Chelatbildende Enaminoketone II. Synthese von symmetrischen Liganden

Syntheses of Bis-enaminoketones are described, which are able to form square planar chelates with transition metals. Tetra- and multidentate ligands were prepared from anilinomethylene derivatives of 1,3-dicarbonyl compounds and various diamines. Lipophilic ligands were prepared with respect to potential use as carriers in liquid membrane permeation. Incorporation of the ligands into a polymer (via a spacer group) was performed by radical polymerization.

     

Recent developments on 3-hydroxy-4-pyridinones with respect to their clinical applications: Mono and combined ligand approaches

There has been considerable research effort invested in the discovery and development of chelators for the treatment of serious pathological disorders associated with iron (or aluminium) overload in the past two decades. A series of 3-hydroxy-4-pyridinone (3,4-HP) iron-ligands, in particular bis-(3,4-HP)s and mono-(3,4-HP)s were developed by exploring their polydenticity and/or bifunctionality. These compounds were assessed for their physicochemical and biological properties such as the chelating ability for M³⁺ hard metal ions (M = Fe, Al, Ga), the lipophilicity (log P) and the metal-clearing efficiency (MCE) from most organs in mice pre-loaded with ⁶⁷Ga, as a model of Fe-overload. Although the solution chemistry and the in vivo studies have been performed with individual ligands, a ligand combination strategy with the bis- and mono-(3,4-HP) was adopted to improve the scavenger power based on differences on their cellular-compartment accessibility. The results lead to key recommendations useful in chelator design strategies because there are significant differences in chelating affinity and MCE in mice between the bis-HP and the mono-HP ligands. The extra-functional groups of the compounds have a profound effect on log P, MCE and organ distribution, and so they can be targeted to organs compromised in iron-overload disease, for example, the liver or the brain. The coadjuvation or synergistic effects of the ligand combination is supported by the observed improvements on metal excretion in bioassays.     

Terminale und verbrückende Koordination von Indium‐Indium‐Bindungen – bemerkenswerte Polymorphie an der Verbindung In2R2[(OCC6H5)2CH]2 [R = C(SiMe3)3]

Terminal and Bridging Coordination of Indium‐Indium Bonds – Remarkable Polymorphism with the Compound In₂R₂[(OCC₆H₅)₂CH]₂ [R = C(SiMe₃)₃] Treatment of the dimeric indium(II) subhalide (In₂R₂Cl₂)₂ ( 1 ) [R = C(SiMe₃)₃] with four equivalents of lithium dipivaloylmethanide or lithium dibenzoylmethanide afforded by the release of lithium chloride the corresponding diindium diacetylacetonates ( 2 and 3 ). The In‐In single bonds of the products were terminally coordinated by chelating acectylacetonato ligands and the bulky alkyl groups. Three different crystal structures were determined for the dibenzoylmethanide derivative 3 which in the solid state adopted trans and gauche conformations across the In‐In bonds. In contrast to the terminally arranged acetylacetonato ligands of compounds 2 and 3 alkylbenzoato ligands R‐COO^? (3,5‐dimethylbenzoate and p‐tert‐butylbenzoate) gave the bridging coordination of the In‐In bonds by two chelating carboxylato groups ( 4 and 5 ). This particular coordination caused a strong shortening of the In‐In bond length in 4 compared to the unsupported bonds in 2 and 3 (264.6 versus 274.7 to 279.3 pm).     

Study of interference of pharmaceuticals with complexing characteristics in solid phase microextraction of lead on chelating celluloses

Trace lead impurities of drugs in 1-5% solutions can be preconcentrated on imino diacetic acid-ethyl cellulose (IDAEC). The buffered sample was loaded onto a chelating cellulose minicolumn by flow injection followed by the nitric acid elution and graphite furnace atomic absorption spectrometry (GFAAS) determination. The detection limit of the procedure depending on the concentration of drug solution is in the range 2-10 ng g^− 1. The bonding of lead to various pharmaceutical compounds appeared in reduced rate during preconcentration according to the competition between ligands. The first step was focused on the determination of the stability constants of the lead-chelating cellulose species. In the second step, the sorption was estimated from different pharmaceutical matrices considering the lead-drug interaction. In the third experimental step estimated sorption was compared with the determined values for some medicines like aspartic acid, penicillamine, captopril, N-acetyl-cysteine and its pharmaceutical product, ACC 200.     

Hydrophile Polymergele mit reaktiven Gruppen, 2. Mitt.: Chelatharze auf Basis von Glucose- und Saccharosemethacrylaten

A widely applicable method for the preparation of chelating resins based on glucose- and sucrosemethacrylate-gels is described. Primary aromatic amino groups were bonded to the carrier by esterification with 4-nitrobenzoylchloride and subsequent reduction of the nitro groups with sodium dithionite. Diazotation and coupling with various chelating ligands (8-hydroxyquinoline, dithizone, anthranilic acid, salicylic acid and pyrogallol) afforded chelating resins with capacities of max. 1.7 mmol/g. Sucrosemethacrylate-gels were etherified with 4-nitrobenzylchloride, epichlorohydrin, 4-nitrophenyl glycide ether (IIb), acrylonitrile and 4-nitrophenylacrylamide (IVb). Reaction of the gels with IIb or IVb and subsequent reduction of the nitro groups yielded reactive carriers with ether-linked primary aromatic amino groups. Diazotation and coupling with 8-hydroxyquinoline yielded chelating resins. The capacities of the gels were 0.6–0.7 mmol/g and these resins were extremely stable to changes inpH.

     

Novel nitrogen ligands based on imidazole derivatives and their application in asymmetric catalysis

Recently prepared chiral amines have been used in the preparation of novel tridentate ligands based on an imidazole ring with an additional (hetero)ring. The synthesis was carried out by the reaction of chiral amines with suitable aldehydes (2-phenylimidazole-4-carbaldehyde, 2-hydroxybenzaldehyde or pyridine-2-carbaldehyde) under reductive conditions (H₂/Pd or NaBH₄). All ligands prepared showed strong hydrogen bonds in d₆-DMSO solution, which resulted in hindered imidazole tautomerism. The observed hindered tautomerism was studied by ¹H NMR spectroscopy. The structures of the prepared ligands were also confirmed by APCI mass spectroscopy. Both chiral amines and tridentate compounds have been applied as ligands in copper (II)-catalyzed nitroaldol reactions (Henry reaction). Various reaction conditions for the Henry reaction have been studied (influence of temperature, molar ratio, solvent or copper (II) precursors). The compounds prepared with the two imidazole rings showed fast reaction times and a reversal in enantioselectivity compared to other chiral amines.     

Hydrophile Polymergele mit reaktiven Gruppen, 5. Mitt.: Chelatharze mit phosphorhaltigen Ankergruppen auf Basis von Saccharosemethacrylaten

Phosphorus containing chelating resins were synthesized by reaction of sucrosemethacrylate gels with various dialkylester halides of phosphoric acid and thiophosphoric acid. The sorption capacities of the hydrophilic gels were found to be max. 3.7 mmol/g and equilibrium was achieved within 5 minutes. The recycle of adsorption and elution was found to be satisfactory for Zn²⁺ and Cu²⁺ whereas only 50% of the bonded Hg²⁺ could be recovered reversibly.

     

Latent ruthenium carbene complexes with six-membered N- and S-chelate rings

New ruthenium carbene complexes with chelating N- and S-benzylidene ligands were synthesized by the reactions of second- and third-generation Grubbs catalysts with ortho-vinylbenzyl-substituted amines or sulfides. These complexes were shown to exhibit catalytic activity in ring-opening metathesis polymerization and ring-closing metathesis.     

Determination of iron and copper in seawater at pH 1.7 with a new commercially available chelating resin, NTA Superflow

The use of a commercially available chelating resin with NTA-type functional groups for concentration of trace metals from seawater is described. Trace metal recoveries from this NTA Superflow chelating resin are pH dependent. At a pH of ≤2 only iron(III) and copper are quantitatively recovered from the resin. Iron(II) cannot be quantitatively recovered from this resin below a pH of 5. However, oxidation of acidified seawater samples (pH 1.7) with H₂O₂ prior to loading onto the resin has been demonstrated to allow quantitative recovery of total dissolved iron. Deferrioxamine and Rhodoturlic Acid, two commercially available siderophores were used to investigate the effect of strong Fe(III)-binding organic ligands on the ability to retain iron at different pH values. Acidification of seawater samples to pH 1.7 dissociates the iron complexed to these organic ligands, thereby allowing total dissolved iron and copper to be determined. Acidified samples from Monterey Bay were analyzed by a flow injection method coupled to ICP-SFMS detection using the NTA Superflow resin in the pre-concentration step. Results from this study show that when seawater samples are stored acidified (pH 1.7) over time, a portion of iron(III) is reduced to iron(II), thus necessitating the use of H₂O₂ to reoxidize the Fe(II) to Fe(III) prior to analysis. Total dissolved concentrations of iron and copper can be directly obtained on seawater samples at pH 1.7 with this method, eliminating the need to buffer the sample to a higher pH prior to column loading. This resin has the potential to be used in shipboard or in situ flow injection methods.     

FT-Raman,FT-IR,NMR structural characterization and antimicrobial activities of 1,6-bis(benzimidazol-2-yl)-3,4-dithiahexane ligand and its Hg(II) halide complexes

1,6-Bis(benzimidaz-2-yl)-3,4-dithiahexane ligand (L) and its mercury halide complexes were prepared and characterised. The elemental analysis, molecular conductivity, FT-Raman, FT-IR (mid, far), ¹H, ¹³C NMR and geometry optimization in MOPAC using MNDOd parameter on CACHE, prove the existence of neutral, mononuclear and the distorted tetrahedral [Hg(L)X₂] complexes. In all the three complexes, the ligand acts as a chelating bidentate, through two of the bridging sulphur atoms and together with the monodentate coordination of the two anionic halide ligands to the metal centre forming a possible 4-coordinate compounds. The antimicrobial activities of free ligand, its hydrochlorinated salt, mercury halides and the complexes are evaluated using disk diffusion method in dimethyl sulfoxide (DMSO) as well as the minimal inhibitory concentration (MIC) dilution method, against 10 bacteria. The obtained results from disk diffusion method are assessed in side-by-side comparison with those of Penicillin-g, Ampicillin, Cefotaxime, Vancomycin, Oflaxacin and Tetracyclin well-known antibacterial agents. The results from dilution procedure are compared with Gentamycin as antibacterial and Nystatin as antifungal. The antifungal activities are reported on five yeast cultures namely Candida albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii and Hanseniaspora guilliermondii, and the results are referenced with Nystatin, Ketaconazole and Clotrimazole, commercial antifungal agents. In most cases, the compounds show broad-spectrum (Gram⁺ & Gram⁻ bacteria) activities that are comparatively, slightly less active or equipotent to the antibiotic and antifungal agents in the comparison tests.     

Studies on chelates of selected pyrazylmethyl ketones

Summary Several pyrazylmethyl ketones have been investigated in regard to their potential analytical utility as chelating agents for metal ions. Proton dissociation constants of the ligands and metal chelate formation constants were calculated from potentiometric data using the method of Irving and Rossotti. Chelate formation constants obtained in this study allow comparisons to be made between pyrazylmethyl ketones and other chelating agents possessing similar structures. The potential analytical utility of the title compounds is discussed.

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Zusammenfassung Einige Pyrazylmethylketone wurden auf ihre Fähigkeit zur Chelatbildung mit Metallionen untersucht. Die Protonendissoziationskonstanten der Liganden und die Chelatbildungskonstanten wurden aus potentiometrischen Daten berechnet, die nach Irving und Rossotti ermittelt wurden. Die Chelatbildungs-konstanten der Pyrazylmethylketone wurden mit denen ähnlich strukturierter Chelatbildner verglichen. Die analytische Brauchbarkeit der untersuchten Ketone wurde diskutiert.

     

Hemilabile‐coordinated copper promoted amination of aryl halides with ammonia in aqueous ethylene glycol under atmosphere pressure

Direct amination of aryl iodides and bromides with ammonia under 1 atm pressure has been effected using in situ‐generated hemilabile coordinated copper(I) species from copper(I) halides or copper metal in aqueous ethylene glycol, producing primary aromatic amines in good yields. Ammonia pressure and water were found to accelerate the copper‐mediated reaction while strong chelating ligands showed a suppression effect. A rationale for the copper‐mediated amination of aryl halides with ammonia is given based on a double‐face role of chelating effect. Copyright © 2009 John Wiley & Sons, Ltd.     

Chelating Resins in Analytical Chemistry

Chelating resins, the polymeric complexing compounds, are specific and selective ion exchange resins. A chelating ion exchange resin consists essentially of two components, i.e. a chelating group and a polymeric matrix. The properties of both components affect the selectivity of the synthesized resin. Methods used to synthesize chelating resins are reviewed. The analytical and physical techniques used to characterize the dissociation constant, metal capacity and distribution coefficient of the newly synthesized resin as well as the coordination site, the composition and the formation constant of the metal-resin complexes are discussed. Chelating resins could be used in various forms. Some important features of the analytical application of chelating resins, including selective concentration and separation both in inorganic analysis and organic analysis are also discussed. The techniques by which sorption or separation with the help of chelating resins achieved can be static, dynamic, or chromatographic. After sorptive concentration or separation, the elements can be determined either directly in the sorbent phase, its decomposition residue, the eluent solution after desorption, or the effluent after the solution has been passed through the sorbent. Various objects such as natural waters, geological objects, industrial materials, foodstuffs, coal, fuel oil. shale oil, transuranium elements and biological materials could be analyzed with the help of chelating resins.     

On the Reaction of [(CO)3Fe(μ‐Me2NCO)2Fe(CO)2(NHMe2)] with Chelating Ligands — X‐Ray Structures of New Binuclear μ‐Carbamoyl Complexes

Reaction of the binuclear μ‐carbamoyl complex [(CO)₃Fe(μ‐Me₂NCO)₂Fe(CO)₂(HNMe₂)] ( 1 ) in toluene with the chelating ligands Ph₂PCH₂PPh₂ (dppm) and Ph₂PCH₂CH₂PPh₂ (dppe) gives different results. With dppm only the complex [(CO)₃Fe(μ‐Me₂NCO)₂Fe(CO)₂(dppm)] ( 3 ) with a dangling ligand is obtained under replacement of amine, whereas with dppe depending on the reaction conditions up to three compounds are found. A 1 : 1 mixture of the educts generates the related complex [(CO)₃Fe(μ‐Me₂NCO)₂Fe(CO)₂(dppe)] ( 4 ) together with the tetranuclear complex [{(CO)₃Fe(μ‐Me₂NCO)₂Fe(CO)₂}₂(dppe)] (5 ). 4 slowly converts into [(CO)₃Fe(μ‐Me₂NCO)₂Fe(CO)(dppe)] ( 6 ) with dppe acting as a chelating ligand. 6 is the first compound in this series in which one of the five CO groups is replaced by another donor. A 2 : 1 molar ratio of 1 and dppe quantitatively produces 5 . Addition of CO to a solution of 6 proceeds under slow reversible conversion of the complex into 4 . The compounds were characterized by the usual spectroscopic methods; 3 , 5 and 6 were also studied by X‐ray diffraction analyses.     

Synthesis of New Functionalized Organophosphorus Acids and their Derivatives

Abstract

Functionalized organophosphorus acids and their derivatives are of great interest as chelating ligands, bioactive substances with various properties and the key compounds for the synthesis of phosphorus containing peptides. We have developed the convenient methods of the synthesis of new functionalized organophosphorus acids and their derivatives using a series of PH-acids and their esters with highly reactive fragments PH and POSi as well as phosphorus containing arnines with fragments PCHNH and PCHNSi. These organophosphorus synthons react smoothly with α-heterosubstituted derivatives of various amines and amides, functionalized alkenes and their oxides, as well as with acyl and sulfonyl chlorides giving the perspective compounds with high yields. New available types of new functionalized organophosphorus acids and their derivatives are presented below.     

Hydrophile Polymergele mit reaktiven Gruppen, 3. Mitt.: Chelatharze mit Formazan-Ankergruppen auf Basis von Saccharosemethacrylaten

The preparation and properties of hydrophilic chelating resins containing formazans as functional groups are described. Sucrosemethacrylat-gels with primary aromatic amino groups were diazotised and coupled with various substituted phenylhydrazones yielding gels with formazans as chelating anchor groups. The capacities of the gels were max. 1,6 mmol/g. The recycle of adsorption and elution was found to be satisfactory for Co²⁺ and Pb²⁺ whereas only 60% of the bonded Hg^2– could be recovered reversibly.

     

钯等过渡金属催化的卤代芳烃和胺的偶联反应

综述了钯等过渡金属催化的卤代芳烃或芳基碘酸酯和胺的偶联反应以及催化这 一新反应的催化剂的发展和应用。用于该反应的配体由P（o-tolyl)3发展到BINAP 及二烷基芳基膦，基底物由溴代芳烃扩展到经济易得的氯化芳烃及碘酸酯和各种胺。     

Comparability of copper complexation capacity determination by absorption by chelating resin column and cathodic stripping voltammetry

A simple method has been developed for the determination of copper complexation capacity. It is based on absorption of non-complexed species on a chelating resin column. The limit of detection is for complexation equivalent to 3 μg Cu l⁻¹ and the relative standard deviation of results is 10%. The method has been shown to be of comparable performance with voltammetric techniques in respect of the ligands detected. The approach offers the possibility of use in the field and of application to the determination of the speciation of other divalent trace metals.     

Synthesis and characterization of 4-(alkylaminoisonitrosoacetyl)biphenyls and their complexes

Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhydroxymoyl chloride and corresponding amines were synthesized. The following aromatic and aliphatic amines were used for ligands: ethanolamine, 2-amino-4-methylphenol, and 2-(aminomethyl)pyridine. Mononuclear or binuclear cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and lead(II) complexes with these ligands were synthesized. These compounds were characterized by elemental analyses, AAS, infrared spectra, and magnetic susceptibility measurements. The ligands were additionally characterized by ¹H NMR. The results suggest that the ligands act as tridentate ligands. The text was submitted by the authors in English.     

Complexation of N-tris[(1,2-dicarboxyethoxy)ethyl]amine with Ca(II), Mn(II), Cu(II) and Zn(II) in aqueous solution

In a search for environmentally friendly metal chelating ligands for industrial applications, the protonation and complex formation equilibria of N-tris[(1,2-dicarboxyethoxy)ethyl]amine (TCA6) with Ca(II), Mn(II), Cu(II) and Zn(II) ions in aqueous 0.1?M NaCl solution were studied at 25°C by potentiometric titration. A model for complexation and stability constants of the complexes were determined. With all of the metals, complex formation was dominated by ML^4?. Comparison of TCA6 and six other chelating agents showed TCA6 to be suitable for applications where strong calcium binding is essential.