Athanassios N. Papadopoulos

Bio: Athanassios N. Papadopoulos is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Crystal structure & Schiff base. The author has an hindex of 4, co-authored 4 publications receiving 216 citations.

First Example of a CuII Polymeric Complex Having a Tetranuclear Repeating Unit with a S = 2 Ground State. Crystal Structure of [Cu4(dpk·CH3O)2Cl6]n (dpk·CH3OH = Unimethylated Diol of Di-2-pyridyl Ketone)

Abstract: The synthesis, crystal structure and properties of the compound [Cu4(dpk·CH3O)2Cl6]n (dpk·CH3OH = unimethylated diol of di-2-pyridyl ketone) (1), the first example of a copper(II) polymer having a tetrameric repeating unit with S = 2 ground state is reported. The synthesis of compound 1 has been achieved via the reaction of CuCl2 with dpk in methanol. The base-catalyzed addition results in the formation of a unimethylated diol which may deprotonated. Crystal structure data: [C12H11N2O2Cl3Cu2], Mr = 448.68; triclinic; space group P1; a = 7.800(1) (A); b = 8.946(1) (A); c = 13.383(1) (A); α = 118.964(3)°; β = 92.693(3)°; γ = 66.824(3)°; Z = 2. Variable temperature magnetic susceptibility measurements indicate the presence of a ferromagnetic behavior with antiferromagnetic coupling below 15 K. The best fit parameters obtained from this model are J1 = 71.32 cm-1, J2 = 1.43 cm-1, J3 = 0.07 cm-1, J4 = 0 (fixed), zJ = −0.553 cm-1, and g = 2.1 (fixed). The energy levels obtained from the fitting procedure show ...

Synthesis, characterisation and crystal structure of molybdenum and molybdenum–copper hydroxy-rich Schiff-base complexes

Abstract: The reaction of hydroxy-rich Schiff bases [H3L = XC6H3(OH)CHNC(R)(CH2OH)2 where X = H, 5-Cl or 5-Br and R = Me or Et] with [MoO2(acac)2](acac = acetylacetonate) gave mononuclear complexes [MoO2(HL)(MeOH)]. The complexes were characterised by spectroscopic methods and by a single-crystal structure determination. Reaction of the mononuclear complexes with Ph2PCH2PPh2 in methanol or acetonitrile led to five-co-ordinate polymeric compounds of the type [MoO(L)]n in which the fifth position of the distorted square pyramid is occupied by the oxygen atom of a CH2O– moiety of a neighbouring repeat unit. The complex [MoO2(HL3)(MeOH)][H3L3= 2-(5-chlorosalicylideneamino)-1,3-dihydroxy-2-methylpropane] reacted with Cu(O2CMe)2 in methanol–acetonitrile to yield the mixed-metal cluster [Cu2Mo2O4L32(OMe)2] with a Cu2Mo2O4 cubane-like core. Reflux of this complex with an excess of 2,2′-bipyridine in acetonitrile yielded pale blue-green crystals of the tetranuclear cluster [CuMo3O8(HL3)2(bipy)2] the structure of which has been determined by X-ray crystallography. The molybdenum part may be described in terms of three oxo-bridged centres, one tetraoxomolybdate [MoO4]2– and two six-co-ordinated MoO2(Schiff base) moieties. The magnetic properties of this compound have been studied in the temperature range 5–300 K.

Hydroxamic Acids − An Intriguing Family of Enzyme Inhibitors and Biomedical Ligands

Abstract: This review on hydroxamic acids deals with their efficacy as inhibitors of enzymes including cyclooxygenases, their synthesis, the complexity and structural diversity of their metal complexes, and their ability to act as effective nitric oxide donors. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Adventures in the Coordination Chemistry of Di-2-pyridyl Ketone and Related Ligands: From High-Spin Molecules and Single-Molecule Magnets to Coordination Polymers, and from Structural Aesthetics to an Exciting New Reactivity Chemistry of Coordinated Ligands†‡

Abstract: The coordination chemistry of di-2-pyridyl ketone and related ligands is reviewed. An outline of the variety of such ligands is presented. References are given to methods for the synthesis of ligands that are not available on the market. The activation of the carbonyl group(s) of some of the ligands towards further reactions seems to be an emergent area of synthetic inorganic chemistry. The coordination chemistry of each ligand with metals is briefly described. Emphasis is placed on structural features and physical properties (mainly magnetic) of the resulting metal clusters and coordination polymers. The structural diversity of the complexes stems from the ability of the deprotonated diol- or hemiketal-type ligands to adopt a variety of bridging coordination modes depending on the number of carbonyl groups, the nature of the extra donor groups in the molecule and on the reaction conditions. Employment of a second organic or inorganic ligand in this chemistry gives an extraordinary structural flexibility in the resulting mixed-ligand systems. The initial use of 1,1′-carbonyldiimidazole and 1,1′-oxalyldiimidazole in copper(II) chemistry, which leads to unprecedented coordination polymers containing alcoholysis and/or hydrolysis “fragments” of the ligands, is also illustrated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Metal complexes as potential modulators of inflammatory and autoimmune responses

Abstract: Over the past few decades, the realm of inorganic medicinal chemistry has been dominated by the study of the anti-cancer properties of transition metal complexes, particularly those based on platinum or ruthenium. However, comparatively less attention has been focused on the development of metal complexes for the treatment of inflammatory or autoimmune diseases. Metal complexes possess a number of advantages that render them as attractive alternatives to organic small molecules for the development of therapeutic agents. In this perspective, we highlight recent examples in the development of transition metal complexes as modulators of inflammatory and autoimmune responses. The studies presented here serve to highlight the potential of transition metal complexes in modulating inflammatory or immune pathways in cells.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in Metal Complexes and Their Effect at the Cellular Level

Abstract: The nonsteroidal anti-inflammatory drugs (NSAIDs) make up a great group of drugs that provide benefits in the prevention of cancers. Coordinated metal ions with NSAIDs provide advantages over the drugs themselves. The metal complexes of NSAIDs display a range of biological activities quite often inaccessible to the original NSAID ligands. NSAIDs-metal complexes have molecular properties different from those of the parent drugs. Thus, if a given NSAIDs-metal complex remains intact in the biological medium its biological target is almost invariably different from the original NSAID target. This review includes results obtained on the antibacterial and antiproliferative activities of metal-NSAIDs complexes and their interaction with intracellular components. The study shows that the molecular weights of metal complexes containing the same NSAID are linearly related to their IC50 values against MCF-7 cells. Moreover, compounds with low molecular weight strongly bind to DNA.

Breast Cancer Stem Cell Potent Copper(II) – Non-steroidal Anti-Inflammatory Drug Complexes

Abstract: The breast cancer stem cell (CSC) potency of a series of copper(II)-phenanthroline complexes containing the nonsteroidal anti-inflammatory drug (NSAID), indomethacin, is reported. The most effective copper(II) complex in this series, 4, selectivity kills breast CSC-enriched HMLER-shEcad cells over breast CSC-depleted HMLER cells. Furthermore, 4 reduces the formation, size, and viability of mammospheres, to a greater extent than salinomycin, a potassium ionophore known to selectively inhibit CSCs. Mechanistic studies revealed that the CSC-specificity observed for 4 arises from its ability to generate intracellular reactive oxygen species (ROS) and inhibit cyclooxygenase-2 (COX-2), an enzyme that is overexpressed in breast CSCs. The former induces DNA damage, activates JNK and p38 pathways, and leads to apoptosis.