New copper(II) complexes with isoconazole: Synthesis, structures and biological properties

There is an increasing demand for novel metal-based complexes with biologically relevant molecules in technology and medicine. Three new Cu(II) coordination compounds with antifungal agent isoconazole (L), namely mononuclear complexes CuCl2(L)(2) (1), and Cu(O2CMe)(2)(L)(2)center dot 2H(2)O (2) and coordination polymer Cu(pht)(L)(2)(n) (3) (where H(2)pht - o-phthalic acid) were synthesized and characterized by IR spectroscopy, thermogravimetric analysis and X-ray crystallography. X-ray analysis showed that in all complexes, the isoconazole is coordinated to Cu(II) centres by a N atom of the imidazole fragment. In complex I, the square-planar environment of Cu(II) atoms is completed by two N atoms of isoconazole and two chloride ligands, whereas the Cu(II) atoms are coordinated by two N atoms from two isoconazole ligands and two O atoms from the different carboxylate residues: acetate in 2 and phthalate in 3. The formation of an infinite chain through the bridging phthalate ligand is observed in 3. The biosynthetic ability of micromycetes Aspergillus niger CNMN FD 10 in the presence of the prepared complexes 1-3 as well as the antifungal drug isoconazole were studied. Complexes 2 and 3 accelerate the biosynthesis of enzymes (beta-glucosidase, xylanase and endoglucanase) by this fungus. Moreover, a simplified and improved method for the preparation of isoconazole nitrate was developed.

Mononuclear Tetraamineplatinum(II) Complexes: Synthesis, Anticancer Activity, DNA Binding, and Cellular Uptake

The synthesis of three bis[(tert-butoxy)carbonyl]-protected (tetramine)dichloroplatinum complexes 2a – c of formula cis-[PtCl2(LL)] and of their cationic deprotected analogs 3a – c and their evaluation with respect to in vitro cytotoxicity, intramolecular stability, DNA binding, and cellular uptake is reported. The synthesis comprises the complexation of K2[PtCl4] with di-N-protected tetramines 1a – c to give 2a – c and subsequent acidolysis, yielding 3a – c. The cytotoxicity of the complexes is in direct relation to the length of the polyamine. Complexes 3a – c display a significant higher affinity for CT DNA as well as for cellular DNA in A2780 cells than cisplatin.

Photoassembly of the manganese cluster and oxygen evolution from monomeric and dimeric CP47 reaction center photosystem II complexes

Isolated subcomplexes of photosystem II from spinach (CP47RC), composed of D1, D2, cytochrome b559, CP47, and a number of hydrophobic small subunits but devoid of CP43 and the extrinsic proteins of the oxygen-evolving complex, were shown to reconstitute the Mn4Ca1Clx cluster of the water-splitting system and to evolve oxygen. The photoactivation process in CP47RC dimers proceeds by the same two-step mechanism as observed in PSII membranes and exhibits the same stoichiometry for Mn2+, but with a 10-fold lower affinity for Ca2+ and an increased susceptibility to photodamage. After the lower Ca2+ affinity and the 10-fold smaller absorption cross-section for photons in CP47 dimers is taken into account, the intrinsic rate constant for the rate-limiting calcium-dependent dark step is indistinguishable for the two systems. The monomeric form of CP47RC also showed capacity to photoactivate and catalyze water oxidation, but with lower activity than the dimeric form and increased susceptibility to photodamage. After optimization of the various parameters affecting the photoactivation process in dimeric CP47RC subcores, 18% of the complexes were functionally reconstituted and the quantum efficiency for oxygen production by reactivated centers approached 96% of that observed for reconstituted photosystem II-enriched membranes.

Production, specificity, and functionality of monoclonal antibodies to specific peptide–major histocompatibility complex class II complexes formed by processing of exogenous protein

Several unanswered questions in T cell immunobiology relating to intracellular processing or in vivo antigen presentation could be approached if convenient, specific, and sensitive reagents were available for detecting the peptide–major histocompatibility complex (MHC) class I or class II ligands recognized by αβ T cell receptors. For this reason, we have developed a method using homogeneously loaded peptide–MHC class II complexes to generate and select specific mAb reactive with these structures using hen egg lysozyme (HEL) and I-Ak as a model system. mAbs specific for either HEL-(46–61)–Ak or HEL-(116–129)–Ak have been isolated. They cross-react with a small subset of I-Ak molecules loaded with self peptides but can nonetheless be used for flow cytometry, immunoprecipitation, Western blotting, and intracellular immunofluorescence to detect specific HEL peptide–MHC class II complexes formed by either peptide exposure or natural processing of native HEL. An example of the utility of these reagents is provided herein by using one of the anti-HEL-(46–61)–Ak specific mAbs to visualize intracellular compartments where I-Ak is loaded with HEL-derived peptides early after antigen administration. Other uses, especially for in vivo tracking of specific ligand-bearing antigen-presenting cells, are discussed.

Expression of endogenous peptide-major histocompatibility complex class II complexes derived from invariant chain-antigen fusion proteins.

CD4+ T cells recognize major histocompatibility complex (MHC) class II-bound peptides that are primarily obtained from extracellular sources. Endogenously synthesized proteins that readily enter the MHC class I presentation pathway are generally excluded from the MHC class II presentation pathway. We show here that endogenously synthesized ovalbumin or hen egg lysozyme can be efficiently presented as peptide-MHC class II complexes when they are expressed as fusion proteins with the invariant chain (Ii). Similar to the wild-type Ii, the Ii-antigen fusion proteins were associated intracellularly with MHC molecules. Most efficient expression of endogenous peptide-MHC complex was obtained with fusion proteins that contained the endosomal targeting signal within the N-terminal cytoplasmic Ii residues but did not require the luminal residues of Ii that are known to bind MHC molecules. These results suggest that signals within the Ii can allow endogenously synthesized proteins to efficiently enter the MHC class II presentation pathway. They also suggest a strategy for identifying unknown antigens presented by MHC class II molecules.

Metal-complex ionosilicas: Cationic mesoporus silica with Ni(II) and Cu(II) complexes in their framework

Metal-complex ionosilicas with cationic complexes into the mesoporous silica framework were prepared using anionic surfactants. The electrostatic interaction between the anionic surfactant and the cationic metal complexes incorporated in the silica framework allows for the fine tuning of the mesoporous structure. The gentle procedure of synthesis developed and mild ion-exchange extraction of the surfactant, allowed a cleaner route for the immobilization of homogeneous cationic catalysts in mesoporous silica, while protecting the structural and chemical integrity of the metal complexes.

Enantioselective Synthesis of exo-4-Nitroprolinates from Nitro­alkenes and Azomethine Ylides Catalyzed by Chiral Phosphor­amidite·Silver(I) or Copper(II) Complexes

Chiral complexes formed by privileged phosphoramidites derived from chiral binol and optically pure Davies’ amines, and copper(II) triflate, silver(I) triflate or silver(I) benzoate are excellent catalysts for the general 1,3-dipolar cycloaddition between nitroalkenes and azomethine ylides generated from α-amino acid derived imino esters. These three methods can be conducted at room temperature to afford the exo-cycloadducts (4,5-trans-2,5-cis-4-nitroprolinates) with high diastereoselectivity and high enantioselectivity. In general, the three procedures are complementary but silver catalysts are more versatile and less sensitive to sterically congested starting materials.

Palladium(II) complexes with a phosphino-oxime ligand: synthesis, structure and applications to the catalytic rearrangement and dehydration of aldoximes

The treatment of [PdCl2(COD)] (COD = 1,5-cyclooctadiene) with 1 and 2 equivalents of 2-(diphenylphosphino)benzaldehyde oxime in dichloromethane at room temperature led to the selective formation of [PdCl2{κ2-(P,N)-2-Ph2PC6H4CH[double bond, length as m-dash]NOH}] (1) and [Pd{κ2-(P,N)-2-Ph2PC6H4CH[double bond, length as m-dash]NOH}2][Cl]2 (2), respectively, which represent the first examples of Pd(II) complexes containing a phosphino-oxime ligand. These compounds, whose structures were fully confirmed by X-ray diffraction methods, were active in the catalytic rearrangement of aldoximes. In particular, using 5 mol% complex 1, a large variety of aldoximes could be cleanly converted into the corresponding primary amides at 100 °C, employing water as solvent and without the assistance of any cocatalyst. Palladium nanoparticles are the active species in the rearrangement process. In addition, when the same reactions were performed employing acetonitrile as solvent, selective dehydration of the aldoximes to form the respective nitriles was observed. For comparative purposes, the catalytic behaviour of an oxime-derived palladacyclic complex has also been briefly evaluated.

Formation of mononuclear and chloro-bridged binuclear copper(II) complexes of patellamide D, a naturally occurring cyclic peptide: influence of anion and solvent

Patellamide D (patH(4)) is a cyclic octapeptide isolated from the ascidian Lissoclinum patella. The peptide possesses a 24-azacrown-8 macrocyclic structure containing two oxazoline and two thiazole rings, each separated by an amino acid. The present spectrophotometric, electron paramagnetic resonance (EPR) and mass spectral studies show that patellamide D reacts with CuCl, and triethylamine in acetonitrile to form mononuclear and binuclear copper(II) complexes containing chloride. Molecular modelling and EPR studies suggest that the chloride anion bridges the copper(II) ions in the binuclear complex [Cu-2(patH(2))(mu-Cl)](+). These results contrast with a previous study employing both base and methanol, the latter substituting for chloride in the copper(II) complexes en route to the stable mu-carbonato binuclear copper(II) complex [Cu-2 (patH(2))(mu-CO3)]. Solvent clearly plays an important role in both stabilising these metal ion complexes and influencing their chemical reactivities. (C) 2004 Elsevier Inc. All rights reserved.

Molecular mixed-valence cyanide bridged Co-III-Fe-II complexes

Cyano-bridged mixed-valence compounds have been known for a long time, i.e., Prussian Blue polymeric solids. Nevertheless, the interest in discrete complexes having a well-defined molecular nuclearity has emerged more recently. There are numerous examples of cyano-bridged mixed-valence complexes in the recent literature, as they show promising and useful applications in electrochromism, molecular magnetism and molecular electronics. In this paper, the reactivity, synthetic and structural chemistry, as well as some physical and chemical properties, of a series of discrete dinuclear mixed-valence cyano-bridged complexes of general formulae [LnCoIII(mu NC)Fe-II(CN)(5)](-) (L = pentadentate macrocyclic ligand) are reviewed. Special emphasis is given to the synthetic strategy, redox properties and metal-to-metal-charge-transfer (MMCT) band energy. Tuning the MMCT transition energy has been possible by changing the redox potential of the metal centers, both through structural and outer-sphere changes. The redox processes that involve the appearance and disappearance of these MMCT bands in the visible region have been dealt with in relation to the possible uses of the complexes. (c) 2004 Elsevier B.V. All rights reserved.