Substituent‐Free Gallium by Hydrogenolysis of Coordinated GaCp*: Synthesis and Structure of Highly Fluxional [Ru2(Ga)(GaCp*)7(H)3]

All change : Complete ligand exchange through the hydrogenation of [Ru(η⁴‐cod)(η⁶‐cot)] in the presence of GaCp* under mild conditions leads to the title complex featuring a “naked” gallium atom bridging two ruthenium centers (see structure: C white, Ga blue, Ru red). This cluster can be considered as a trapped intermediate on the way to mixed‐metal nanoparticles; cot=1,3,5‐cyclooctatriene; cod=1,5‐cyclooctadiene, Cp*=C₅Me₅.

     

Cover Picture: Substituent‐Free Gallium by Hydrogenolysis of Coordinated GaCp*: Synthesis and Structure of Highly Fluxional [Ru2(Ga)(GaCp*)7(H)3] (Angew. Chem. Int. Ed. 21/2009)

Soft skin, hard core …? is the basic principle for the formation of a nano‐alloy from molecular precursors. The co‐hydrogenolysis of ruthenium complexes in presence of GaCp* gives the isolable key intermediate [Ru₂(Ga)(GaCp*)₇(H)₃] featuring a substituent‐free bridging gallium atom. From this “embryonic” species Ru/Ga phases are formed by complete cleavage of the protective Cp* shell (depicted as an eggshell in the Cover picture), as described by R. A. Fischer et al. in their Communication on page 3872 ff.

     

Imprinted polymer particles for iron uptake: Synthesis, characterization and analytical applications

This work reports the preparation of molecularly imprinted polymer particles for selective extraction and determination of iron ions from aqueous media. The polymer particles were synthesized from Fe(NO₃)₃, morin, 4-vinylpyridine, ethyleneglycoldimethacrylate, and 2,2′-azobisisobutyronitrile and characterized by IR and DSC both prior to and after removing the Fe-morin complex by leaching with HCl. The effect of different parameters, such as pH, adsorption and desorption time, type and minimum amount of eluent for removing the complex from polymer was evaluated and optimized. The proposed method is characterized by the detection limit of 3.1 µg l^?1 anddynamic linear range of 25 to 200 µg l^?1, with the relative standard deviation less than 8.8%. The method was applied to the recovery and determination of iron ions in a few real samples.     

Synthesis and characterization of UV-irradiated silver/montmorillonite nanocomposites

We have successfully developed a simple method for preparing silver nanoparticles (Ag NPs) using UV irradiation of AgNO₃ in the interlamellar space of a montmorillonite (MMT) without any reducing agent or heat treatment. The properties of Ag/MMT nanocomposites were studied as a function of the UV irradiation period. UV irradiation disintegrated the Ag NPs into smaller size until a relatively stable size and size distribution were achieved. The results from UV–vis spectroscopy show that particles size of Ag NPs decrease with the increase of irradiation period. The crystalline structure of Ag NPs was determined by powder X-ray diffraction (PXRD).     

Synthesis and characterization of Co(II), Ni(II), Zn(II) and Cu(II) complexes with a new tetraazamacrocyclic Schiff base ligand containing a piperazine moiety: X-ray crystal structure determination of the Co(II) complex

Two macrocyclic Schiff base ligands, L¹ [1+1] and L² [2+2], have been obtained in a one-pot cyclocondensation of 1,4-bis(2-formylphenyl)piperazine and 1,3-diaminopropane. Unfortunately, because of the low solubility of both ligands, their separation was unsuccessful. In the direct reaction of these mixed ligands (L¹ and L²) and the appropriate metal ions only [CoL¹(NO₃)]ClO₄, [NiL¹](ClO₄)₂, [CuL¹](ClO₄)₂ and [ZnL¹(NO₃)]ClO₄ complexes have been isolated. All the complexes were characterized by elemental analyses, IR, FAB-MS, conductivity measurements and in the case of the [ZnL¹(NO₃)]ClO₄ complex with NMR spectroscopy.     

A Modified and Green Procedure for the Synthesis of β-Amido Ketones Using a BrΦnsted-Acidic Ionic Liquid as Novel and Reusable Catalyst

A green and improved method for the synthesis of β‐amido ketones through one‐pot multi‐component reaction of an enolizable ketone, aryl aldehyde, acetonitrile or benzonitrile in the presence of trimethylsilyl chloride using 3‐methyl‐1‐(4‐sulfonic acid)butylimidazolium hydrogen sulfate [(CH₂)₄SO₃HMIM][HSO₄], a Br?nsted‐acidic ionic liquid, as an effective and recyclable catalyst is described. The present methodology offers several advantages such as simple procedure with an easy work‐up, relatively short reaction time, and good to excellent yields.     

Synthesis of some novel sulfonyl ester derivatives derived from d-mannitol

The preparation of sulfonate-derivatives of d-mannitol i.e. 1,2:3,4-di-O-isopropylidene-3,4-di-O-p-toluenesulfonate-d-mannitol (3a), 1,2:3,4-di-O-isopropylidene-3,4-di-O-methanesulfonate-d-mannitol (3b), and 1, 2:3,4-di-O-isopropylidene-3,4-di-O-trifluoromethanesulfonate-d-mannitol (3c) is described. Full characterization and methodologies of these sulfonate-d-mannitol derivatives have been described as well.     

Tanacetamide D: A New Ceramide from Tanacetum artemisioides

One new ceramide (=long‐chain base linked to a fatty acid via an amide bond), tanacetamide D ( 1 ), was isolated from Tanacetum artemisioides. Besides this, the two known constituents 5‐demethylnobiletin ( 2 ) and 5‐hydroxy‐3,6,7,8,3′,4′‐hexamethoxyflavone ( 3 ) were isolated for the first time from this species. The structure elucidation of the isolated compounds were based primarily on 2D‐NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple‐quantum coherence (HMQC), heteronuclear multiple‐bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY) experiments.     

Herbicidal activity of flavonoids of mango leaves against Parthenium hysterophorus L

This study was undertaken to investigate the herbicidal activity of mango (Mangifera indica L.) leaves against parthenium weed (Parthenium hysterophorus L.). The aqueous leaf extract at 15% concentration (on fresh weight basis) significantly reduced germination, shoot length and the shoot and root biomasses of parthenium seedlings. In a leaf residue incorporation pot trial, 2% residue incorporation treatment significantly suppressed the root and shoot biomasses of parthenium, while a 5% residue treatment completely stopped the growth of the weed. Five flavonoids, namely (-)-epicatechin-3-O-β-glucopyranoside (1), 5-hydroxy-3-(4-hydroxyphenyl)pyrano[3,2-g]chromene-4(8H)-one (2), 6-(p-hydroxybenzyl)taxifolin-7-O-β-D-glucoside (tricuspid) (3), quercetin-3-O-α-glucopyranosyl-(1 → 2)-β-D-glucopyranoside (4) and (-)-epicatechin(2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H chromene-3,5,7-triol (5) were isolated from mango leaves. In a laboratory bioassay, 50 ppm solution of compounds 3 and 4 caused yellowing of the parthenium seedlings. A 250 ppm solution of compound 4 also significantly reduced germination and the root and shoot lengths of parthenium seedlings. This study concludes that compound 4 exhibits herbicidal activity against parthenium weed.     

Antifungal activity of flavonoids isolated from mango (Mangifera indica L.) leaves

Five flavonoids, namely (-)-epicatechin-3-O-β-glucopyranoside (1), 5-hydroxy-3-(4-hydroxylphenyl)pyrano[3,2-g]chromene-4(8H)-one (2), 6-(p-hydroxybenzyl)taxifolin-7-O-β-D-glucoside (tricuspid) (3), quercetin-3-O-α-glucopyranosyl-(1 → 2)-β-D-glucopyranoside (4) and (-)-epicatechin(2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H-chromene-3,5,7-triol (5), were isolated from the leaves of mango (Mangifera indica L.). Antifungal activity of these compounds was evaluated against five fungal species, namely Alternaria alternata (Fr.) Keissler, Aspergillus fumigatus Fresenius, Aspergillus niger van Tieghem, Macrophomina phaseolina (Tassi) Goid. and Penicillium citrii. Six concentrations, namely 100, 300, 500, 700, 900 and 1000 ppm of each of the five flavonoids were employed by means of the poisoned medium technique. All concentrations of the five test flavonoids significantly suppressed fungal growth. However, the specificity of different test compounds was evident against different fungal species. In general, antifungal activity of the flavonoids was gradually increased by increasing their concentrations. The highest concentration (of 1000 ppm) of compounds 1-5 reduced the growth of different target fungal species by 63-97%, 56-96%, 76-99%, 76-98% and 82-96%, respectively.