorption spectra. The results indicate that complexes bind to DNA and the intrinsic binding constant (K b) of complexes 1 and 2 were about 2.19 × 10 5 and 1.51 × 10 5 M −1 , respectively. Gel electrophoresis assay demonstrates the ability of the complexes to bind the plasmid DNA. The anti-tumor properties of Pd(II) complexes were evaluated as in vitro anti-proliferative activity by MTT assay in human breast cancer cell lines (MCF-7, SKBR-3, and MDA-MB-231). It suggests that complex 2 might dedicate important anti-tumor properties and 5,6-dmphen ligand has an important effect on cytotoxicity, so complex 2 shows IC 50 value in μM range as effective as cisplatin.
Polyhedron, 2019
Novel palladium(II) and platinum(II) complexes (trans-[PdCl2L2] and trans-[PtCl2L2] {L = 2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-(sec-butyl)-2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-cyclopropyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide, N-cyclohexyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide, 2-(2-(tert-butyl)-2H-tetrazol-5-yl)acetamide and 2-(2-(tert-butyl)-2H-tetrazol-5-yl)-N-cyclohexylacetamide} 1b–6b and 1c–4c) were synthesized and characterized by elemental analyses (CHN), HRESI+-MS, 1H, 13C{1H}, 195Pt NMR and IR spectroscopies, DSC/TG analysis, as well as by X-ray single crystal diffraction {for (2-(5-methyl-1H-tetrazol-1-yl)acetamide) 1a·H2O, trans-[PdCl2(2-(5-methyl-1H-tetrazol-1-yl)acetamide)2] 1b, trans-[PdCl2(N-cyclopropyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide)2] 3b and trans-[PdCl2(N-cyclohexyl-2-(5-methyl-1H-tetrazol-1-yl)acetamide)2] 4b}. The binding of complexes 2b and 5b to calf-thymus DNA (CT DNA) and BSA (bovine serum albumin) was studied by means of CD, UV and fluoro...
Journal of Biological Inorganic Chemistry, 2022
The pincer complexes, [Pd(L 1)Cl]BF 4 (PdL 1), [Pd(L 2)Cl]BF 4 (PdL 2), [Pd(L 3)Cl]BF 4 (PdL 3), [Pd(L 4)Cl]BF 4 (PdL 4) were prepared by reacting the corresponding ligands, 2,6-bis[(1H-pyrazol-1-yl)methyl]pyridine (L 1), bis[2-(1H-pyrazol-1-yl)ethyl] amine (L 2), bis[2-(1H-pyrazol-1-yl)ethyl]ether (L 3), and bis[2-(1H-prazol-1-yl)ethyl]sulphide (L 4) with [PdCl 2 (NCMe)] 2 in the presence NaBF 4. The solid-state structures of complexes PdL 1-PdL 4 confirmed a tridentate coordination mode, with one chloro ligand completing the coordination sphere to afford square-planar complexes. Chemical behaviour of the complexes in solution confirms their stability in both aqueous and DMSO stock media. The electrochemical properties of the compounds showed irreversible two-electron reduction process. Kinetic reactivity of Pd complexes with the biological nucleophiles viz, thiourea (Tu), L-methionine (L-Met) and guanosine 5′-diphosphate disodium salt (5'-GMP) followed the order: PdL 2 < PdL 3 < PdL 4 , and PdL 2 < PdL 1. The kinetic reactivity is subject to the electronic effects of the spectator ligand(s), and the trend was supported by the DFT computed results. The palladium complexes PdL 1-PdL 4 bind to calf thymus (CT-DNA) via intercalation mode. In addition, the bovine serum albumin (BSA) showed good binding affinity to the complexes. The mode of quenching mechanism of the intrinsic fluorescence of CT-DNA and BSA by the complexes was found to be static. The order of interactions of the complexes with DNA and BSA was in tandem with the rate of substitution kinetics. The complexes, however, displayed relatively low cytotoxicity (IC 50 > 100 µM) when tested against the human cervical adenocarcinoma (HeLa) cell line and the transformed human lung fibroblast cell line (MRC-5 SV2).
Molecules
Three new palladium complexes ([Pd(DABA)Cl2], [Pd(CPDA)Cl2], and [Pd(HZPY)Cl2]) bearing dinitrogen ligands (DABA: 3,4-diaminobenzoic acid; CPDA: 4-chloro–o-phenylenediamine; HZPY: 2-hydraziniopyridine) were synthesized, characterized, and tested against breast cancer (MCF-7), prostate carcinoma cell line (PC3) and liver carcinoma cell line (HEPG2). [Pd(DABA)Cl2] complex exhibited the highest inhibition percentage, lying between 68–71%. The hydrolysis mechanism of each palladium complex, the key step preceding the binding to the biological target, as well as their photophysical properties were explored by means of DFT and TDDFT computations. Results indicate a faster hydrolysis process for the Pd(DABA)Cl2 complex. The computed activation energies for the first and second hydrolysis processes suggest that all the compounds could reach DNA in their monohydrated form.
Transition Metal Chemistry, 2011
A series of distorted square planar palladium(II) complexes with dithiocarbamic acids of general formula [Pd(L) 2 ], where L = 4-methylpiperazine-l-carbodithioic acid anion, morpholine-4-carbodithioic acid anion or 4-benzylpiperidine-l-carbodithioic acid anion for complexes 1a, 1b and 1c, respectively, have been synthesized. The complexes were characterized by physicochemical and spectroscopic methods; in addition, the structure of complex 1a was characterized by single crystal X-ray crystallography. The interaction of these palladium complexes with CT-DNA was investigated with the help of absorption and emission spectroscopy. The association constant K b was deduced from the absorption spectra, while the number of binding sites and the binding constant were calculated from the fluorescence quenching data. The results suggest an intercalative interaction of the complexes with CT-DNA.