Synthetic, Crystallographic, and Computational Study of Copper(II) Complexes of Ethylenediaminetetracarboxylate Ligands

Copper(II) complexes of hexadentate ethylenediaminetetracarboxylic acid type ligands H4eda3p and H4eddadp (H4eda3p = ethylenediamine-N-acetic-N,N′,N′-tri-3-propionic acid; H4eddadp = ethylenediamine-N,N′-diacetic-N,N′-di-3-propionic acid) have been prepared. An octahedral trans(O6) geometry (two propionate ligands coordinated in axial positions) has been established crystallographically for the Ba[Cu(eda3p)]·8H2O compound, while Ba[Cu(eddadp)]·8H2O is proposed to adopt a trans(O5) geometry (two axial acetates) on the basis of density functional theory calculations and comparisons of IR and UV−vis spectral data. Experimental and computed structural data correlating similar copper(II) chelate complexes have been used to better understand the isomerism and departure from regular octahedral geometry within the series. The in-plane O−Cu−N chelate angles show the smallest deviation from the ideal octahedral value of 90°, and hence the lowest strain, for the eddadp complex with two equatorial β-propionate rings. A linear dependence between tetragonality and the number of five-membered rings has been established. A natural bonding orbital analysis of the series of complexes is also presented.

Chelating properties of EDTA-type ligands containing six-membered backbone ring toward copper ion:Structure, EPR and TD-DFT evaluation

The P-APC ligands (EDTA-like aminopolycarboxylate ligands comprising 1,3-propanediamine backbone) H(4)pdta, H(4)pd(3)ap, H(4)pddadp and H(4)pdtp (H(4)pdta = 1,3-propanediamine-N,N,N',N'-tetraacetatic acid; H(4)pd(3)ap = 1,3-propanediamine-N,N,N'-triacetic-N'-3-propionic acid; H4pddadp = 1,3-propanediamine-N,N'-diacetatic-N,N'-di-3-propionic acid; H(4)pdtp = 1,3-propanediaminetetra-3-propionic acid) were investigated. The chelating ligands coordinate to copper(II) via five or six donor atoms affording distorted trigonal-bipyramid and octahedral structures that were verified by X-ray analysis for Ba[Cu(pd(3)ap)]center dot 6H(2)O (1) and trans(O-6)-Ba[Cu(pddadp)]center dot 8H(2)O (2) complexes respectively. The impact of counter-ions on the P-APC complexes is shown in detail together with the analysis of another strain parameters. EPR spectral results confirm the penta-coordination of 1 and hexa-coordination of 2 in aqueous solution, even if several Cu(II) species with different protonation degree exist as a function of pH, and indicate that a hexa-coordinated structure is favored when the two axial COO- donors close five-membered chelate rings. We also present here the results of molecular mechanics (LFMM) calculations based on our previously-developed force field along with results of DFT (Density Functional Theory). On the basis of extensive DFT and TD-DFT calculations the B1LYP/6-311++G(d,p) level has been seen as an accurate theory for calculating and predicting the UVVis spectra in case of copperP-APC compounds. (C) 2016 Elsevier Ltd. All rights reserved

Crystal structure, configurational and DFT-NEDA analysis of nickel(II) complexes with pentadentate ed3a-type ligands

<p>The O-O-N-N-O-type pentadentate ligands H(3)ed3a, H(3)1,2-pd3a, H(3)eda2p and H(3)ed3p (H(3)ed3a stands for ethylenediamine-N,N,N'-triacetic acid; H(3)1,2-pd3a stands for 1,2-propanediamine-N,N,N'-triacetic acid; H(3)eda2p stands for ethylenediamine-N-acetato-N,N'-di-3-propionic acid and H(3)ed3p stands for ethylenediamine-N,N,N'-tri-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. H(3)ed3a, H(3)1,2-pd3a, H(3)eda2p and H(3)ed3p ligands coordinate to nickel(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in case of all investigated Ni(II) complexes. A sixth place within octahedra has been occupied by the molecule of water. A six coordinate, octahedral geometry has been established crystallographicaly for the [Ni(H2O)(6)][Ni(ed3a)(H2O)](2)center dot 2H(2)O complex. Structural data correlating similar chelate Ni(II) complexes have been used to carry out an extensive configuration analysis. This is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data. Natural Energetic Decomposition Analysis (NEDA) has been done for the LNi center dot center dot center dot OH2 unit. (C) 2012 Elsevier Ltd. All rights reserved.</p>

Nickel(II) in chelate N2O2 environment. DFT approach and in-depth molecular orbital and configurational analysis

<p>The O-N-N-O-type tetradentate ligands H2S,S-eddp (H2S,S-eddp stands for S,S-ethylenediamine-N,N'-di-2-propionic acid) and H(2)edap (H(2)edap stands for ethylenediamine-N-acetic-N'-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. N2O2 ligands coordinate to the nickel(II) ion via four donor atoms (two deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in the case of all investigated Ni(II) complexes. A six coordinate, octahedral geometry has been verified crystallographically for the s-cis-[Ni(S,S-eddp)(H2O)(2)] complex. Structural data correlating similarly chelated Ni(II) complexes have been used to carry out an extensive configuration analysis. Molecular mechanics and Density Functional Theory (DFT) have been used to model the most stable geometric isomer, yielding, at the same time, significant structural and spectroscopic (TDDFT) data. The results from density functional studies have been compared to X-ray data. Natural Bond Orbital (NBO) and Natural Energetic Decomposition Analysis (NEDA) have been done for the [Ni(edda-type)(H2O)(2-n)] and nH(2)O fragments. Molecular orbital analysis (MPA) is given as well. The infra-red and electronic absorption spectra of the complexes are discussed in comparison to the related complexes of known geometries.</p>

Antitumor effects of a tetradentate amido-carboxylate ligands and corresponding square-planar palladium(II) complexes toward some cancer cells. Crystal structure, DFT modeling and ligand to DNA probe Docking simulation

<p>Novel square-planar palladium(II) complexes with O-N-N-O-type ligands H(4)mda (H(4)mda = malamido-N,N'-diacetic acid) and H(4)obp (H(4)obp = oxamido-N,N'-di-3-propionic acid) were prepared and characterized. The ligands coordinate to the palladium(II) ion via two pairs of deprotonated ligating atoms with square chelation. A four coordinate, square-planar geometry was verified crystallographicaly for the K-2 [Pd(mda)]center dot H2O complex. The binary and ternary systems of Pd(II) ion with H(4)mda or H(4)obp (L) as primary ligands and guanosine (A) as secondary ligand were studied in aqueous solutions in 0.1 M NaCl ionic medium at 25 degrees C by potentiometric titrations. In addition, calculations based on density functional methods (DFT) were carried out. A natural bonding orbital analysis indicated that the Pd-N bonds are three-centric in nature and mainly governed by charge transfer via a strong delocalization of the oxygen lone pair with "p" character into the bonding Pd-N orbital. Mononuclear palladium(II) complexes together with amido acid N,O-containing ligands were tested against several tumor cells and reveal significant antitumor activity and lower resistance of tumor cells in vitro than cisplatin. In this paper, interactions of palladium complexes with DNA are discussed in order to provide guidance and determine structure and antitumor activity relationships for continuing studies of these systems. Docking simulation on DNA dodecamer or 29-mer (Lippard solved crystal structures), suggests several favorable interactions with the hydrogen pocket/binding site for the incoming ligands. These results support amidoacids/Pd complexes as novel antitumor drugs and suggest that their potent cell life inhibition may contribute to its anti-cancer efficacy. (c) 2013 Elsevier Inc. All rights reserved.</p>

Preparation, configurational and DFT-NBO analysis of nickel(II) complexes with edta-type ligands containing six-membered backbone ring:crystal structure of [Ni(H2O)(6)][Ni(1,3-pdta)]center dot 2H(2)O

New hexadentate nickel(II) complex Mg[Ni(1,3-pd3ap)]center dot 10H(2)O containing unsymmetrical edta-type ligand, 1,3-propanediamine-N,N,N '-triacetate-N-3-propionate (1,3-pd3ap), has been prepared, chromatographically separated, and characterized. Only one [trans(O-5)] of the two possible geometrical isomers was isolated. In this isomer, the two five-membered glycinate rings (R rings) occupy trans-axial sites while the one glycinate ring and one beta-alaninate ring lie in the equatorial plane with the two diamine nitrogens (G rings). This result confirms the assignment made on the basis of the density functional theory (DFT), IR, and UVVis spectral data analysis. In order to see cation influence on the structural and electronic behavior, [Ni(H2O)(6)][Ni(1,3-pdta)]center dot 2H(2)O complex has also been prepared and its structure verified by an X-ray analysis. Spectral data and electronic transition assignment, DFTnatural bonding orbital, and an extensive strain analysis are discussed in comparison with those of other [Ni(edta-type)](2-) complexes of known configuration

Copper(II) complexes with unsymmetrical pentadentate ed3a-type diamino-tricarboxylate ligands. Crystal structures, configurational analysis and DFT study of complexes

The O-O-N-N-O-type pentadentate ligands H(3)ed3a, H(3)pd3a and H(3)pd3p (H(3)ed3a stands ethylenediamine-N,N,N'-triacetic acid; H3pd3a stands 1,3-propanediamine-N,N,N'-triacetic acid and H3pd3p stands 1,3-propanediamine-N,N,N'-tri-3-propionic acid) and the corresponding novel octahedral or square-planar/trigonal-bipyramidal copper(II) complexes have been prepared and characterized. H(3)ed3a, H(3)pd3a and H(3)pd3p ligands coordinate to copper(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral in case of ed3a(3-) and intermediate square-pyramidal/trigonal-bipyramidal structure in case of pd3a(3-) and pd3p(3-). A six coordinate, octahedral geometry has been established crystallographically for the [Mg(H2O)(6)][Cu(ed3a) (H2O)](2) center dot 2H(2)O complex and five coordinate square-pyramidal for the [Mg(H2O)(5)Cu(pd3a)][Cu(pd3a)] center dot 2H(2)O. Structural data correlating similar chelate Cu(II) complexes have been used for the better understanding the pathway: octahedral -> square-pyramidal trigonal- bipyramid geometry. An extensive configuration analysis is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) programs have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data. (c) 2006 Elsevier B.V. All rights reserved

Rhodium(III) in a cage of the 1,3-propanediamine-N,N,N′-triacetate chelate: X-ray structure, solution equilibria, computational study and biological behavior

Two new octahedral Rh(III) complexes that are potential chemotherapeutic agents have been synthesized from the 1,3-propanediamine-N,N,N’-triacetate ligand (1,3-pd3a): [Rh(1,3-pd3a)(H2O)]·2H2O (1) and Na[Rh(1,3-pd3a)Cl]·2H2O (2). Both complexes were characterized by IR, UV–Vis and NMR spectroscopy, as well as elemental analysis. Only the structure of 2 was determined by a single crystal X-ray diffraction study. The asymmetric unit contains the negatively charged rhodium complex, a sodium ion and two water molecules. The positions of the carboxylate groups define the cis-polar geometry. DFT calculations on 1 and 2 have also been done to confirm experimental results. In order to determine the protonation constants of 1,3-H3pd3a, stability constants and the stoichiometry of the complexes in aqueous solution, pH-potentiometry and UV–Vis spectrophotometry were used. Docking of 1 to human serum albumin (HSA) gives the reasonable assumption that this complex can be easily transported to the target cells. The complexes, as well as the 1,3-pd3a and ed3a ligands, were tested against various cancer and one normal human cell lines. Complex 2 and both ligands display significant cytotoxicity against the HeLa cancer cell line, while 1 shows good antitumor activity against MCF-7. Flow cytometry analysis showed the apoptotic death of the cells with cell cycle arrest in the G2/M phase (Na[Rh(1,3-pd3a)Cl]·2H2O) and G0/G1 phase (1,3-pd3a)