Physical,chemical and biological studies on transition metal complexes of chelating tridentate ligand

Summary The interaction of 1-benzoin-4-phenylthiosemicarbazone (H₂ BPS) with some transition metal ions has been investigated. The ligand can function as a tridentate chelating agent, giving M(HBPS)₂ and M(BPS). Potentiometric studies proved that the mechanism of chelation is based on hydrogen ion liberation. Spectral studies in solution show that the ligand could be used for the microdetermination of Cu^IIions. On the basis of magnetic and spectral data, an octahedral structure is proposed for the Co^II and Ni^II complexes and a square-planar structure for the Cu^II complex. The corrosion inhibition of aluminium in Cl₃CCO₂H using H₂BPS is studied. The electrical conductivity of H₂BPS and of its complexes have been measured. The ligand shows an activation energy in the range of semiconducting materials. The antimicrobial activity of all compounds has also been demonstrated.     

Extraction of tungsten and rhenium by basic or neutral extractants in xylene from mineral acidic media

Extraction of WO ₄ ^2– and ReO ₄ ^– by Adogen-381, tricaprylmethylammonium chloride, Hyamine 10-X, trioctylphosphine oxide or dibenzylsulphoxide in xylene from HNO₃, HCl or H₂SO₄ acid medium was investigated. Based on the separation factors obtained, the separation of ReO ₄ ^– from WO ₄ ^2– was elucidated. ReO ₄ ^– was separated from WO ₄ ^2– in high radiochemical purity: >99.9% by three successive extractions and strippings using Adogen-381 from HCl or HNO₃ acid medium.     

Synthesis of new triphenodithiazine- and indolocarbazolediones of biological interest

Tetrabromo-p-benzoquinone reacted with excess aromatic amines to give 2,5-dirylamino-3,6-dibromo-p-benzoquinones. The latter molecules on heating with sodium sulfide in alcohol in the presence of air gave triphenodithiazinediones. Heating with copper powder in nitrobenzene transformed these compounds into the respective indolocarbazolediones. Comparative antimicrobial and antifungal activities of the studied compounds were determined and discussed.     

Die Oxydationswirkung von Natrium-1,2-naphthochinon-4-sulfonat

Zusammenfassung Die Reaktionen von Natrium-1,2-naphthochino-4-sulfonat mit -Aminosäuren, primären aliphatischen Aminen, Dicarbonsäuren, aliphatischen -Hydroxysäuren und primären Alkoholen werden beschrieben. In allen diesen Fällen reagiert Natrium-1,2-naphtochinon-4-sulfonat als Oxydationsmittel und wird zu dem entsprechenden Diphenol reduziert.     

Allylsilane‐Modified Amino Acids from the Claisen Rearrangement

The Claisen rearrangement of the N‐protected, silylated allyl glycinates 11 and 12 led to the formation of allyl/silyl‐functionalized amino acids 13 and 14 in yields up to 80%. The diastereoisomer ratio varied from 2 : 1 to 29 : 1 for 11mb , and from 2 : 1 to 46 : 1 (syn/anti) for 12mb , depending on reaction conditions, as shown by X‐ray crystallographic analysis of 14mb . The relationship between the size of the alkyl groups on the chlorosilane reagent (Me₂R″SiCl, R″=Cl, Me, t‐Bu, Ph) used as an enolate trap and the observed stereoselectivity was investigated in the case of the Ireland–Claisen variant. Me₃SiCl gave the best results. However, the size of the alkyl groups on the silylated ester (Me₂R″Si, R=Me, t‐Bu, Ph, i‐Pr) did not exert a significant effect on the diastereoselectivity or yield of the rearrangement.     

Back titration with mercuric ntrate in alkaline medium; potentiometric estimation of aluminium and manganese

Summary Mercuric nitrate has been successfully used for back titrating excess EDTA amounts than required for chelation with Al³⁺ or Mn²⁺ ions. This principle was the basis underlying the potentiometric determination of small amounts of both metals in the range of 10 g to 6 mg. End points are attended within 0.01 to 0.02 ml of titrant with fair accuracy and reasonable jumps ranging from 35 to 88 mv per 0.1 ml of titrant.     

Applications involving oxidation with KBrO3: III. Rapid potentiometric methods for vanadium alone or in mixtures

A rapid and reliable method is given for the determination of vanadium based on oxidation of the V(IV) with a known excess of bromate to V(V). The unreacted oxidant as well as V(V) are subsequently reduced with sulfurous acid to V(IV). The resulting Br^?1 was potentiometrically titrated with Hg(I) using silver amalgam as the indicator electrode. The method finds application to the analysis of some binary and ternary mixtures.     

Potentiometric Membrane Sensor for Determination of Saccharin

A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described. It is based on the use of Aliquat 336S-saccharinateion-pair as an electroactive material in plasticized PVC membranes with o-nitrophenyloctylether or dioctylphthalate. The sensor is conditioned for at least two days in 0.1 mol L⁻¹ sodium saccharinate before use. It exhibits fast, stable and Nernstian response for saccharinate ions over the concentration range of 1.0 × 10⁻¹–5.0 × 10⁻⁵ mol L⁻¹ and pH range of 4.5–11. The sensor is used for determination of saccharin in some dosage forms. Results with an average recovery of 101% and a mean standard deviation of 0.2% are obtained which is compared favourably with data obtained using the British pharmacopoeia method. The sensor shows reasonable selectivity towards saccharin in presence of many anions and natural sweeteners.     

Non-covalent assemblies of negatively charged boronated porphyrins with different cationic moieties

A unique approach to non-covalent electron and energy transfer is described that is based on the formation of salt bridges between oppositely charged porphyrin units. A new class of electrostatically linked dimeric and pentameric porphyrins was synthesized by interaction of novel anionic boron containing porphyrins such as 5-(benzamidodecahydro-closo-dodecaborate)-10,15,20-triphenylporphyrin (N1) and meso-tetrakis-benzamidodecahydro-closo-dodecaborate)porphyrin (N2) and a variety of cationic meso-tetraarylporphyrin units. A bipyridine linked dimer (N1 · bpy · N1) was also prepared by employing N,N′-dimethyl-4,4′-bipyridinium (bpy) as a spacer between two mono-anionic species. A quinone-porphyrin dyad was also prepared for electron or energy transfer demonstration. All the synthesized assemblies were characterized by NMR, IR, UV-Vis, and mass spectroscopy. Significant spectral changes occurred in the absorption spectra of these non-covalent porphyrin assemblies compared to those of the reference monomers, indicating the presence of electronic interaction between the adjacent porphyrin units. Resonance light scattering was also used to study the formation of these assemblies in solution.     

Enaminones in heterocyclic synthesis: Synthesis and chemical reactivity of 3‐anilino‐1‐substituted‐2‐propene‐1‐ one

The 3‐anilinoenones 3a,b were prepared from the corresponding 3‐dimemyl‐aminopropenones. The reactivity of 3a,b towards a variety of carbon and nitrogen nucleophiles as well as naphthoquinones is reported.