Mössbauer study on thermal decomposition of some hydroxy iron(III) carboxylates

Thermal decomposition of some hydroxy iron(III) carboxylates, i.e., iron(III) lactate, Fe(CH₃CHOHCOO)₃, iron(III) tartrate, Fe₂(C₄H₄O₆)₃ and iron(III) citrate, Fe(C₆H₅O₇) · 5H₂O has been studied in static air atmosphere in the temperature range 298–773 K employing Mössbauer, infrared spectroscopies and themogravimetric methods. The compounds directly decompose to -Fe₂O₃ without undergoing reduction to iron(II) intermediates. An increase in particle size of -Fe₂O₃ has been observed with increasing decomposition temperature. The thermal stability follows the sequence: iron(III) tartrate > iron(III)citrate > iron(III)lactate.     

Mild Organic Ammonium Tribromide–Mediated Regioselective Ring Opening of Epoxides with Alcohols,Water, Acetic Anhydride,and Amines Under Solvent-Free Reaction Conditions

Organic ammonium tribromide (OATB), N-methylpyrrolidine-2-one hydrotribromide (MPHT) was found to be an efficient catalyst for the regioselective ring opening of epoxides with various nucleophiles under solvent free conditions. This procedure occurs under neutral and mild reaction conditions with out adding any additive and afforded high yields of products.

Synthesis of 2,2′‐Bi‐2H‐3,3′‐diaryl‐1,4‐benzothiazines from α,α‐Dibromoacetophenones and o‐Aminothiophenol

Some 2,2′‐bi‐2H‐3,3′‐diaryl‐1,4‐benzothiazines (5a–f) were synthesized from α,α‐dibromoacetophenones and o‐aminothiophenol.     

Synthesis of ferrites: Thermal analysis of some transition metal tris(maleato)ferrates(III)

Thermal analysis of some transition metal ferrimaleate precursors, M₃[Fe(mal)₃]₂·xH₂O (M=Mn, Co, Ni, Cu) has been studied in static air atmosphere from ambient to 600°C. Various physico-chemical techniques, i.e. TG, DTG, DTA, XRD, IR, Mössbauer spectrometry, have been employed to characterize both the intermediates and final products. After dehydration the anhydrous precursors undergo decomposition to yield an iron(II) intermediate, M[Fe^II(mal)₂] (M=Mn, Co, Ni, Cu) in the temperature range 160-275°C. A subsequent oxidative decomposition of iron(II) species leads to the formation of -Fe₂O₃ and MO in the successive stages. Finally a solid-state reaction occurs between the oxides above 400°C resulting in the formation of transition metal ferrites, MFe₂O₄. The ferrites have been obtained at much lower temperature and in less time than in the conventional ceramic method.This revised version was published online in November 2005 with corrections to the Cover Date.     

Microbial synthesis of gold nanoparticles: Current status and future prospects

Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized.     

Physico-chemical studies on thermal analysis of cobalt hexa(formato)ferrate(III) decahydrate

Thermal decomposition of cobalt hexa(formato)ferrate(III) decahydrate, Co₃[Fe(HCOO)₆]₂. 10H₂O, has been studied up to 973 K in static air atmosphere, employing TG, DTG, DSC, XRD, ESR, Mössbauer and infrared spectroscopic techniques. Dehydration occurs in two stages in the temperature range of 340–430 K. Immediately after the removal of the last water molecule the anhydrous complex undergoes decomposition till -Fe₂O₃ and cobalt carbonate are formed at 588 K. In the final stage of remixing of cations, a solid state reaction between -Fe₂O₃ and cobalt carbonate leads to the formation of CoFe₂O₄ at a temperature (953 K) much lower than for the ceramic method. A saturation magnetization value of 2310 Gauss of ferrite (CoFe₂O₄) shows its potential to function at high frequencies.     

Hydroxy(tosyloxy)iodo]benzene mediated alpha-azidation of ketones

Reaction of various ketones with [hydroxy(tosyloxy)iodo]benzene (HTIB) followed by treatment of the alpha-tosyloxy ketones thus generated in situ with NaN3 offers a one-pot procedure for the synthesis of alpha-azido ketones. The HTIB used in this conversion may also be generated in situ by using iodosobenzene in combination with p-toluene-sulphonic acid.     

Synthesis,Electrochemical and Antimicrobial Studies of Me6-Dibenzotetraazamacrocyclic Complexes of Ni(II) and Cu(II) Metal Ions

Russian Journal of Electrochemistry - Me6-dibenzotetraaza[14] annulene type macrocyclic complexes of Ni(II) and Cu(II) have been synthesized by template method and characterized by employing...     

Physico-chemical Studies on Thermal Decomposition of Alkali Tris(maleato)ferrates(III)

The thermal decomposition of alkali tris(maleato)ferrates(III), M₃ [Fe(C₂ H₂ C₂ O₄ )₃ ] (M =Li, Na, K) has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, XRD, Mössbauer and IR spectroscopic techniques. The anhydrous complexes decompose in the temperature range 215–300°C to yield Fe(II)maleate as an intermediate followed by demixing of the cations forming α-Fe₂ O₃ and alkali metal maleate/oxalate in successive stages. In the final stage of remixing of the cations (430–550°C) a solid state reaction occurs between α-Fe₂ O₃ and alkali metal carbonate leading to the formation of fine particles of respective ferrites. The thermal stabilities of the complexes have been compared with that of alkali tris(oxalato)ferrates(III).     

Physico-chemical studies on the thermolysis of strontium and barium ferrimaleates

The thermolysis of strontium and barium tris(maleato)ferrates(III), M₃ [Fe(C₂ H₂ C₂ O₄ )₃ ]₂ ·x H₂ O has been investigated from ambient temperature to 800 °C using simultaneous TG-DTG-DTA, XRD, Mössbauer and IR spectroscopic techniques. After dehydration the anhydrous complexes undergo decomposition to yield an iron(II)maleate/oxalate intermediate in the temperature range of 240-280 °C. An oxidative decomposition of iron(II) species leads to the formation of -Fe₂ O₃ and respective alkaline earth metal carbonate in the successive stages. Finally at 540-590 °C, a solid state reaction occurs between -Fe₂ O₃ and strontium/barium carbonate resulting in the formation of SrFeO_2.5 and BaFe₂ O₄ , respectively.