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Indian Journal of Chemistry

Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical

 

 

 

VOLUME 42A

NUMBER 11

NOVEMBER 2003

 

CONTENTS

Rapid Communications

 2677

 A reactive vanadium catecholate with variable solid state coordination number

 

 

 

 

 

 

 Bharat Baruah & Animesh Chakravorty*

 

 

 2680

 First mononuclear and binuclear vanadate esters of mixed aliphatic-aromatic diols

 

 

 

 

 

Bharat Baruah, Kajal Krishna Rajak & Animesh Chakravorty*

 

 

Advances in Contemporary Research

 2683

Acid-base equilibria of hydroxamic acids: Spectroscopic investigation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 Kallol K Ghosh

 

 

 

Papers

 2698

Angle of graph energy - A spectral measure of resemblance of isomeric molecules

 

  Ivan Gutman* & Lemi Tűrker

 

 

The angle q of the energy of a graph is shown to satisfy the relation cos q = X Y. The term X depends on the size of the molecule whereas the term Y depends on a size-independent parameter a, 0 < a << 1.

 

 2702

 High performance polymer films : Part 6,

Durability behaviour – Effect of electron affinity and ionization potential of monomers on hydrolytic stability of polymide films

 

 

 

Shankar C Khatua & Sukumar Maiti *

 

 

 Durability behaviour of the polyimide/copolyimide films based on pyromellitic dianhydride and 3,3′, 4,4′ – benzo- phenonetetracarboxylic dianhydride and 4,4′-oxydianiline and a proprietary aromatic diamine has been studied in water, organic solvents and oils, acids and alkalies etc., with the Kapton H film of Du Pont, USA as the reference. A polymide film based on a dianhydride of lower Ea and a diamine of lower IP will be more stable hydrolytically than one based on a dianhydride and diamine of higher Ea and IP values

2708

 

 Viscosity of 1-propanol + ethylene glycol dimethyl, + diethylene glycol dimethyl, + tri- ethylene glycol dimethyl, and + tetraethylene glycol dimethyl ethers at 288.15, 298.15 and 308.15 K

 

Amalendu Pal* & Anil Kumar

 

 

 The viscosity in binary liquid mixtures of 1-propanol with ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether have been measured as a function of mole fraction at 288.15, 298.15 and 308.15 K. The results are discussed in terms of interactions between the components of the mixtures.

 2717

 Synthesis and characterization of AlPO4-5 from aqueous and non-aqueous systems using hexamethyleneimine template

 

 

 

 

N Venkatathri

 

 

 

 2721

 Stability, energetics and DNA binding studies of zinc complexes

 

 P Rabindra Reddy, M Radhika  &  S Krishna Mohan

 

 

 

 2727

 Extraction studies and synthesis of molybdenum(VI) complexes of 4-adipoyl and 4-sebacoyl derivatives of bis(1-phenyl-3-methyl-pyrazolone-5)

 

 

 

B Augustus Uzoukwu* & Karsten Gloe

 

 

 

 2735

 Synthesis, spectroscopic and X-ray structure characterization of ethylenediammonium chromate and ethylenediammonium dichromate

 

 

 

 

 

B R Srinivasan*, Sunder N Dhuri, Christian Näther & Wolfgang Bensch*

 

 

 

Notes

2742

Effect of g-irradiation on the thermal decomposition of MgC2O4 and TiO2 mixture

 

 

 

 

 

S C Moharana, J Praharaj, S Pati & D Bhatta*

 

 

 Simultaneous rising temperature technique and gas evolution method have been adopted for studying the thermal decomposition of unirradiated and irradiated MgC2O4 and Mg C2O4 + TiO2 mixtures. The decomposition follows Avrami – Erofeev mechanism (n=2), unaltered in the mixture and irradiated salts, suggesting that nucleation and growth process occurs at the reactant product interface, in two dimensional chain branching manner.

 2746

Studies on quenching/antiquenching effect of some organic compounds on luminescence of CdS colloids

 

 

 

O P Yadav* & Praveen Kumar Sansanwal

 

 

Effect of some amines and phenol on luminescence intensity of CdS colloids has been studied. The additives with electron donors groups (-NH2 or -OH) bind to lower energy trap sites which are involved in nonradiative decay, causing enhanced fluorescence

2749

 Study of CMC value of binary mixtures of surfactants

 

 

H D Joshi, Komal H Joshi, Geetaben C Desai & C M Desai*

 

 

 The mixtures of cetyl pyridinium bromide and cetramide, are studied spectroscopically using eosin dye. The CMC value of the mixtures have been determined by measuring absorbance intensity at lmax of the solution.

 

 2751

 Reaction of cis-diaqua nitrilotriacetato-chromate(III) with L-ascorbic acid: A kinetic study

 

 

 

 

Gouri S Brahma, P Mohanty* & B Nanda

 

 

2757

 Investigation of the crystallization kinetics of Zn(Phe)SO4 · H2O by microcalorimetry

 

 

 

G Shengli*, F Yan, C Sanping, H Rongzu & S Qizhen

 

 

 The crystal growth process of Zn(Phe)SO4 · H2O from water and acetone has been investigated using a Calvet microcalorimeter. The heat produced and the rate of heat production during the crystal growth process at 293.15 K, 295.15, 298.15 and 300.15 K have been measured. The results show that the crystal growth proceeds in accordance with the Burton-Cabrera-Frank dislocation theory.

2762

Synthesis, characterization and thermal studies of some new organotin (IV) complexes with aniline N-thiohydrazide and benzaldehyde aniline N-thiohydrazone

 

N K Kaushik* & A K Mishra

 

 

 

2767

 Synthesis, characterization and biological properties of N-nicotinoyl-N´-thiobenzoyl-hydrazine complexes of cobalt (II), nickel (II), copper (II) and zinc (II)

 

 

N K Singh*, S B Singh, D K Singh & V B Chauhan

 

 

 

2772

Synthesis, characterisation and redox behaviour of mixed ligand complexes of osmium(II/III/IV)

 

 

 

Habibar Chowdhury, Doyel Bose, S K Hafijur Rahaman & Barindra Kumar Ghosh*

 

 

A group of mixed-tris chelates of osmium(II), -(III) and –(IV) of the general formula [OsL¢L2]z+ [L¢ = N-((pyridin-2-yl)formylidene)aniline or N-((pyridin-2-yl) benzylidene) aniline; L = 2,2¢-bipyridyl, 2-(m-tolylazo)pyridine or quinolin-8-olate; z = 1–3] have been prepared, isolated as their perchlorates and characterized.

 2778

Oxovanadium(IV) and dioxouranium(VI) complexes of some acyclic monoterpenic constituents of essential oil

 

 Premlata Sharma, Mangal Chand & Meena Nagar*

 

 

2781

 Molecular complexes of paraquat with sodium purinates

 

 

 

 

G Anjaiah, T Veeraiah & G Venkateshwarlu*

 

 

 

 2784

Inhibitive effect of PEG on the corrosion of aluminium in acidic medium

 

  

Jyotsna Shukla, K S Pitre* & Praveen Jain

 

 

The mechanism of corrosion of aluminium and the effect of polyethylene glycol (PEG) polymer as corrosion inhibitor in acidic medium has been studied using the weight loss method, potentiodynamic and galvanostatic polarization measurements. The corrosion inhibition efficiency of PEG is 94% after 24 h.

2788

The effect of counterion and hydrogen ion concentrations on the capacity factor of weak monoprotic organic acids in ion‑pair reversed phase chromatography

 

 

 

Welford‑Abbey Lolo Izonfuo * & Happy John Timinebi Eke

 

 The weak monoprotic organic acids, benzoic and salicylic acids, have been ion‑paired with varying concentrations of tetrabutylammonium ion and retained in a reversed phase liquid chromatographic column. The capacity factor of both acids is found to be directly proportional to the concentration of the ion‑pairing reagent until the ion‑pair is quantitatively and completely formed.

Book Review

2792

 Liquid membrane phenomena: Biological implications

 

Kehar Singh

 

 

 

 

Authors for correspondence are indicated by (*)

 

Indian Journal of Chemistry

Vol. 42A, November 2003, pp. 2677-2679

 

A reactive vanadium catecholate with variable solid state coordination number

Bharat Baruah  & Animesh Chakravorty *

 

The title ester is VO(PriL)(Cl4Hcat) where PriL2- is the diionized salicylaldimine of L-valine and Cl4Hcat is monoioinzed tetrachlorocatechol. In the crystalline state it incorporates both octahedral and square pyramidal coordination geometries and in solution it undergoes a slow catecholase reaction.

 

 

 

Indian Journal of Chemistry

Vol. 42A, November 2003, pp. 2680-2682

 

 

First mononuclear and binuclear vanadate esters of
mixed aliphatic-aromatic diols

Bharat Baruah,  Kajal Krishna Rajak & Animesh Chakravorty*

 

The title esters [VO(gsal)(HL1)] and [{VO(gsal)}2(H2L2)] incorporate chelation by ionized 2-hydroxybenzyl alcohol (H2L1), its dimer-like derivative (H4L2) and the salicylaldimine of glycine (H2gsal). The phenolic functions of H2L1 and H4L2 are ionized in ester formation. The structure and spectral features of the esters are reported.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2683-2697

 

Acid-base equilibria of hydroxamic acids: Spectroscopic investigation

Kallol K Ghosh

 

This work reviews the acid-base equilibria of hydroxamic acids. Hydroxamic acids and metal hydroxamates have recently enjoyed an enormous expansion boosted by new discoveries on their high applicability in the cardiovascular diseases, HIV, malaria, cancer, metal poisoning and Alzheimer's disease. Unfortunately the basic structural chemistry of hydroxamic acids still unresolved problems. Although there are various spectroscopic (NMR, IR, FT-ICR-CID, Raman UV) and theoretical methods available for the study of acid-base behaviour, UV method is rapid, simple and reliable. In this review recent advances on acid-base behaviour has been discussed. Evaluation of the relative basicities and protonation parameters of polyfunctional acids and bases is an important task that has attracted much interest both as a source of information on the molecular electronic structure and as a tool to interpret the reactivity of acid-base catalysed reactions.

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2698-2701

 

Angle of graph energy—A spectral measure of resemblance
of isomeric molecules

Ivan Gutman*

 

A method, elaborated earlier by one of the present authors, for measuring the structural resemblance of isomeric alternant conjugated hydrocarbons, based on a graph-spectral quantity q, called the angle of total p-electron energy approach has been extended now to arbitrary molecules. Some general properties of q have been established.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2702-2707

 

High performance polymer films: Part 6, Durability behaviour – Effect of electron affinity and ionization potential of monomers on hydrolytic stability of polymide films

Shankar C Khatua & Sukumar Maiti*

 

Durability behaviour of the polyimide/copolyimide films based on two dianhydrides, pyromellitic dianhydride (PMDA) and 3,3¢, 4,4¢ – benzophenonetetracarboxylic dianhydride (BTDA) and two diamines, 4,4¢-oxydianiline (ODA) and a proprietary aromatic diamine (P1) has been studied in water, organic solvents and oils, acids and alkalies etc. with the Kapton H film of Du Pont, USA as the reference. The weight gain of the films after immersion in water for 5 days is in the range 0.12 to 81%. Hydrolytic stability of the Kapton H film in both concentrated and dilute aq. alkali solutions is very poor compared to most of the films under investigation. Its stability in concentrated H2SO4 (98% w/w) is also poor. Hydrolytic stability of any polymide or copolyimide can be predicted by electron affinity-ionization potential (Ea-IP) concept. A polymide film based on a dianhydride of lower Ea and a diamine of lower IP will be more stable hydrolytically than one based on a dianhydride and diamine of higher Ea and IP values. g-Ray irradiated films are practically unaffected in all respect viz. colour; toughness, flexibility etc. after a maximum dose of 21.60 Mrad which is below the critical dose level of g-irradiation.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2708-2716

 

Viscosity of 1-propanol + ethylene glycol dimethyl,
+ diethylene glycol dimethyl, + triethylene glycol dimethyl,
and + tetraethylene glycol dimethyl ethers at
288.15, 298.15 and 308.15 K

Amalendu Pal* & Anil Kumar

 

The viscosity (h) in binary liquid mixtures of 1-propanol with ethylene glycol dimethyl ether (1,2-dimethoxyethane), CH3OCH2CH2OCH3, diethylene glycol dimethyl ether [bis(2-methoxyethyl)ether], CH3OCH2CH2OCH2CH2OCH3, triethylene glycol dimethyl ether [1,2-bis(2-methoxyethoxy)ethane], CH3OCH2(CH2OCH2)2CH2OCH3, and tetraethylene glycol dimethyl ether (2,5,8,11,14-pentaoxapentadecane), CH3OCH2(CH2OCH2)3CH2OCH3, have been measured as a function of mole fraction at 288.15, 298.15, and 308.15 K. The values of the quantity Dh, which refer to the deviations of the experimental values of the dynamic viscosities of the mixtures from the mole fraction mixture law values, have been found to be negative for all the mixtures. Further, the excess free energies of activation of viscous flow (DG*E), have been calculated from the experimental data. The results for h, Dh and DG*E are discussed in terms of interactions between the components of the mixtures. Furthermore, activation enthalpies (DH*E), and enthalpies of viscous flow (DS*E) have been evaluated and their variation with concentration is discussed.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2717-2720

 

 

 

Synthesis and characterization of AlPO4-5 from aqueous and non-aqueous systems using hexamethyleneimine template

N Venkatathri

AlPO4-5 have been synthesized from aqueous and non-aqueous media using hexamethyleneimine template and characterized by XRD, SEM, carbon and nitrogen analysis, TG/DTA, FT-IR, 27Al and 31P MAS NMR. The results show that the samples are highly crystalline. Non-aqueous media synthesized samples are more crystalline compared to aqueous media samples. The presence of octahedral sites in 27Al MAS NMR is different from aqueous media synthesized samples.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2721-2726  

 

Stability, energetics and DNA binding studies of zinc complexes  

P Rabindra Reddy*, M Radhika & S Krishna Mohan

 

Interaction of zinc with peptides has been investigated and the stabilities as well as the energetics of the above system assessed. The binding modes and the geometry have been assigned by 1H and 13C- NMR spectroscopy and by potentiometric pH titrations. The investigations have been extended to DNA recognition studies to examine whether the small molecule model interacts with DNA or not. The results suggest that the model indeed recognizes DNA.

 

 

 

Indian Journal of Chemistry

 Vol. 42A, November 2003, pp. 2727-2734

 

Extraction studies and synthesis of molybdenum(VI)
complexes of 4-adipoyl and 4-sebacoyl derivatives of
bis(1-phenyl-3-methyl-pyrazolone-5)

B Augustus Uzoukwu* & Karsten Gloe

 

The liquid-liquid extraction of Mo(VI) with 4-adipoylbis(1-phenyl-3-methyl-pyrazolone-5) (H2AdP) and 4-sebacoylbis(1-phenyl-3-methyl-pyrazolone-5) (H2SP) has been studied in the presence and absence of decanol (DOH). The extracted species in the absence of DOH have been determined by slope analysis to be MoO2(AdP) and MoO2(SP). Addition of DOH in the organic phase results in increased extraction of Mo(VI) into the organic phase and the isolation of the adducts, MoO2(HAdP)2.DOH and MoO2(SP).DOH. The ion-pair complex species extracted from concentrated HCl solutions have been identified as MoO2(AdP)(DOH2+)2.2Cl- and MoO2(SP)(DOH2+)4.4Cl-. The extraction constants Kex, distribution constant KD and pH1/2 for the various extraction systems have been determined. IR spectral analysis show that O=Mo=O species exists as the cis-form in the complexes. The structures suggested by molecular modelling calculations for the ligands are presented.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2735-2741

 

Synthesis, spectroscopic and X-ray structure
characterization of ethylenediammonium chromate and ethylenediammonium dichromate

B R Srinivasan*, Sunder N Dhuri, Christian Näther & Wolfgang Bensch*

 

The reaction of ethylenediammonium chloride (enH2)Cl2 with potassium chromate or dichromate in a 1:1 mole ratio results in the formation of the title complexes ethylenediammonium chromate (enH2)[CrO4] 1 and ethylenediammonium dichromate (enH2)[Cr2O7] 2 in good yields. The two complexes have been characterized by IR, UV-Vis, 1H NMR spectroscopy and metal analysis and their structures have been determined by single crystal X-ray crystallography. Ethylenediammonium chromate 1 crystallizes in the orthorhombic space group P212121 (IT-Nr.:19) with the unit cell dimensions a = 6.656(1) Å, b = 8.869(1) Å, c = 11.831(2) Å, V = 698.4(2) Å3, Z = 4. The structure of 1 consists of tetrahedral tetraoxochromate dianions, with the Cr at the center of the tetrahedron. Ethylenediammonium dichromate 2 crystallizes in the monoclinic space group C2/c (IT-Nr.:15) with the unit cell dimensions a = 13.464(2) Å, b = 7.791(1) Å, c = 8.639(1) Å, b=108.97(1)o, V = 857.0(2) Å3, Z = 4. In both the compounds, short H-bonding contacts are observed between the oxygen atoms bound to the Cr containing dianion and the H attached to the N atom of the organic dication.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2742-2745

 

Effect of g-irradiation on the thermal decomposition of
MgC2O4 and TiO2 mixture

 S C Moharana, J Praharaj, S Pati & D Bhatta*

 

Simultaneous rising temperature (DTA-TG) technique and gas evolution method have been adopted for studying the thermal decomposition of unirradiated and irradiated MgC2O4 and Mg C2O4 + TiO2 mixtures. The decomposition follows Avrami–Erofeev mechanism (n=2), unaltered in the mixture and irradiated salts, suggesting that nucleation and growth process occurs at the reactant product interface, in two dimensional chain branching manner. Lower doses of irradiation decrease the rate of reaction of the mixture remarkably whereas higher doses increase it. The n-type semiconducting oxide, TiO2, enhances the decomposition of MgC2O4, the rate increasing with increasing concentration (mole %) of the catalyst. The process follows the electron transfer mechanism.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2746-2748

 

Studies on quenching/antiquenching effect of some organic compounds on luminescence of CdS colloids

O P Yadav* & Praveen Kumar Sansanwal

 

Effect of some amines and phenol on luminescence intensity of CdS colloids has been studied. The additives with electron donors groups (-NH2 or -OH) bind to lower energy trap sites which are involved in non-radiative decay, causing enhanced fluorescence.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2749-2750

 

Study of CMC value of binary mixtures of surfactants

 H D Joshi, Komal H Joshi, Geetaben C Desai & C M Desai*

 

The mixtures of surfactants are studied spectroscopically using eosin dye and the CMC [critical micelle concentration] value of the mixtures have been determined by measuring absorbance intensity at lmax of the solution with increasing concentration of the surfactants mixtures keeping dye concentration constant.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2751-2756

 

Reaction of cis-diaqua nitrilotriacetatochromate(III)
with L-ascorbic acid: A kinetic study

Gouri S Brahma,  P Mohanty* & B Nanda

 

The kinetics of the reaction of L-ascorbic acid (H2A) with cis-[Cr(NTA)(H2O)2] has been studied over the range 0.02£[H2A]T £ 0.1 mol dm-3, 3.16 £ pH £ 4.64, 20.0 £ t £ 35.0°C, 0.2 £ I £ 1.0 mol dm-3 (NaClO4) and 10% £[MeOH] £ 50% (v/v). The rate of the reaction is found to increase with the increase in pH of the medium. The reaction is hardly affected by change in ionic strength and dielectric constant of the medium. Activation parameters, DH# and DS# have been found to be 39.4, 34.1, 102.0 kJ mol-1 and -168.00±0.15, -208.0±0.35, 53.0±1.4 J K-1mol-1 for k1, k-1 and k2 path respectively. Anation of cis-[Cr(NTA)(H2O)2] and [Cr(NTA) (OH2)(OH)]- follow Ia and Id path respectively.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2757-2761

 

Investigation of the crystallization kinetics of
 Zn(Phe)SO4·H2O by microcalorimetry

G Shengli*, F Yan, C Sanping, H Rongzu & S Qizhen

 

The crystal growth process of Zn(Phe)SO4·H2O from water and acetone has been investigated using a Calvet microcalorimeter. The heat produced and the rate of heat production during the crystal growth process at 293.15 K, 295.15 K, 298.15 K and 300.15 K have been measured. On the basis of experimental and calculated results, the thermodynamic parameters (the apparent activation enthalpies, the activation entropies, the activation free energies), the rate constant and the kinetic parameters (the activation energies, the pre-exponential) during the crystal growth process have been obtained. The results show that the crystal growth proceeds in accordance with the Burton-Cabrera-Frank dislocation theory.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2762-2766

 

Synthesis, characterization and thermal studies of some new organotin (IV) complexes with aniline N-thiohydrazide and benzaldehyde aniline N-thiohydrazone

N K Kaushik* & A K Mishra

 

The complexes of parachlorotribenzyltin (IV) chloride and parachlorodibenzyl tin (IV) dichloride with aniline N-thiohydrazide (L1), and benzaldehyde aniline N-thiohydrazone (L2) have been synthesized. The complexes have been characterized by elemental analysis and spectral (UV-VIS, IR & NMR) studies. Ligand in the complexes acts as bidentate and coordination takes place through sulphur and terminal nitrogen. These are 1:1 metal ligand complexes. Various thermodynamic parameters have been calculated for the decomposition steps using TG-DTA curves. Activity of all the complexes Vs. Rhizoctonia bataticola fungal strain have been studied and the general order of activity have been deduced.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2767-2771

 

Synthesis, characterization and biological properties of
 N-nicotinoyl-N¢-thiobenzoyl- hydrazine complexes of cobalt(II), nickel(II), copper(II) and zinc(II)

N K Singh*, S B Singh , D K Singh & V B Chauhan

 

A new ligand, N-nicotinoyl-N¢-thiobenzoyl hydrazine (NTB), prepared from nicotinic acid hydrazide and carboxymethyl dithiobenzoate, forms complexes [M(NTB)2Cl2] [M(II) = Co, Ni or Zn], [Cu(NTB-H)Cl], [Ni(NTB-2H)(H2O)2] and [M(NTB-2H)] [M(II) = Co, Cu or Zn], which have been characterized by elemental analyses, magnetic susceptibility, UV-Vis, NMR and IR spectral data. Antimicrobial activity of the ligand and its soluble complexes have been screened against several fungi and bacteria.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2772-2777

 

Synthesis, characterisation and redox behaviour of
mixed ligand complexes of osmium(II/III/IV)

Habibar Chowdhury, Doyel Bose, S K Hafijur Rahaman & Barindra Kumar Ghosh*

 

A group of mixed-tris chelates of osmium(II), (III) and (IV) of the general formula [OsL¢L2]z+ [L¢ = N-((pyridin-2-yl)formyl­idene)aniline (pfan) or N-((pyridin-2-yl)benzylidene)aniline (pban); L = 2,2¢-bipyridyl (bipy), 2-(m-tolylazo)pyridine (tapy) or quinolin-8-olate (oxin); z = 1–3] have been prepared, isolated as their perchlorates and characterised by physicochemical, magnetic and spectroscopic methods. The complexes exhibit several spin-allowed and spin-forbidden charge-transfer transitions in the 1000–200 nm region. In MeCN solutions the chelates display osmium(IV)-osmium(III) and osmium(III)-osmium(II) couples in the range –0.4 to 1.6 V vs SCE. The stability of metal oxidation levels is discussed in terms of the electrochemical results and correlated to the p-acceptor properties of these ligands. On the negative side of SCE, successive ligand reductions in bipy/tapy complexes are observed involving diimine (-N=C-C=N-)/ azoimine (-N=N-C=N-) group.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2778-2780

 

Oxovanadium(IV) and dioxouranium(VI) complexes of some acyclic monoterpenic constituents of essential oil

Premlata Sharma, Mangal Chand & Meena Nagar*

 

A series of complexes of acyclic monoterpenoids, viz. 2-cis-3,7-dimethyl 2,6-octadien-l-al (CDOA); 3,7-dimethyl 6-octen1-ol (Doo) and 3,7-dimethyl 7-hydroxy octane-1-al (DHOA) with vanadyl sulphate and uranyl nitrate have been prepared and characterized by conductometric, pH-metric, spectrophotometric studies, elemental analysis, infrared spectra and magnetic susceptibility. The geometry of complexes is found to be octahedral and square pyramidal. CDOA shows pharmacological activity on central nervous system and cardiovascular system. These terpenoids and their vanadyl and uranyl complexes show activity against fungal strains at 37°C.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2781-2783

 

Molecular complexes of paraquat with sodium purinates

 G Anjaiah, T Veeraiah & G Venkateshwarlu*

 

Molecular complexes of paraquat with sodium purinates have been investigated spectrophotometrically. All the complexes exhibit one charge transfer band each in the region where neither of the components have any absorption. The stoichiometry of each complex is found to be 1:1 from Job’s method. The ionization potentials of the purinate ions have been determined from the position of the CT bands. The stability constants and thermodynamic parameters of the complexes have been determined from the absorption studies on CT bands. The shifts in the position of CT band of PQ-purinate and the variation of its stability constant with substituents are explained in terms of the number of substituents, the ionization of substituents, the mesomeric effect of substituents and the hyperconjugation of substituents in the purine ring.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2784-2787

 

Inhibitive effect of PEG on the corrosion of aluminium in acidic medium

Jyotsna Shukla, K S Pitre* & Praveen Jain

 

The mechanism of corrosion of aluminium and the effect of polyethylene glycol (PEG) polymer as corrosion inhibitor in acidic medium has been studied using the weight loss method, potentiodynamic and galvanostatic polarization measurements. Differential pulse polarography (DPP) and differential pulse anodic stripping voltammetry have been used for the study of corrosion rates for the corrosion of aluminium in acidic medium at short time intervals. Corrosion of B-265 aluminium in 60% HNO3 solution with and without polyethylene glycol inhibitor at short time interval has been reported. The corrosion inhibition efficiency of PEG is 94% after 24 h.

 

 

 

Indian Journal of Chemistry 

Vol. 42A, November 2003, pp. 2788-2791

 

The effect of counterion and hydrogen ion concentrations on the capacity factor of weak monoprotic organic acids in ion‑pair reversed phase chromatography

Welford‑Abbey Lolo Izonfuo* & HappyJohn Timinebi Eke

 

The weak monoprotic organic acids, benzoic and salicylic acids, have been ion‑paired with varying concentrations of tetrabutylammonium (TBA) ion and retained in a reversed phase liquid chromatographic column. The capacity factors of the acids increase with increase in counterion concentration up to a maximum of 10 millimoles of TBA in the mobile phase. The capacity factors decrease gradually with further increase in counterion concentration beyond 10 millimoles. The capacity factor of both acids is found to be directly proportional to the concentration of the ion‑pairing reagent until the ion‑pair is quantitatively and completely formed. Decrease in the capacity factor has been predicted from a derived equation and compared with the measured capacity factors. The results confirm that the derived equation earlier published correctly describes the behaviour of weak monoprotic organic acids when ion‑paired with a counterion in reversed phase chromatographic column. The dependence of the capacity factor of the acids on the pH of the mobile phase is characteristically sigmoidal in shape. The presence of a counterion the mobile phase however appears to have little effect on the capacity factor of the acids at pH values lower than 6.