Synthesis and spectroscopic studies of platinum(II) complexes of N,N′-dicyclohexylethylenediamine

The platinum(II) complexes of the formula [Pt(DCHEDA)X₂], where DCHEDA is N,N′-dicyclohexylethylenediamine and X⁻ is CL⁻, Br⁻, I⁻, 0.5C₂O₄²⁻ (oxalate), 0.5C₃H₂O₄²⁻ (malonate), 0.5C₉H₄O₆²⁻ (4-carboxyphthalate), 0.5S₂O₃²⁻ or 0.5SO₄²⁻, have been synthesized and characterized by UVVis, IR, and ¹H NMR spectral techniques. All the above complexes are non-electrolytes in DMF/H₂O, except the sulphate complex which becomes a 1:1 electrolyte after incubation for 24 h at 28 °C. The halide complexes were also studied by X-ray photoelectron spectroscopy and these data suggest that there is π-bonding from platinum to halide in these complexes. The oxalate, malonate and sulphate bind in their complexes as bidentate ligands to platinum through two oxygen atoms whereas the thiosulphate in its complex binds as a bidentate ligand to platinum through one oxygen atom and one sulphur atom.     

Reactivity of platina-β-diketones towards chelating nitrogen and sulfur donors: formation of acyl(hydrido)platinum(IV) and acyl(chloro)platinum(II) complexes

The platina-β-diketone [Pt₂{(COMe)₂H}₂(μ-Cl)₂] (1) was found to react with chelating N,N-ligands 2(R^′NCR)C₅H₄N (R/R^′=Ph/OH, H/Ph, Me/Ph) to form acyl(hydrido)platinum(IV) complexes [Pt(COMe)₂Cl(H){2-(R^′NCR)C₅H₄N}] (R/R^′=Ph/OH 2a; H/Ph 2b; Me/Ph (2c)). Reactions of complex 1 with chelating S,S- and N,S-donors (RS-CH₂-CH₂-SR, 2-(RSCH₂)C₅H₄N, R=Et, Ph, t-Bu) afforded acyl(chloro)platinum(II) complexes [Pt(COMe)Cl(RSCH₂CH₂SR)] (R=Et, 3a; Ph, 3b; t-Bu, 3c) and [Pt(COMe)Cl{2-(RSCH₂)C₅H₄N}] (R=Et, 4a; Ph, 4b; t-Bu, 4c), respectively. All complexes were fully characterized by microanalysis, IR and NMR (¹H, ¹³C) spectroscopy. Furthermore, molecular structures of complexes 3b and 4b were determined by single-crystal X-ray diffraction analyses revealing close to square-planar configuration. In complex 4b the acetyl ligand is trans to pyridine N atom (configuration index SP-4-2). The reactions are discussed in terms of consecutive oxidative addition and reductive elimination reactions.     

Tabanidae (Diptera) of State of Maranhão, Brazil II. Description of Esenbeckia (Esenbeckia) rafaeli, sp. nov

Esenbeckia (Esenbeckia) rafaeli, sp.nov. is described and figured from nine specimens collected in Carolina, state of Maranh?o, Brazil. The new species is compared with the species Esenbeckia (Esenbeckia) laticlava Wilkerson & Fairchild, 1983; Esenbeckia (Esenbeckia) bitriangulata Lutz & Castro, 1935 e Esenbeckia (Esenbeckia) enderleini Kr?ber, 1931.     

Synthesis, crystal structure and pH dependent cytotoxicity of (SP-4-2)-bis(2-aminoethanolato-κN,O)platinum(II) - a representative of novel pH sensitive anticancer platinum complexes

Solid tumors are often hypoxic and consequently the pH in the tumoral tissue is decreasing with increasing tumor size (pH 5.5-7.4 in solid tumors versus pH 7.4 in normal tissues). This marked difference in pH value is a problem for weak base organic drugs and could advantageously be used for the introduction of pH sensitive anticancer platinum drugs. Synthesis and structure determination of (SP-4-2)-bis(2-aminoethanolato-κ²N,O)platinum(II), its binding behavior to 5^′-GMP and its cytotoxicity against cisplatin sensitive cell lines under standard pH screening conditions (pH 7.4) as well as in acidified cell culture medium (pH 6.0) mimicking the conditions in a number of solid tumors is presented. There is evidence that this concept in anticancer platinum therapy, namely administration of rather unreactive drugs and activation under acidic pH conditions, can be realized.     

Synthesis and crystal structures of platinum (II) complexes with phosphine sulfide: cis-Dichloro[dimethylsulfoxide](triphenylphosphine sulfide) platinum (II) and (−)-cis-dichloro[(S)-methyl-p-tolylsulfoxide](triphenylphosphine sulfide) platinum (II)

The addition of triphenylphosphine sulfide (Ph₃PS) to bis-sulfoxide platinum (II) complexes [Pt(Me₂SO)₂Cl₂] and (−)-[Pt(Me-p-TolSO)₂Cl₂] yields mixed ligand complexes [Pt(Ph₃PS)(Me₂SO)Cl₂] (1) and (−)-[Pt(Ph₃PS)(Me-p-TolSO)Cl₂] (2), which are effective catalysts for hydrosilylation reaction. These mixed-ligand complexes were obtained in crystal state and analyzed by X-ray diffraction, ¹H, ³¹P and ¹⁹⁵Pt NMR; 2 was also studied by circular dichroism spectroscopy. Both complexes exist in CDCl₃ solution as a dynamic equilibrium of two geometric isomers with an approximate 1:10 ratio, but only cis-isomer is obtained on crystallization. The X-ray structures of the complexes have classical geometry, and phosphine sulfide and sulfoxides are coordinated via sulfur. The new structural data for simple platinum–Ph₃PS coordination bond, unaffected by chelation or bridging, were evaluated. The lengths of this bond are 2.300(4) Å in 1 and 2.305(3) Å in 2, respectively. PtSP angle equals 105.7(2)° in 1 and 104.05(13)° in 2, the PtSP plane is almost perpendicular to the coordination plane. The static trans-influence of Ph₃PS is estimated to be strong and close to that of S-coordinated Me₂SO. The complex 2 exhibits strong circular dichroism at a wavelength below 330 nm, caused both by inherent Me-p-TolSO stereogenic center and induced asymmetry of Ph₃PS.     

Dinuclear compounds with a μ-cyano ligand. Part XIII. Synthesis,characterization and solid state kinetics of the formation of (μ-cyano)(tricyanometal(II))pentaamminerhodium(III) and iridium(III) (metal(II) = nickel,palladium, platinum). Influence of the PtPt interactions

Six new dinuclear complexes of (μ-cyano)(tricyanometal(II))pentaamminerhodium(III) or iridium(III), metal(II) being nickel, palladium and platinum, have been obtained by solid state reaction of the tetracyanometallate(II) of aquopentaamminerhodium(III) and iridium(III), respectively. All these complexes have been characterized by chemical analysis, electronic and IR spectra and TG measurements. The kinetics of the solid-state deaquation-anation has been studied by thermogravimetric measurements under both nonisothermal and isothermal conditions. The activation energies so obtained are 105.3 and 107.7 kJ/mol for the Ni compounds; 115.0 and 118.1 kJ/mol for the Pd compounds and 90.2 and 92.2 kJ/ mol for the Pt compounds. These low values of activation energy can indicate an S_N1 dissociative mechanism with an activated complex of square- based-pyramidal geometry. The marked difference in the kinetic parameters between the Ni, Pd compounds and Pt compounds may be explained in terms of Pt-Pt association in the crystal lattice, which causes distortion and allows the water molecules to escape easily from the crystal structure. These Pt-Pt interactions are shown in the electronic spectrum by the appearance of a very strong band at about 355 nm in the solid state and at about 330 nm and 300 nm in solution.     

Synthesis of new (σ-N,N′-diazadiene)(η-alkene)platinum(0) compounds

Novel, thermally stable, dark-red to orange Pt⁰(σ²-N,N′-diazadiene)(η²-alkene) compounds have been synthesized in good yields from Pt⁰(COD)₂ or Pt⁰(NBE)₃, by stepwise substitution of the respective dienes or alkenes by an electron-poor alkene (dimethyl fumarate, maleic anhydride or fumaronitrile), followed by the appropriate diazadiene ligand in dry diethyl ether at 20 °C (diazadiene=various N,N′-disubstitued-1,4-diaza-1,3-dienes). The complex Pt(DBA)₂ is less suited as a precursor for the synthesis of Pt⁰(σ²-N,N′-diazadiene)(η²-alkene) compounds. These zerovalent Pt(diazadiene)(η²-alkene) compounds constitute a useful category of starting materials for synthetic organoplatinum chemistry and catalysis.     

Neotropical Monogenoidea. 32. Cacatuocotyle paranaensis n. g., n. sp. (Dactylogyridae,Ancyrocephalinae) from Characidium spp. (Teleostei,Characidae) from the State of Paraná, Brazil

Cacatuocotyle paranaensis n. sp. (Dactylogyridae, Ancyrocephalinae) is described from the gills of the characid fishes Characidium lanei Travassos and C. pterostictum Gomes collected from two streams on the coast of the State of Paraná, Brazil. Cacatuocotyle n. g. is proposed for species possessing a single cephalic lobe (terminal), one pair of head organs, a convex haptor with thickened muscular anterior margins, one anchor-bar complex (ventral), seven pairs of ventral hooks (one pair associated with the anchor shafts; one central pair anterior to the bar; five submarginal bilateral pairs) and a sinistral vaginal aperture.     

Revision of “Phyllobrotica” from Taiwan with description of Jolibrotica gen. n. (Coleoptera,Chrysomelidae, Galerucinae)

All Taiwanese species formerly classified the genus Phyllobrotica Chevrolat, 1836 are revised. Jolibrotica Lee & Bezděk, gen. n., is described for Phyllobrotica sauteri (Chûjô, 1935) (Taiwan, China: Guangxi) and Phyllobrotica chujoi Kimoto, 1969 (Taiwan). Phyllobrotica shirozui Kimoto, 1969 is transferred to the genus Haplosomoides. All species are redescribed and their diagnostic characters illustrated.     

Reactions of VCl3, VCl4 and TiX4 (XCl,Br) with benzofuroxan and its 5-methyl-, 5-chloro- and 5-methoxi-derivatives. I.

By means of the reaction between VCl₃ and benzofuroxan the compound VCl₃·2C₆H₄N₂O₂ was obtained, while in reaction with TiX₄ (XCl, Br) the compounds with stoichiometry TiX₄·C₆H₄N₂O₂ (X Cl, Br) were obtained.Furthermore, with some benzofuroxan derivatives (5-methyl, 5-chloro and 5-methoxi) the complexes MCl₄·2YC₆H₃N₂O₂ (MTi, V; YCH₃O, Cl, CH₃), TiCl₄·YC₆H₃N₂O₂ (YCH₃O, CH₃) and TiBr₄·YC₆H₃N₂O₂ (YCH₃O, Cl, CH₃) have been isolated.The compounds were characterized by elementary analysis, cryoscopic molecular weight determination in nitrobenzene, magnetic measurements and IR, Vis and EPR spectroscopy.     

Ecology,development and pathogenicity of Buddenbrockia plumatellae Schröder, 1910 (Myxozoa,Malacosporea) (syn. Tetracapsula bryozoides) and establishment of Tetracapsuloides n. gen. for Tetracapsula bryosalmonae

Buddenbrockia plumatellae, an enigmatic worm-like myxozoan, was observed as continuously writhing free and attached 'worms' and as free mature spores in the coelom of the freshwater bryozoans Plumatella fungosa, Hyalinella punctata, and Fredericella sp. 'Worm' numbers could double every three days. 'Worms' and spores could be expelled from colonies by external pressure. Some mature 'worms' exited actively, entraining release of free spores, and gradually ceased movement outside the host. Bryozoans sealed off infected regions of the colony. Infected colonies grew slowly, produced no statoblasts, and eventually regressed and died. Transmission was not achieved and prevalence was low. Electron microscopy of 'worms' revealed a single layer of mural cells on a fibrous basal lamina overlying four longitudinal muscle blocks and an inner sheet of two types of proliferating cells, an organization indicative of the bilaterian ancestry of the Myxozoa. Primary type A cells were attached directly by striated tubules to mural cells at positions between muscle blocks. Secondary type A cells had a secretory function. Type B cells underwent meiosis and subsequently developed to typical malacosporean myxozoan spores filling the internal cavity of the 'worms'. External tubes were formed during capsulogenesis in 'worms' from Fredericella sp. Tetracapsula bryozoides is synonymised with Buddenbrockia plumatellae and a new genus is proposed for Tetracapsula bryosalmonae.     

Morphological and molecular reinvestigation of acanthoecid species III. – Kalathoeca cupula (Leadbeater, 1972) gen. et comb. nov. (=Stephanoeca cupula (Leadbeater) Thomsen, 1988)

Based on a further re-examination of loricate choanoflagellate species with detailed morphological (SEM/TEM) and molecular data of the SSU and LSU rRNA, the present study aims to give new insights for Stephanoeca cupula. In contrast to the original allocation within the family of tectiform reproducing species, morphological and molecular data of S. cupula sensu Leadbeater, 1972 points towards an affiliation within the nudiform reproducing family. Based on these new data, we here erect the nudiform genus Kalathoeca with its type species K. cupula gen. et comb. nov. Our data challenges morphological species assignments, as K. cupula shares its morphological lorica characteristics with tectiform reproducing species of Stephanoeca sensu stricto. Kalathoeca cupula is an interesting candidate for further investigating and understanding the evolutionary relationship of tectiform and nudiform reproducing species.Stephanoeca cupula sensu Thomsen, 1988 has been morphologically re-examined based on the renewed understanding of the morphological variability associated with S. cupula sensu Leadbeater, 1972 (=K. cupula), allowing us now to distribute the different morphological forms investigated within K. cupula and Pseudostephanoeca quasicupula.     

Mechanism of killing of HeLa cells by the antitumor sulfonylurea,N-(4-methylphenylsulfonyl)-N′-(4-chlorophenyl)urea (LY 181984)

Summary The antitumor sulfonylureas appear to inhibit both mitochondrial activity in susceptible human colon lines and to inhibit the oxidation of NADH by isolated plasma membrane vesicles from HeLa cells. The results reported here describe the morphological appearance of HeLa cells treated with the antitumor sulfonylurea N-(4-methylphenylsulfonyl)-N-(4-chlorophenyl)urea (LY181984). The cells remain viable for several days although the rate of increase in cell number is slowed especially at high concentrations of the drug. Cells become smaller with normal nuclei or maintain a normal size but contain multiple or enlarged nuclei. The morphological observations suggest that the drug may somehow interfere with the ability of the cells to enlarge following cytokinesis. Between 72 and 96 h, the cells begin to die. Cell death is accompanied by a condensed and fragmented appearance of the nuclear DNA as revealed by fluorescence microscopy with 4,6-diamidino-2-phenylindole suggestive of apoptosis. Early transients in loss of pH control (4 min after sulfonylurea addition) and an increase in cytoplasmic calcium (4 h after sulfonylurea addition) were observed but were small and perhaps secondary to the mechanism responsible for the failure of the cells to grow and ensuing cell death.     

Neotropical Monogenoidea 64. Cosmetocleithrum falsunilatum sp. n. (Monogenoidea,Dactylogyridae) parasite of the gills of Megalodoras uranoscopus (Siluriformes,Doradidae) from the Solimões river,near Iquitos,Peru

Systematic Parasitology - Megalodoras uranoscopus (Eigenmann & Eigenmann) (Siluriformes, Doradidae) (the giant-talking catfish or the giant-raphael catfish), from the...