Axial-ligation and macrocyclization of novel (E,E)-dioximes of nickel(II) palladium(II), platinum(II) and cobalt(III)

Summary The synthesis and characterization of new Ni^II, Pd^II, Pt^II and Co^III complexes, with the BF _inf2 ^sup+ -bridged,bis(-di-oximato) ligands are described. The initially formed six-coordinate hydrogen-bonded macrocycles, were used as metal templates to prepare the corresponding BF _inf2 ^sup+ - capped macrocycles. The complexes were characterized by¹H-n.m.r. and i.r. spectroscopy, and by elemental analysis.     

Mass spectral studies of some 1,2,4-oxa-(thia)diazol-5(4H)-ones(thiones)

Electron ionization mass spectra of some 3,4-disubstituted 1,2,4-oxadiazole-5(4H)-thiones, thiadiazol-5(4H)-ones and thiadiazole-5(4H)-thiones are reported and fragmentation pathways of their molecular ions are studied in view of metastable ion experiments and accurate mass measurements. The main fragmentation route of the compounds under investigation is retro 1,3-dipolar cycloaddition.     

Synthesis and Characterization of Mono- and Trinuclear Complexes of BF2+ Bridged Macrocycles

Dibenzo[e,k]-2,3-bis(hydroxyimino)-1,4-dithia-7,10-diaza-2,3,8,9-tetrahydrocyclododecine (H₂L) has been prepared from 1,2-bis(o-mercaptoanilino) ethane ( 4 ) and (E,E)-dichloroglyoxime. A mononuclear complex with a metal: ligand ratio of 1:2 has been isolated for cobalt(III). The Co^III complex of H₂L has been prepared with L′ = 2,6-lutidine, and with a chlorine ion as axial ligands. In addition to that, the synthesis of a new cobalt complex which contains BF₂⁺ bridges is achieved with the bis(E,E)-dioxime ligand. The trinuclear complex of this Co^III complex has been obtained by the reaction of BF₂⁺ bridged Co^III complex with Pd[bis(benzonitrile)]Cl₂. The structures of these complexes and (E,E)-dioxime were identified by using elemental analysis, ¹H and ¹³C-NMR, IR and MS spectral data.     

A new vicinal-dioxime and its mono and trinuclear complexes containing the monoazatetraoxa macrocyclic moiety

Mononuclear [Co(HL)2LCl)], [Co(LBF2)2LCl] or [Cu-(HL)2] H2L = {N,N-bis (4-N-phenylaza [15]crown-5)diaminoglyoxime} and a trinuclear, [Cu(L)2(CuL)2](NO3)2, complex of the ligand were synthesized and characterized. The mononuclear copper(II) species coordinates to two copper(II) ions through the deprotonated oximate oxygens to yield a trinuclear structure cis-bridged by the oximate groups, with 1,10-phenanthroline as an end-cap ligand. The terminal copper adopts an essentially planar configuration with the nitrogen atoms of H2L. The structure of the ligand and its complexes is proposed and formulated according to the elemental analyses, 1H- and 13C-n.m.r, i.r. and m.s. spectral data.     

Determination of carotenoids in two algae species from the saline water of Kapulukaya reservoir by HPLC

The local algae species, Chlorella vulgaris and Scenedesmus regularis, from a highly saline water body of Kapulukaya Reservoir were isolated to analyze their carotenoid composition and content using HPLC method. The gradient solvent system of methanol–acetonitrile–water (84:14:2, v/v/v) and methylene chloride (100%), used to resolve a range of carotenoids from the saponified cells, proved an acceptable separation as inferred from the retention factor (k) ranging between 0.75 and 7.76 and the separation factor (α) values greater than 1. Resolution peaks assigned to carotenoids, 21 for C. vulgaris extracts and 22 for S. regularis extracts, were reached within the duration time of 45?min. Main carotenoids identified either tentatively or positively were all-trans-lutein, 9- or 9′-cis-lutein, 13- or 13′-cis-lutein, cis-lutein, All-trans-α-carotene, 9- or 9′-cis-α-carotene, All-trans-β-carotene, 9- or 9′-cis-β-carotene in the species except for all-trans-β-cryptoxanthin found only in S. regularis. Auroxanthin, neochrome, neoxanthin, and cis-neoxanthin were identified as epoxy-containing compounds. Quantitatively, C. vulgaris was distinguished to have greater amount of lutein and cis-isomers (2.74?mg/g), 77.89% while S. regularis was predominated by β-carotene and cis isomers as major component, being 80.72% (5.76?mg/g) in total carotenoids (TC). In terms of total carotenoids, the species were considered to be efficient sources for further practical applications.     

Studies on the Synthesis of bis(Benzo diaza 23-crown-7) and its Complexes with K+, Mg2+, Ca2+ and Ba2+ Perchlorates

A novel (E,E)-dioxime (H2L) containing a 23-membered macrocyclic ionophore was synthesized from the reaction of 2,3-(4-aminobenzo)-1,4,11,14,17-pentaoxa-6,22-dioxo-7,21-diaza-cyclotricosane-2-ene (5) prepared from 2,3-(4-nitrobenzo)-1,4,11,14,17-pentaoxa-6,22-dioxo-7,21-diazacyclotricosane-2-ene (4) and cyanogen di-N-oxide (6). H2L encapsulates and coordinates to alkaline earth metal cations via the oxygen atom to form complexes, H2L2MX (M = K+, Mg2+, Ca2+ and Ba2+; X = ClO4-). After the complexation with alkaline earth metal cations, 1H-NMR, 13C-NMR and IR data were obtained and a comparison of these spectral data is presented.     

Novel quasi‐scorpionate ligand structures based on a bis‐N‐heterocyclic carbene chelate core: synthesis,complexation and catalysis

A series of novel quasi‐scorpionate CNC donor ligands, MeC(2‐C₅H₄N){CH₂(imidazole‐R)} (R = methyl, n‐butyl, n‐propenyl), in which a chelating bis(NHC) core is supplemented by a hemi‐labile pyridyl donor, were prepared. The coordination chemistry of these ligands was investigated with silver, palladium, rhodium and iridium. The single crystal X‐ray structures of [Rh(NC₂^Me)(COD)]Cl 8a and [Ir(NC₂^Pr)(COD)]Br 9b were determined. The catalytic potential of the rhodium and iridium complexes was assessed in the transfer hydrogenation of ketones; the iridium complexes, which show superior performance, form very effective and stable catalysts. Copyright © 2011 John Wiley & Sons, Ltd.     

Determining the wettability of granular alumina by aluminum–magnesium alloys using the infiltration method

Wettability of the granular bed media influences the efficiency of aluminum filtration. This project was undertaken to develop a method for determining the wettability of the granular media in order to evaluate its suitability for filtration. The wetting characteristics of different granular alumina particles by aluminum–magnesium alloys were studied using the infiltration method. The contact angles for rough as well as smooth surfaces were determined, and alumina particles were classified according to their wetting characteristics. The results were consistent and showed that it is possible to differentiate the wetting characteristics of different alumina samples with the infiltration method. A capillary model based on the energy balance was developed to analyze the experimental data. The model uses an average capillary pore size. For one type of alumina, this model was extended to carry out the analysis using a capillary pore size distribution. Similar results were found in both cases. This paper describes the experimental and modeling work, and the results are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

A New And Convenient Synthesis Of Some Substituted Thiohydantoins

3-Substituted thiohydantoins (2a-g) were synthesized in satisfactory yields by the reaction of N-substituted thioureas (la-g) with chloroacetylchloride in the presence of triethylamine under reflux in dioxane. S-Alkylated products (7, 8) were obtained from the reaction of 3-p-tolyl -thiohydantoin (2d) with p-nitrobenzylchloride and 3-phenyl-5-chloromethyl-I,2,4-oxadiazole.     

A Novel Synthesis of DL-proto-, and DL-vibo-Quercitol via 1, 4-Cyclohexadiene

Photooxygenation of 1, 4-cyclohexadiene 3 followed by reduction with LiAlH₄ or thiourea gave (25/1)-cyclohex-3-ene-triol 7a. trans-Hydroxylation of triol 7a with three different methods afforded both of proto-quercitol la and vibo-quercitol 2a.