NOPR Collection:

First example of a double stranded helicate with square-planar coordination for the metal

Mon, 01 Nov 1999 00:00:00 GMT

Title: First example of a double stranded helicate with square-planar coordination for the metal Authors: Zimmer, Marc; Tocher, Derek A; Patra, Goutam K; Naskar, Jnan P; Datta, Dipankar Abstract: Reaction of dichlorobis(benzildihydrazone)Ni(II) with biacetylmonoxime in 1:4 molar proportion generates diamagnetic Ni₂L₂ where LH₂ (H = dissociable oximato proton) is HO-N=C(CH₃)-C(CH₃)=N-N=C(C₆H₅)-C(C₆H₅)=N-N=C(CH₃)-C(CH₃)=N-OH. Our molecular mechanics calculations show that Ni₂L₂ is an unprecedented double stranded homotopic helicate with the metal ion having a square-planar N₄ coordination. Page(s): 1087-1091

Stereochemical, thermal and biochemical aspects of dioxomolybdenum(VI) and manganese(II) complexes

Mon, 01 Nov 1999 00:00:00 GMT

Title: Stereochemical, thermal and biochemical aspects of dioxomolybdenum(VI) and manganese(II) complexes Authors: Singh, Ran Vir; Gupta, Neeti; Fahmi, Nighat Abstract: Stereochemical, thermal and biochemical studies of molybdenum(VI) and manganese(II) complexes prepared by the reactions of dioxobis (2,4-pentanedionato) molybdenum(VI ) and hydrated manganese dichloride with 2-hydroxy-N-phenylbenzamide, 1-[2-hydroxy- pheny l)-l-N-phenyl amino]hydrazine carboxamide and 1-[2-hydroxyphenyl)- 1-N-phenylamino]hydrazine carbo-thioamide in different stoichiometries have been reported. An attempt has been made to establish the structures of the resulting complexes on the basis of elemental analysis, molecular weight determinations magnetic measurements, IR, ¹H and ¹³C NMR, UV and ESR spectral studies.The results of thermogravimetric and differential thermal analysis of the complexes suggest first order reaction. The X-ray powder diffraction pattern of representative compounds confirms the orthorhombic crystal system. The antimicrobial screening data of in vitro studies indicate that the metal chelates are more potent than the parent ligands. The in vivo studies of the representative ligands and their corresponding metal derivatives indicate them to be effective in cont rolling the leaf spot disease of brinjal plant caused by A.alternata. The antifertility screening data indicate the anti-androgenic nature of the complexes. Page(s): 1150-1158

Kinetics and mechanism of ruthenium (III) - catalysed oxidation of pyrimidine bases by peroxydiphosphate in aqueous perchloric acid medium

Mon, 01 Nov 1999 00:00:00 GMT

Title: Kinetics and mechanism of ruthenium (III) - catalysed oxidation of pyrimidine bases by peroxydiphosphate in aqueous perchloric acid medium Authors: Latha, B Suvarna; Adinarayana, M; Rao, P Jayaprakash Abstract: Kinetics and mechanism of Ru(III) - catalysed oxidation of pyrimidine bases by peroxydiphosphate (PDP) have been studied in aqueous perchloric acid medium. The reaction is first order each in [PDP] and [Ru(III)] and the rate is independent of [substrate]. The reaction is insensitive towards changes in acid concentration while the effect of ionic strength is negligible on the rate of oxidation. The reactions have been studied at different temperatures and activation parameters evaluated. A mechanism, involving the two-electron oxidation of Ru(III) by PDP in a slow step, is proposed. Page(s): 1184-1187

Immobilization of -amylase on porous silica

Mon, 01 Nov 1999 00:00:00 GMT

Title: Immobilization of -amylase on porous silica Authors: Mody, H M; Mody, K H; Mairh, O P; Jasra, R V Abstract: Porous silica has been synthesized by hydrolysis of sodium silicate with ammonium chloride in the presence of sodium lauryl sulphate and the resultant gel hydrothermally treated. Surface of the silica, thus prepared, has been functionalized by silylati on using 3- aminopropyl triethoxysilane. This material has been used as a support for immobilization of -amylase. Starch hydrolyzing activity of immobilized enzyme remains unchanged even after 10 days, thereby showing that surface derivatised silica is a potential support for the immobilization of enzymes. Page(s): 1200-1202