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.

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>

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

Effect of resin and photoinitiator on color, translucency and color stability of conventional and low-shrinkage model composites

OBJECTIVE: To study the effect of a low-shrinkage methacrylate monomer and monoacylphosphine oxide photoinitiator on color, translucency, and color stability of model resin-based composites (RBCs). METHODS: Four micro-hybrid RBCs were prepared containing barium-glass fillers in bisphenol A-glycidyl-methacrylate (BisGMA) and triethyleneglycol-dimethacrylate (TEGDMA) or urethane-based low-shrinkage monomer FIT-852 (FIT; Esstech Inc.) and TEGDMA matrix. Camphorquinone (CQ)/amine or Lucirin TPO were used as photoinitiators. Commercial low-shrinkage RBCs (Charisma Diamond, Heraeus Kulzer and N'Durance, Septodont) and conventional RBCs (Tetric EvoCeram, Ivoclar Vivadent and Filtek Z250, 3M ESPE) were used as controls. Color and translucency were measured using Thermo Scientific Evolution (Thermo Fisher Scientific) and SpectroShade™ Micro (MHT Optic Research) spectrophotometers. Color stability was evaluated after immersion in black tea (pure, with milk or lemon) and distilled water. Data were analyzed using analyses of variance with Tukey's post-test (α=0.05). RESULTS: Photoinitiators had no significant effect on baseline color. Initially whiter FIT-based RBCs showed greater staining in all staining solutions than BisGMA-based RBCs. TPO-containing RBCs showed better color stability than CQ-containing RBCs irrespective of the base monomer. Tea and tea with lemon induced greatest color changes. Adding milk to tea significantly reduced material staining. SIGNIFICANCE: Urethane-based low-shrinkage monomer FIT and conventional BisGMA affected color, translucency and color stability of their respective RBCs. Despite being used in posterior teeth, low-shrinkage RBCs are expected to have favorable optical and esthetic properties. Manufacturers are urged to provide information on optical properties of monomers and monomer mixtures in their low-shrinkage RBCs to allow understanding of interaction with fillers and photoinitiators.publisher: Elsevier articletitle: Effect of resin and photoinitiator on color, translucency and color stability of conventional and low-shrinkage model composites journaltitle: Dental Materials articlelink: http://dx.doi.org/10.1016/j.dental.2015.11.027 content_type: article copyright: Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.status: publishe