Anilinopyridine–metal complexes for the selective chromogenic sensing of cyanide anion

Abstract

Probe 1, which contains an anilinopyridine chromophore and an aza-oxa macrocyclic subunit, presented an absorption band centered at 340 nm in acetonitrile. Addition of Fe(III), Cr(III) and Hg(II) induced the growth of a new absorption band at 430 nm (with color change from colorless to yellow), whereas in the presence of Cu(II), Zn(II) and Pb(II), less marked changes were observed. The color changes observed upon addition of Fe(III), Cr(III) and Hg(II) were ascribed to the formation of 1:1 stoichiometry complexes with probe 1. Coordination of Fe(III), Cr(III) and Hg(II) with the pyridine fragment of 1 induced an enhancement of the charge transfer character accompanied with a marked bathochromic shift that was reflected in a color change from colorless to yellow. The strength of the interaction between probe 1 and Fe(III) cation was modulated upon interaction with anions. Of all the anions tested, only cyanide was able to induce the bleaching of the yellow 1·Fe(III) complex solution. This bleaching was ascribed to the formation of 1·Fe(III)-CN complex that restored, to some extent, the optical features of the free probe allowing the chromogenic sensing of cyanide. Besides, 1·Fe(III) complex was used to detect cyanide in acetonitrile-water 90:10 v/v mixtures with good recoveries.     

Reactions of carbonate radical anion with amino-carboxylate complexes of manganese(II) and iron(III)

Abstract

The reaction kinetics of eight amino-carboxylate complexes of Fe(III) and Mn(II) with carbonate radical anion were studied using the pulse radiolysis method and UV-vis spectroscopy. Difference spectra revealed the formation of Fe(IV) and Mn(III) after reaction with CO₃^??. Spectral measurements revealed the first step to be the coordination of carbonate to the metal center. All of these led to the conclusion that the role of coordinated carbonate is essential to the electron transfer process by carbonate radical anion.     

Nicotinamide complex of silver(III) with expanded coordination number

Abstract

In strongly alkaline media ([OH^?]?≥?0.12 M), nicotinamide (nica) forms a complex with square-planar Ag(OH)₄^? [nica]?≥?0.05 M. The complex decomposes in seconds to nicotinamide N-oxide. The correlation of maximum absorbance of the complex with concentrations of nicotinamide and hydroxide requires that the complex is either the five-coordinate Ag(OH)₄(H_-1nica)^2? or the six-coordinate Ag(OH)₅(nica)^2?. Comparison with the reactions of Ag(OH)₄^? with nicotinate ion (nic^?) and acetamide under similar conditions indicates that nicotinamide coordinates with Ag(OH)₄^? by the amido group rather than the nitrogen on the pyridine ring or the amido oxygen. Kinetics of the Ag(III)-nica redox reaction are consistent with direct reaction between nicotinamide and uncoordinated Ag(OH₄)^?. Oxidation takes place at the pyridine ring, yielding nicotinamide N-oxide. Silver(III) is reduced to monovalent silver.     

Synthesis and Crystal Structure of Tris(N-p- methylphenyl-3-hydroxy- 2-ethyl-4-pyridinonato)iron(III)

1 INTRODUCTION A number of hydroxypyrones and hydroxypyridinones are being assessed or considered as orally effective chelators for treatment iron or aluminum overload[1,2]. Almost all present and potential applications involve the tris-ligand complexes of metal(III) cations, as for example in administration of iron(III) complexes for the treatment of anaemia[3], and the appropriate isotopes (e.g. 67Ga, 111In, 90Y) for radiotherapy or the isotopes of gadolinium for magnetic resonance …     

[Co(2,6-diaminomethylpyridine)(2-methylethylenediamine)Cl][ZnCl_4]体系中几何经式异构体的合成、结构解析和稳定性研究

合成了 [Co(bamp)(cmen)Cl]2＋ (bamp=2,6-二甲胺基吡啶; cmen=1,2-二胺基丙烷 )体系的两个经式异构体。利用一维及二维核磁共振 (2D NMR)技术,结合三元胺中吡啶环的磁屏蔽效应,对两个异构体在溶液中的结构进行了解析,对应于 Dowex 50Wx 2柱色层分离的第一色带的阳离子为 m2(cmen的 2位胺基与 Cl处于邻位 );第二色带的阳离子为 m1。由第一色带配合物制备的单晶晶体结构解析也表明其为 m2[ZnCl4]。用量子化学从头计算方法,在赝势基组 RHF/LANL2DZ的水平上研究了该体系两个经式几何异构体的稳定性,结果表明后者较前者稳定,但差别不大,与在合成条件下异构体平衡分布一致。由计算得到的几何优化键参数与晶体结构分析结果能较好地吻合。     

Determination of stability constants of some substituted 4-pyrazolone dyes containingo-methoxy,o-carboxy,ando-nitro groups with trivalent lanthanide ions

The relative stabilities of the metal derivatives of hydrazo pyrazolone dyes containingortho -OCH₃, -COOH, and -NO₂ groups have been measured potentiometrically in 75% (v/v) dioxane—water mixture at 30 °C and <0.1 ionic strength. The stability constant of their 1:1 and 1:2 chelates with twelve trivalent lanthanide ionsLn(III) have also been determined. The effects of substituents on the hydrazo-moiety of the ligand on the equilibria are discussed. The affinity of different ligands for complexation with lanthanide ions reaches its highest value withortho-carboxyphenylhydrazopyrazolone. The data were correlated and the results were used to explain the stabilization of such chelates by dative -bonding betweenLn(III) and the ligand.

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Bestimmung der Stabilitätskonstanten einigero-Methoxy-,o-Carboxy undo-Nitro-substituierter 4-Pyrazolon-Farbstoffe mit trivalenten Lanthanidenionen

Zusammenfassung Es wurden die relativen Stabilitäten der Metallderivate von Hydrazopyrazolon-Farbstoffen mitortho-OMe, -COOH und -NO₂ potentiometrisch in 75% (v/v) Dioxan—Wasser bei 30 °C und einer Ionenstärke <0.1 bestimmt. Die Stabilitätskonstanten der 1:1 und 1:2 Chelate mit zwölf trivalenten LanthanidenionenLn(III) wurden ebenfalls gemessen. Die Substituenteneffekte werden diskutiert. Dabei zeigeno-Carboxyphenylhydrazopyrazolone die höchste Affinität zu Lanthanidenionen. Die Daten werden miteinander korreliert und die Resultate auf der Basis einer dativen -Bindung zwischenLn(III)-Ion und dem Liganden diskutiert.

     

High-performance liquid chromatography using a color-forming agent as a mobile phase component. Separation of alkaline-earth-metal cations with arsenazo III and a non-porous gel column

Summary A liquid chromatographic procedure for separating alkaline-earth-metal cations with a non-porous gel column has been developed. Arsenazo III, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. Magnesium and calcium could be separated on the nonporous gel column within 55 seconds. The procedure was suitable for the separation of alkaline-earth-metal cations in relatively pure solutions with high sensitivity. Because of its rapidity the described procedure is also potentially applicable for any aqueous sample.     

Dye-ligand chromatography for the resolution and purification of restriction endonucleases

The resolution of restriction endonucleases from the same microorganism is conventionally achieved by lengthy fractionation protocols. We now report effective single-step procedures that exploit dye-ligand chromatography for the resolution and purification of restriction enzymes. After suitable initial screening, we demonstrated that resolution of two restriction activites can be achieved in one chromatographic step, and further purification can subsequently be effected using selected dye-adsorbents. Accordingly, we resolved in one step, Hpa I from Hpa II, Hind II from Hind III, and Sac I from Sac II. Furthermore, a three-step Chromatographic procedure has been developed to purify EcoRV suitable for commercial exploitation, as judged by the “overdigestion” and “cut-ligate-recut” quality control tests.     

Use of Different Salt Solutions in Salting-Out TLC of Co(III) Complexes on Silica Gel

Saturated aqueous solutions of 28 different salts have been studied as a potential mobile phases for salting-out thin-layer chromatography, on silica gel, of a series of four mixed bis-aminocarboxylato cobalt(III) complexes. In addition, by linear regression analysis of chromatographic data obtained for fifteen mixed aminocarboxylato Co(III) complexes (four series) with solutions of ammonium chloride, three alkali metal chlorides, and four alkaline earth metal chlorides, four linear dependences previously established on different adsorbents with (NH₄)₂SO₄ solutions were confirmed. The qualities of the separations achieved with the salts were compared and Li⁺, Mg²⁺, and Ca²⁺ chlorides are proposed as the most suitable.     

Validated thin‐layer chromatographic method for the identification and monitoring of the effect of the extraction method on the yield and phytochemical constituents of Egyptian Withania somnifera leaves

A sensitive, reliable, simple and rapid thin‐layer chromatographic method has been developed for routine analysis of withanolide S content for the purpose of quality control assessment of chemotype III of Withania somnifera. The new method was used first to compare the accumulation of withanolide S in different parts of the plant, which was found to be the highest in the leaves extract (0.21% w/w). Second, to investigate different extraction parameters that improve the extraction efficiency of withanolides from the leaves using conventional and ultrasound‐assisted extraction methods. The extraction efficiency was expressed via total withanolide content and withanolide S content.