Showing papers by "University of Rajasthan published in 1981"

Synthesis and characterization of some Alkoxide Derivatives of Copper(II)

Abstract: A number of alkoxides of copper(II), Cu(OR)2 (where R is a primary, secondary or tertiary alkyl group) have been synthesised by the reactions of anhydrous copper(II) chloride with lithium alkoxides in 1:2 molar and also by alcoholysis and trans-esterification techniques. All the derivatives have been characterized on the basis of various physico-chemical studies, viz., infra-red, electronic reflectance spectra and magnetic susceptibility measurements. Darstellung und Charakterisierung einiger Alkoxid-Derivate des Kupfer(II) Eine Reihe von Alkoxiden des Kupfer(II), Cu(OR)2, wurden dargestellt durch Reaktion von Kupfer(II)-chlorid mit LiOR im Molverhaltnis 1:2 sowie durch Alkoholyse und Umesterifizierung. Alle Derivate wurden charakterisiert durch verschiedene physikalisch-chemische Untersuchungen (IR, UV-VIS und magnetischen Messungen).

Synthesis, Analysis and Spectral Properties of Coordination Compounds of Silicon(IV) with Sulphur Donor Benzothiazolines

Abstract: Some interesting reactions of benzothiazolines derived from the condensation of 2,4-pentanedione, salicylaldehyde, 2-hydroxyacetophenone, 2-hydroxy-1-naphthaldehyde, glyoxal or diacetyl with 2-aminobenzenethiol and silicon tetra-acetate are reported. These ligands with as the donor systems, and represented by LH2 and L′H2, respectively, react with silicon tetraacetate to give monomeric Si(OAc)2(L), Si(L)2 and Si(OAc)2(L′) type of products. The acetoxy groups of the diacetoxy silicon Schiff base complexes have been found to undergo replacement reactions with 2-methylpentane-2,4-diol and the resulting compounds are hydrolytically stable. The infrared, electronic, and proton magnetic resonance spectra confirm the coordination of sulphur, nitrogen and oxygen to the silicon atom.

ELECTRONIC STRUCTURES OF SIMPLE AND BIMETALLIC ALKOXIDES OF LATER ‘3d’ TRANSITION ELEMENTS

Abstract: The alkoxo group (-OR) functions as a bridging ligand between similar as well as different metal atoms giving rise to coordination oligomers and bimetallic alkoxides respectively. The syntheses of a large number of simple alkoxides of Cr(III & IV), Mn(II), Fe(II & III), Co(II), Ni(II) and Cu(II) have been described. Most of these are non-volatile and insoluble in organic solvents, except chromium tetra-tertiary-butoxide, Cr(OBu t ) 4 and alkoxides of iron(III), Fe(OR) 3 , in general. These polymeric new alkoxides of later ‘3d’ metals differ from the alkoxides of earlier transition and main group elements in the comparatively much lesser lability of their alkoxy groups in general. The sharp differences in the alcoholysis reactions of these alkoxides with ramification of the alkyl group have been correlated with the changes in the stereochemistry of the alkoxide derivatives as revealed by physico-chemical studies. Further, a large number of monomeric volatile bimetallic isopropoxides of the above elements with aluminium, having the general formula, M[Al(OPr i ) 4 ] n , have been described for the first time. Structures of all these derivatives have been suggested on the basis of spectroscopic (visible, ultraviolet, infra-red and electron spin resonance) and magneto-chemical studies, with tetraalkoxy aluminate moieties functioning as univalent bidentate and in some cases as tridentate ligands.

Magnetic, Specthoscopic and X-Ray Wwder Diffraction Studies of Lanthanon (III) Complexes of Nitrogen and Sulanr Donor Ligands

Abstract: Ln(OPr1)(TYC), Ln2(TSC)3 and Ln(TSC)(TSCH) [where Ln = Pr(III) or Nd(III) and TSCH2 = bifunctional trident ate thiosemicarbazones e.g., H2N ; R1 = H, R2 = c6H4OH or C10H6OH and R1=CH3, R2-C6H4OH] type s of lanthnnan thiosemicarbazone derivatives have been ryntherized by 1:1, 2:3 and 1:2 (M:L) moler reectiona of tris (isopropoxy)lanthanon with thioremioarbazones derived by the condensation of salicylaldehyde, 2-hydroxy-l-naphthaldehyde or O-hydroxyacetophenone with thiosemioarbszide. There are obtained as coloulrd solids and behave as non-electrolytes in anhydrous IMF. Suitable struc structures based on elemental analysis, molecular weight detemlnations, conductance measurements and infrared and proton magnetic reaonanoe spectral studies together with magnetic mearurements are indicated for these compounds. The pyrolytic behaviour of a few derivatives has also been studied and the data have been used for evaluating the klnetic parameters along with thermal rtabilities. Further, the X-ray powder di...

Effect of ascorbic acid deficiency on the uptake of iodine by thyroid and non‐thyroid tissues of an air‐breathing freshwater fish Channa punctatus Bloch

Abstract: Using 131I as tracer, iodine uptake by various thyroid and non-thyroid tissues has been reported in Channa punctatus in which vitamin C deficiency was experimentally induced by feeding vitamin C deficient diet to a level when morphological deficiency syndromes appeared. This was compared with a parallel control, fed a complete diet. The study showed a highly significant decrease in iodine uptake by thyroid tissues in vitamin C deficient fish as compared to the controls. However, the blood and other non-thyroid tissues recorded a significant increase in absorption and distribution of iodine. These findings suggested hypofunctioning of thyroid gland due to a prolonged deficiency of vitamin C.

Mossbauer study of ferrite systems Co x Mn1−x Fe2O4 and Ni x Mn1−x Fe2O4

Abstract: Mossbauer spectra of Co x Mn1−x Fe2O4 and Ni x Mn1−x Fe2O4 ferrites withx values ranging from 0·1 to 0·8 in steps of 0·1 have been recorded at room temperature. All spectra exhibit well-defined Zeeman hyperfine patterns. It has been observed that hyperfine field at Fe3+ nucleus increases more rapidly by nickel substitution than by cobalt substitution. This has been explained in terms of exchange interactions and cation distribution in the spinels. Hyperfine fields, isomer shifts and quadrupole splittings have been determined.

Limnological study of a freshwater reservoir, Jamwa Ramgarh (Jaipur)

Abstract: Jamwa Ramgarh reservoir near Jaipur (Rajasthan) is one of the oldest man-made lakes in western India. This paper presents a case study of likely impacts of human activities in freshwater bodies. The history, vegetation and human activities in the catchment area, flora and fauna, physico-chemical characteristics and production in the reservoir are briefly described. The impact of increasing human activities in the last few years is discussed.

Synthesis and Properties of Titanium(IV) and Zirconium(IV) Complexes of Sulphur Containing Bibasic Tridentate Schiff Bases Having the Donor System

Abstract: Some sulphur bonded new S-(methyl or benzyl)-β-N-(2-hydroxy phenyl)methylenedithiocarbazate complexes of titanium(IV) and zirconium(IV) have been synthesized and characterized. Their probable structures have been suggested based on conductance measurements, molecular weight determinations and infrared, proton magnetic resonance and electronic spectral studies. The thermograms of bis [S-methyl-β-N-(2-hydroxyphenyl)methylenedithiocarbazato] titanium(IV) and bis [S-methyl-β-N-(2-hydroxyphenyl) methylenedithiocarbazato] zirconium(IV) have also been recorded and discussed.

Electrolytic reduction of vanillin to vanillyl alcohol at amalgamated copper, lead and zinc electrodes

Abstract: The electrolytic reduction of vanillin to vanillyl alcohol was investigated as a function of temperature, pH and current density at a stationary amalgamated copper cathode. The results were compared with those for amalgamated lead and zinc electrodes.

Lattice sum calculations and a Mössbauer study on electric field gradient in phlogopite

Abstract: Lattice sum contributions have been calculated at the two octahedral sites in a phlogopite mica assuming a systematic distribution of octahedral cationic charges. This, unlike the case of a random distribution of charges, is able to reproduce broad features of quadrupole doublet spectra in Mossbauer experiments suggesting that the doublet assignments in terms of the two structural sites,M 1 (trans) andM 2(cis), are quite valid. Angle dependence of Mossbauer spectra has also been studied for a ferric-rich phlogopite mica sheet to determine the orientation of the EFG principal axis component and the sign of the quadrupole coupling constant. Quadrupole splitting values and the positive sign of coupling constants match the theoretical predictions quite well but the model fails to predict the observed EFG orientation.

Triterpene Quinone-Methides from Gymnosporia montana

Abstract: Iguesterin, pristimerin, tingenone, beta-amyrin, beta-sitosterol and maytenonic acid have been isolated from the light petroleum extract of the stem bark and iguesterin, pristimerin, tingenone, beta-amyrin and beta-sitosterol from the root bark of Gymnosporia montana.

Pressure dependence of superconductivity in non-transition metals

Abstract: An expression for the volume dependence of electron-phonon coupling strength is derived by considering the corresponding variation of Fermi momentum explicitly. Numerical data for the critical volumes deduced from the formulation compare fairly well with the existing theories. The calculated values of logarithmic volume derivative of effective interaction strength are in good accord with experiments. The volume dependence of superconducting transition temperature evaluated for three representative cases of weak, medium, and strong coupling superconductors leads to the conclusion that the theory reproduces the experimental data satisfactorily. Ein Ausdruck fur die Volumenabhangigkeit der Elektron-Phonon-Kopplungsstarke wird bei expliziter Berucksichtigung der entsprechenden Anderung des Fermiimpulses abgeleitet. Numerische Werte fur die kritischen Volumina, die aus diesen Formeln abgeleitet werden, stimmen gut mit vorhandenen Theorien uberein. Die berechneten Werte der logarithmischen Volumenableitung der effektiven Wechselwirkungsstarke sind in guter Ubereinstimmung mit den Experimenten. Die Volumenabhangigkeit der Supraleitungsubergangstemperatur, die fur die drei reprasentativen Falle der schwachen, mittleren und starken Kopplungssupraleiter berechnet wird, fuhrt zum Schlus, das die Theorie die experimentellen Werte befriedigend reproduziert.

Effect of 2-mercaptopropionylglycine (MPG) on thyroid function in sub-lethally irradiated mice

Abstract: External irradiation resulted in an increase in thyroid131I uptake and plasma PB131I conversion ratio, whereas pretreatment with MPG reduced both the values significantly. Metabolic inhibition is suggested as a possible mechanism of action by the drug.

Weight changes in mice after intrauterine treatment with MPG (2-mercaptopropionylglycine) against I131 irradiation.

Abstract: MPG, administered in utero against I131-irradiation, protected young mice to some extent from loss of body weight at different postnatal intervals. Increase in the tissue weight induced by the internal emitter was enhanced at 6 weeks of age by the drug.