Redox reactions in non-aqueous media: determination of organic isothiocyanates alone, in formulations and in important mixtures

A simple potentiometric method for the determination of organoisothiocyanates is described. The isothiocyanate is treated in acetonitrile medium with an excess of primary amine to convert it into a substituted thiourea and the surplus amine is converted into a dithiocarbamate by addition of carbon disulphide. The solution is then titrated with a copper(II) solution in acetonitrile. The three-step titration curve enables the results to be calculated on the bash of the dithiocarbamate and/or thiourea formed. The method has been successfully applied to the analysis of a commercial insecticide formulation based on isothiocyanate and important mixtures containing isothiocyanates.     

Novel generation of 9H-furo[3,2-b]chromen-9-ones from （E）-3-hydroxy-2-styrylchromones by excited state intramolecular proton transfer

Photocyclisation of substituted （E）-3-hydroxy-2-（V-methyl-2＇-phenylvinyl）-4-oxo-4H-1-benzopyrans to yield linear novel tricyclic 9H-furo[3,2-b]chromen-9-ones and angular fused tetracyclic xanthenones is described.     

Evaluation of Ethylene Propylene Diene Terpolymer based insulation against Nitrile rubber based insulation for large Composite Rocket Motor Casing

Even though literature available on EPDM is abundant, the data on physical, mechanical, thermal, interface properties and ablative performance as specifically required for the design and acceptance of internal insulation of large Composite Rocket Motor Casing is scant in the plethora of literature available in the subject of EPDM insulation. This gave the impetus to take up this experimental work wherein most promising formulation of EPDM with Kevlar and silica as reinforcing fillers and with only silica as reinforcing filler were thoroughly characterized for the insulation requirements of large Composite Rocket Motor Casing and compared with the performance of proven Nitrile rubber based insulation. The significant findings which are unique, are discussed in this paper.     

Phototransformations of some 3‐cyclohexenyloxychromenones: Synthesis of Spirocyclic compounds

The phototransformation of the 3‐cyclohexenyloxychromenones by irradiation with a pyrex‐filtered light from a 125 W Hg vapor lamp under an inert atmosphere into the spirocyclic fused xanthenones was described. The efficacy of the protocol depended upon the position (o‐, m‐, or p‐) of the cyclohexenyloxy group appended to the 2‐aryl moiety on the chromenone nucleus, which was further invoked by steric, electronic, and proximity considerations. The structure(s) of the substrates and photoproducts were established using the spectroscopic (IR and NMR) data.     

Design and development of bioactive α-hydroxy carboxylate group modified MnFe2O4 nanoparticle: Comparative fluorescence study,magnetism and DNA nuclease activity

Three new α-hydroxy carboxylate group functionalized MnFe₂O₄ nanoparticles (NPs) have been developed to explore the microscopic origin of ligand modified fluorescence and magnetic properties of nearly monodispersed MnFe₂O₄ NPs. The surface functionalization has been carried out with three small organic ligands (tartrate, malate, and citrate) having different number of α-hydroxy carboxylate functional group along with steric effect. Detailed study unveils that α-hydroxy carboxylate moiety of the ligands plays key role to generate intrinsic fluorescence in functionalized MnFe₂O₄ NPs through the activation of ligand to metal charge transfer transitions, associated with ligand–Mn²⁺/Fe³⁺ interactions along with d–d transition corresponding to d–orbital energy level splitting of Fe³⁺ ions on NP surface. Further, MnFe₂O₄ NPs show a maximum 140.88% increase in coercivity and 97.95% decrease in magnetization compared to its bare one upon functionalization. The ligands that induce smallest crystal field splitting of d–orbital energy level of transition metal ions are found to result in strongest ferrimagnetic activation of the NPs. Finally, our developed tartrate functionalized MnFe₂O₄ (T-MnFe₂O₄) NPs have been utilized for studying DNA binding interaction and nuclease activity for stimulating their beneficial activities toward diverse biomedical applications. The spectroscopic measurements indicate that T-MnFe₂O₄ NPs bind calf thymus DNA by intercalative mode. The ability of T-MnFe₂O₄ NPs to induce DNA cleavage was studied by gel electrophoresis technique where the complex is found to promote the cleavage of pBR322 plasmid DNA from the super coiled form I to linear coiled form II and nicked coiled form III with good efficiency.     

Thermodynamic and lamella models relationship for the eutectic system benzoic acid – cinnamic acid

The present investigation reveals the relationship between excess thermodynamic functions and the growth habits of the eutectic phases from the melt by continuous melt‐growth technique. Excess thermodynamic functions computed for different compositions of the benzoic acid – cinnamic acid eutectic system have been found consistent with the criteria of spontaneity and Planck formulation, and their reliability has been ascertained by the application of Guggenheim lattice theory. The results on the kinetics of anisotropic growth of the eutectic phases from the melt, evidentially evince the dislocation mechanism. Evidences have been obtained for a parabolic variation of mechanical strength with growth velocity of the eutectic material grown anisotropically from the melt at different intervals, which offer supporting complement to the dislocation mechanism governing the dependence of growth velocity on supercooling ΔT in the solidus – liquidus interface in a form : V = k(ΔT)². A moderate anisotropic growth region has been explored by unique results of strength properties and microscopic results as well, to growing a layer of lamellae in a unidirectional lamina. An anisotropic eutectic composite lamellae lamina developed by moderate growth velocity (7.3 × 10^‐8m³s^‐1), is of greater interest offering optimum hardness, approximately varying between three‐and eight fold average increase in different modes of the mechanical strength in comparison to its isotropic growth carried out in an ice‐bath (∼273K), and manifold superior to its constituent phases irrespective of the growth mode. The directional lamina of uniform microstructural parameter lamellae, indicates that there is a perfect lamella‐ matrix equilibrium for which excess thermodynamic functions do vanish. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mössbauer study of the thermal decomposition of iron(III) citrate pentahydrate

The thermal decomposition of iron(III) citrate pentahydrate, Fe(C₆H₅O₇) · 5 H₂O, has been investigated at different temperatures in air using Mössbauer spectroscopy, nonisothermal techniques (DTA-TG) and X-ray diffraction. The reduction of iron(III) to iron(II) takes place at 553 K. At higher temperature the formation of -Fe₂O₃ and -Fe₂O₃ as the ultimate thermal decomposition products has been confirmed.

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Zusammenfassung Die thermische Zersetzung des Pentahydrates von Eisen(III)-citrat in Luft wurde bei verschiedenen Temperaturen durch Mössbauer-Spektroskopie, nicht-isotherme Techniken (DTA, TG) und Röntgendiffraktometrie untersucht. Die Reduktion von Eisen(III) zu Eisen(II) erfolgt bei 553 K. Bei höheren Temperaturen entstehen -Fe₂O₃ und -Fe₂O₃ als End-produkte der thermischen Zersetzung.

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(- ), - , (***) . 553 . , -F₂₃ -Fe₂O₃. .

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The authors are grateful to Dr. B. Mukherjee, C. G. C. R. Institute, Calcutta, for recording the X-ray diffraction pattern.     

Studies on 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)thiosemicarbazone complexes of some bivalent metal ions

Summary Complexes of 4-(2-thiazolyl)-1-(2,6-diacetylpyridine)-thiosemicarbazone, H₂C₃NSCNH(S)NHNCMeC₅H₃N-C(O)Me (Htdaptsc) of the compositions [M(Htdaptsc)₂Cl₂] [M=Mn^II, Co^II, Ni^II or Zn^II] [M(Htdaptsc)Cl₂] [M=Zn^II, Cd^II or Hg^II] and [M(tdaptsc)₂] [M=Mn^II, Co^II, Ni^II, Cu^II, or Zn^II] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, e.s.r. and i.r. studies, and their stereochemistries are discussed.     

Studies on complexes of 4-(2-thiazolyl)thiosemicarbazide with some bivalent metal ions

Summary The 4-(2-thiazolyl)thiosemicarbazide HTTSC, reacts with metal ions to yield two types of complex M(HTTSC)₂ Cl₂ [M=cobalt(II), nickel(II) copper(II), cadmium(II), or mercury(II)] and [M(TTSC)₂] [M=cobalt(II), nickel(II) or copper(II)]. These complexes have been characterized by elemental analyses and studied by magnetic and spectroscopic techniques. Tetrahedral coordination around cadmium(II) and mercury(II), square planar geometry around cobalt(II) and nickel(II) in [Co(TTSC)₂] and [Ni(HTTSC)₂]Cl₂, respectively, and octahedral stereochemistry for the remaining complexes is proposed.