Indian Journal of Chemistry

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

 

VOLUME 41A

NUMBER 9

SEPTEMBER 2002

CONTENTS

                                                       Rapid Communication

 

1763

 

Aryl monosulphides and symmetrical disulphides based second order nonlinear optical chromophores with transparency in the visible

 

 

Ramanathan Sudharsanam, Srinivasan Chandrasekaran & Puspendu Kumar Das*

 

 

 

A series of aryl monosulphides and disulphides have been synthesized and characterized. Their molecular hyperpolarizability (b) has been measured in solution with the hyper-Rayleigh Scattering technique and also calculated by semiempirical AM1 method. These compounds show moderate b values and excellent transparency in the visible region.

 

 

                                                                  Papers

 

1767

 

Wiener-type topological indices of phenylenes

 

 

 

 

Boris Furtula, Ivan Gutman*,
ˇeljko Tomovića, Aleksander Veselb &
Igor Pesekb

 

 

 

The Wiener index W of a phenylene (PH) has earlier been shown to depend in an exact manner on the Wiener indices of its hexagonal squeeze (HS) and inner dual (ID). The analogous dependency for a class of Wiener-type indices Wl  (Wl = W for l=1) is now examined. It is shown that some features of the dependency of W(PH) on W(HS) and W(ID) are maintained for all values of l, whereas some are violated.

 

1773

 

Quantum-chemical investigation of electrophilic addition of bromine to norbornadiene

 

 

 

R. Abbasoğlu & S.Savaşkan Yılmaz

 

 

 

1777

 

Simulation of the infrared spectra of thioacetamide by the extended molecular mechanics method

D N Sathyanarayana* & E Ganeshsrinivas

 

The infrared spectra of the matrix-isolated species of thioacetamide and its 2H, 13C and 15 N –isotopic molecules have been studied by the extended molecular mechanics method. The equilibrium structure, vibrational frequencies, dipolemoment and infrared band intensities have been calculated in good agreement with the experiment.  

 

1784

 

MC model studies of  CeO2 -metal interaction

 in Pt-Rh  nanocatalysts

 

 

 

 

 

 A De Sarkar &  Badal C Khanra*

 

 

 

Through the MC simulation studies of CeO2-metal interaction  on the surface composition of Pt-Rh  nanocatalysts,  it has been  shown  that the base of the Pt-Rh nanocatalysts  gets enriched with Pt and increases with the strength of the metal support interaction; and that  the  Pt fraction of the exposed surface of the Pt-Rh nanocatalysts  is large for weak metal-support interaction, but decreases with strength of metal -support interaction.   

 

 

1789

 

Preparation of organic polymer/inorganic oxide conductive composites

 

Al-Nakib Chowdhury* , J M Arifur Rahman

& Md. Aminur Rahman

 

 

Conductive composites based on organic conducting polymer and inorganic oxide have  been prepared and characterized. Even after incorporating insulating silica, the composites exhibit electrical conductivity comparable to that of the conventional semiconductors.

 

1795

Catalytic activity of an immobilized a-amylase on mesoporous silicas

 

 

H M Mody, K H Mody , R V Jasra*,
Hyuan June Shin & Ryoo Ryong

 

 

Three silica supports, namely, SBA15, silica-N and silica-AC, having different pore size distribution have been hydrothermally synthesized. a-Amylase has been immobilized after amino functionalization of silica surface by covalent bonding through glutaraldehyde.. Amino functionalization and enzyme immobilization result in a decrease in surface area, pore volume and pore size for all the samples.

1804

 

Osmotic and activity coefficient studies on the aqueous solutions of tetramethylurea at
298.15 K

 

 

 

 

 

K J Patil*, A M Sargar & D H Dagade

 

 

 

The osmotic coefficients and densities of  aqueous solutions of tetramethylurea (TMU) in the concentration range 0.1 to 8.0 m at 298.15 K have been experimentally determined and the data used to calculate apparent and partial molar volumes, activities and activity coefficients of water and TMU as a function of concentration of TMU. The values of virial coefficients indicate that pairwise interaction between TMU molecules and water structure making effect is  more prominent than triplet and higher order interactions in the studied concentration range of aqueous-TMU solutions.

 

1812

A study on volumetric and compressibility properties of some lithium salts in N, N-dimethylacetamide at 25oC

 

 

 

 

Debashis Das, Subrata  K Ray  &
Dilip K Hazra*

 

 

 

Apparent molar volumes and apparent molar adiabatic compressibilities have  been  determined for five lithium salts in N,N-dimethylacetamide  at  25oC from density and sound  velocity measurements. It is observed that these salts have appreciable ion-ion interaction in this medium and comparatively larger size anions have greater  electrostatic solvation in contrast to electrostriction effect  where smaller size anions  predominate over others.

 

1816

Interaction of zinc with cysteinylglycine and histidine containing di-peptides : Relevance to zinc binding sites in transcription factor III A

 

 

 

 

P Rabindra Reddy* & S Krishna Mohan

 

 

 

1821

 

Synthesis of a new chelating resin containing nitrogen and sulphur donor sites and its application for the removal of inorganic arsenic from natural water

 

 

 

Bhim Chandra Mondal & Arabinda K Das*

 

 

1826

 

Synthesis, spectroscopic, luminescence, electrochemical and antitumour/anti-HIV studies of some new monomeric and dimeric ruthenium(II) complexes of 3-hydroxy-4¢-benzyloxy flavone containing nitrogen, oxygen and sulphur donors as co-ligands

 

 

L Mishra* & Ashok K Singh

 

 

 

Notes

1832

 

H2S gas sensing characteristics of WO3 thick-films

 

 

 

Sang-Do Han*, Ishwar Singh, Han-Soo Kim, Sun-Tae Kim, Young-Ho Jung &
Byeong-Kwon Kim

 

1837

 

Non-isothermal decomposition study of

iron (III) oxalate and rare earth oxides mixture

 

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

 

 

Iron(III) oxalate and rare earth oxide (Sm2O3, Gd2O3, Dy2O3) mixtures decompose in two different stages following contracting volume and first order kinetics respectively. Catalytic activity of the oxides is in the order: Sm2O3>Gd2O3>Dy2O3.

1841

 

Substituent effects on the spontaneous cleavage of benzyl-gem-dibromides in aqueous solution

 

 

R Sanjeev & V Jagannadham*

 

 

 

1845

 

Bio-acoustical studies of some novel 3d-metal chelates in solution

 

 

 

A  P Mishra* & S K Gautam

 

 

 

Density and ultrasonic velocity of furfurylidene thio- acetamide, 3-nitrobenzylidene-2-aminothiazole and 4-chlorobenzylidene-thioacetamide and their complexes with Co(II), Ni(II) and Cu(II) have been measured in methanol at 303.15 K. The results are discussed in the light of solute-solvent interaction and structural effects on the solvent in solution.

 

 

1850

 

Crystallographic characterization of divalent

organosamarium compound (C5H5)2Sm(THF)2

 

 

 

 

 

S Jagannatha Swamy

 

 

 

1855

 

Oxidation of cysteinato complexes of dimeric molybdenum(V) by hexachloroiridate(IV) in aqueous perchlorate solution.

 

Olayinka A Oyetunji *  & Jeffrey J Tore  

 

 

 

 

Mo2V  +  IrIVŪ MoVMoVI    +  IrIII

MoVMoVI            MoV    +    MoVI

MoV   +    IrIV             MoVI    +      IrIII              

 

 

1860

 

Synthesis of single strapped 21-thia tetraphenylporphyrin systems

 

 

 

 

 

P Boobalan, Iti Gupta & M Ravikanth*

 

 

1864

 

Synthesis, characterization and catalytic application of tin phosphate

 

Sonal M Patel & Uma V Chudasama*

 

 

 

Tin phosphate has been synthesized and characterized.. Esterification reaction has been chosen as a model reaction and acetate esters of ethyl, n-propyl, n-butyl and benzyl alcohol have been prepared by varying the mole ratio of alcohol to acid and amount  of catalyst.

 

 

1867

 

Simultaneous detection of Anatoxin-a and Microcystin-LR from cyanobacterial strains using high-performance liquid chromatography and LC-ESI-MS method

 

Manisha Nivsarkar, Jyotiranjan Acharya,
PV Lakshmana Raoa, & M P Kaushik
*

 

 

 

A method has been developed for the simultaneous extraction, purification and detection of cyanobacterial toxins (hepatotoxin and neurotoxin) from a single batch of Microcystis aeruginosa and Anabaena flos-aquae.

 

1871

 

Spectrophotometric determination of trace amounts of tellurium based on its catalytic effect in the reduction of gallocyanine with sodium sulphide

Ali A Ensafi1*, M Saber Tehrany &
M Keyvanfard

 

 

 

A simple and sensitive kinetic spectrophotometric method for the determination of ultra trace amounts of tellurium(IV) has been proposed. It is based on the catalytic effect of Te(IV) on the reduction of gallocyanine by sodium sulphide.

 

1874

 

Spectrophotometric determination of thorium(IV) using 3-hydroxy-2-(2¢-thienyl)-4H-chromen-4-one

 

Amita Garg & L R Kakkar*

 

 

 

A spectrophotometric method has been developed to determine thorium using 3-hydroxy-2-(2¢-thienyl)-4H-chromen-4-one (HTC) which forms a 1:4 yellow complex in dilute acetic acid solution with lmax at 430 nm. The method is free from the interference of a large number of metal ions

Authors for correspondence are indicated by (*)

 

 

 


 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1763-1766

 

 

Rapid Communication

 

Aryl monosulphides and symmetrical disulphides based second order nonlinear optical chromophores with transparency in the visible

 

Ramanathan Sudharsanam, Srinivasan Chandrasekaran & Puspendu Kumar Das*

Received  4 July  2002

A series of aryl monosulphides and disulphides have been synthesized and characterized. Their molecular hyperpolarizability (b) has been measured in solution with the hyper-Rayleigh Scattering technique and also calculated by semiempirical AM1 method. The trend in the observed and calculated values of first hyperpolarizability of these compounds has been found to be in good agreement. These compounds show moderate b values and excellent transparency in the visible region.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1767-1772

Papers

Wiener-type topological indices of phenylenes

Boris Furtula*a, Ivan Gutmana, ˇeljko Tomovića, Aleksander Veselb & Igor Pesekb

Received 3 June 2002

The Wiener index W of a phenylene (PH) has earlier been shown to depend in a mathematically exact manner on the Wiener indices of its hexagonal squeeze (HS) and inner dual (ID). We now examine the analogous dependency for a class of Wiener-type indices Wl , where l is a variable parameter (Wl = W for l=1) is examined now. It is shown that some features of the dependency of W(PH) on W(HS) and W(ID) are maintained for all values of l , -5 £ l £ +5 , whereas some are violated.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1773-1776

 

Quantum-chemical investigation of electrophilic addition of bromine to norbornadiene

R. Abbasoğlu & S.Savaşkan Yılmaz

Received 28 September 2001; revised 19 April 2002

In the electrophilic addition of bromine to norbornadiene, the intermediate molecular complexes between norbornadiene and bromine have been investigated and their stable configurations determined using AM1 semiempirical method. The geometric parameters and stabilization energies of the complexes have been calculated. The exo and endo adducts are found to be nearly isoenergetic, but an exo selectivity has been observed. The cationic intermediates of the reaction have been studied by ab initio SCF method in STO-3G and STO-3G* basis and also by MNDO semiempirical route. Exo-bromonium cation is found to be more stable than endo-bromonium cation according to both the methods. The results obtained indicate that a multicenter non-classical bromocarbonium cation formed by the rearrangement of exo-bromonium cation is the most stable one among the cationic intermediates. It is likely that the ionic addition reaction proceeds via the non-classical bromocarbonium ion and results in the formation of the rearranged products.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1777-1783

 

Simulation of the infrared spectra of thioacetamide by the extended molecular mechanics method

D N Sathyanarayana* & E Ganeshsrinivas

Received 4 June 2002

The infrared spectrum of the matrix-isolated species of thioacetamide has been simulated using the extended molecular mechanics method. The equilibrium structure, vibrational frequencies, dipole moment and infrared absorption intensities of thioacetamide have been calculated in good agreement with the experiment. The vibrational frequencies and infrared absorption intensities for the isotopic molecules 13CH3CSNH2, CH3CS15NH2 and 13CH3CSND2 have also been calculated consistent with the experiment. The infrared spectra of the matrix isolated species of N- and C- deuterated isotopomers of thioacetamide, CH3CSND2 and CD3CSNH2 have also been simulated in satisfactory agreement with the experimental spectra.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1784-1788

 

 MC model studies of  CeO2 -metal interaction  in Pt-Rh  nanocatalysts

 

   A  De Sarkar &  Badal  C  Khanra*

Received 6 February 2002; revised 6 June 2002

 

               MC simulation technique has been used to investigate the effects of gradual  reduction of Pt-Rh/ceria and the concomitant change in the metal-support interaction on the composition  of  Pt-Rh nanocatalysts .  For all nanoparticle sizes the Pt fraction at the basal layer of the Pt50Rh50  systems is found to increase with metal-support interaction. The Pt fraction  is highest at the basal layer and  reaches approximately the particle-average value of 50% at the fourth layer from the base.  In the rest of the particle surface, which is exposed to the reacting gases, the Pt fraction is highest when  metal support interaction  is weak; and decreases gradually with higher strength of metal support interaction. 

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1789-1794

 

Preparation of organic polymer/inorganic oxide conductive composites

Al-Nakib Chowdhury* , J M Arifur Rahman

and

Md. Aminur Rahman

 

Received 25 February 2002; revised 30 April 2002

 

Preparation of conductive composites based on organic conducting polymer and inorganic oxide has been described. The composite materials thus prepared have been characterized by a wide range of experimental techniques including elemental analysis, density measurement, UV-vis and IR spectroscopy, X-ray and sedimentometry. Even after incorporating insulating silica, the composites exhibit electrical conductivity comparable to that of the conventional semiconductors. In contrast to the bulk polymer, the composites show relatively superior environmental stability when exposed to ambient atmosphere. The composites have been further characterized for their surface area; in this connection, adsorption of methylene blue on a composite matrix has been examined.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1795-1803

Catalytic activity of an immobilized a-amylase on mesoporous silicas

H M Mody, K H Mody & R V Jasra*

and

Hyuan June Shin & Ryoo Ryong

Received 19 November 2001; revised 28 May 2002

Three silica supports, namely SBA15, silica-N and silica-AC, having different pore size distribution have been hydrothermally synthesized. a-Amylase, used for hydrolysis of starch, has been immobilized after amino functionalization of silica surface by covalent bonding through glutaraldehyde. The silica, before, and after modification has been characterized by XRD analysis, BET surface area and BJH pore size distribution by N2 sorption at 77K. SBA15 and modified SBA15 show ordered hexagonal structure whereas the other two silica samples, viz., silica-N and silica-AC are found to be XRD amorphous. Pore size distribution of the studied silica range from 76 to 300Å. Amino functionalization and enzyme immobilization resulted in a decrease in surface area, pore volume and pore size for all the samples. On SBA15 and silica-N, enzyme immobilization was on external surface only whereas on silica-AC, internal pores were found to be accessible to the enzyme molecules. Specific activity of a-amylase was observed to follow the order silica-AC > silica-N > SBA15. Immobilized a-amylase exhibited higher operational stability in the order of SBA15 > silica-AC > silica-N. Immobilized a-amylase exhibited comparatively less specific activity than that of the free enzyme.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1804-1811

Osmotic and activity coefficient studies on the aqueous solutions of tetramethylurea at 298.15 K

K J Patil*, A M Sargar & D H Dagade

Received 10 April 2002; revised 3 July 2002

      The osmotic coefficients and densities of good precision of aqueous solutions of tetramethylurea (TMU) in the concentration range 0.1 to 8.0 m at 298.15 K have been experimentally determined and the data used to calculate apparent and partial molar volumes, activities and activity coefficients of water and TMU as a function of concentration of TMU. It has been observed that partial molar volume of solvent and solute go through a maximum and a minimum, respectively, at about 0.055 mole fraction of TMU. The activity coefficient values for H2O increase while those of TMU decrease with increase in concentration of TMU. These results are compared with those of aqueous urea solutions and are in agreement with literature values  indicating the presence of hydrophobic interactions in H2O-TMU solutions. Excess free energy of mixing of TMU in water has been calculated using activity data at 298.15 K and is found to decrease as a function of TMU concentration in the studied concentration range. The values for the attractive and repulsive contributions to the solute-solvent interaction have been estimated and data is compared with other non-electrolytes. Further, applying McMillan-Mayer theory of solutions to the data osmotic second and third virial coefficients for TMU have been obtained. The values of virial coefficients, on decomposition into attractive and repulsive contributions to solute-solute interactions, indicate that pairwise interaction between TMU molecules and water structure making effect are more prominent than triplet and higher order interactions in the studied concentration range of aqueous-TMU solutions.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1812-1815

A study on volumetric  and compressibility properties  of some lithium salts in N,N-dimethylacetamide at  25oC

Debashis Das, Subrata Roy & Dilip K Hazra*

Received 10 April 2002; revised 17 May 2002

            Apparent molar volumes (fv) and apparent molar adiabatic compressibilities (fk) have been determined for solutions of some lithium salts (LiCl, LiBr, LiI, LiClO4, LiBF4)  in N,N-dimethylacetamide at 25oC from density and sound  velocity measurements. Limiting apparent molar volumes (fv0)  of the  salts  have been obtained from fv vs  Öc   curves and separated into ionic contributions. The apparent molar compressibilities at infinite dilution, fk0 was evaluated by fitting  fk against  Öc by the method of least-squares and also the ionic values reported. The results indicate that as the size of the anion increases (cation being the same)  electrostatic solvation has an increasing tendency and compressibility of the solution becomes more decreased. The data have been quantitatively explained in terms of solute-solvent interactions along with the degree of  disorder  in the solvent structure.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1816-1820

 

 

Interaction of zinc with cysteinylglycine and histidine containing di-peptides : Relevance to zinc binding sites in transcription factor III A

 

P Rabindra Reddy* & S Krishna Mohan

 

Received 25 February; revised 2 May 2002

 

The interaction of zinc with dipeptides, histidylalanine and histidylleucine has been investigated the binding modes and the stability factor have been determined by pH metry and 1H NMR.  The interaction of Zn with these ligands in the presence of cysteinylglycine has also been investigated as a model for zinc centre in TFIIIA.  The findings are that these dipeptides act as bidentate ligands both in binary and ternary mode.  The coordinating sites and geometry around Zn are assigned.  The conclusion from this model are in agreement with Zn binding sites in TFIIIA.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1821-1825

 

 

Synthesis of a new chelating resin containing nitrogen and sulphur donor sites and its application for the removal of inorganic arsenic from natural water

Bhim Chandra Mondal & Arabinda K Das*

Received 22 October 2001; revised 21 May 2002

Chloromethylated polystyrene divinyl benzene (3 %) has been functionalised through –NH-CH2 – bond with bis-(2-aminophenyl)disulfide. The resulting chelating resin has been characterised by elemental analyses, infrared spectra and metal ion capacity. The sorption capacities for both  As (III) and As (V) have  been determined using batch technique and they show a strong sorption at pH 4.5. The effect of the presence of co-existing ions have also been examined. The concentration of each of the arsenic species has been determined by HG-AAS. The sorption and desorption cycles have been examined using a column packed with the resin without any loss of column performance which indicates the possibility for its reuse. The developed column technique has been used for the removal of arsenic species from natural water.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1826-1831

 

Synthesis, spectroscopic, luminescence, electrochemical and antitumour/anti-HIV studies of some new monomeric and dimeric ruthenium(II) complexes of 3-hydroxy-4¢-benzyloxy flavone containing nitrogen, oxygen and
sulphur donors as co-ligands

 

L Mishra & Ashok K Singh

Received 22 January 2002; revised 11 April 2002

Series of mononeric and dimeric ruthenium (II) complexes of 3-hydroxy-4¢-benzyloxy-flavone (LH) containing dimethylsulfoxide (DMSO), 2-mercapto-benzimidazole (MBZH), N,N-diethyldithiacarbamate (DTC) and pentane-2,4-dione (acacH) as co-ligands are synthesised and characterised by IR, 1H NMR, UV/vis, FAB-mass spectral and elemental analysis data. The luminescence, electrochemical and antitumour/anti-HIV properties of the complexes are also studied.

 

 

 

Notes

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1832-1836

 

H2S gas sensing characteristics of WO3 thick-films

 

Sang-Do Han*, Ishwar Singh, Han-Soo Kim, Sun-Tae Kim,

Young-Ho Jung & Byeong-Kwon Kim

Received 28 January 2002; revised 28 April 2002

 

The WO3 thick films fabricated as gas sensor exhibit good sensitivity for H2S over a wide range of operation temperatures. The sensor characteristics are influenced with the microstructure and the thickness of the WO3 films. The sensitivity of the sensor decreases with increase in thickness of the films. Relative variation of the fabricated sensor’s resistance at varying temperatures between 240˚ to 420˚ with heater power and with varying concentrations of the H2S gas under analysis have been derived. The best results for sensing H2S gas in the concentration range between 0.05 to 25 ppm have been obtained when the film thickness is kept between 20-22mm. The response of WO3 films for sensing H2S gas is not influenced by the presence of several testing reference gases like SO2 up to 12 ppm, NH3 up to 10.8 ppm, CO up to 19 ppm and CH4 up to 187 ppm. However, presence of NOx interferes when present in ambient  air.    Addition of small amounts of SnO2 (3-10%), however, corrects the result and H2S can be determined in the presence of NOx up to 11 ppm.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1837-1840

 

Non-isothermal decomposition study of iron (III) oxalate and rare earth oxides mixture

 

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

Received 20 November 2001; revised 22 April 2002

 

                                                                        The catalytic activity of rare earth oxides (Sm2O3, Gd2O3, Dy2O3) on the non-isothermal decomposition of iron (III) oxalate hydrate has been studied by adopting rising temperature technique. It is found that the reaction takes place in two different stages. Analysis of the data in the light of theories of various kinetic models indicates that the first stage follows contracting volume model (R3) whereas the second one obeys first order (F1) process. Admixtures enhance the rate of reaction of both the stages. Catalytic activity is of the order: Sm2O3>Gd2O3>Dy2O3. The plausible mechanism of decomposition and the effect of rare earth oxides on the process have been discussed in detail.

 

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1841-1844

 

Substituent effects on the spontaneous cleavage of benzyl-gem-dibromides in aqueous solution

R Sanjeev & V Jagannadham*

Received 6 February 2002; revised 8 May 2002

The a-bromobenzyl cations have been produced in aqueous solution by chemical initiation (solvolysis) of benzyl-gem-dibromides. The solvolysis reactions of benzyl-gem-dibromides in water proceed by a stepwise mechanism through a-bromobenzyl carbocation intermediates, which are captured by water to give the corresponding benzaldehydes as the sole detectable products. Rate constant ratios kBr/ks (M-1) for partitioning of the carbocation between reaction with bromide ion and reaction with water have been determined by analysis of bromide common ion inhibition of the solvolysis reaction. The rate constants ks (s-1) for the reaction of the cation with solvent water were determined from the experimental values of kBr/ks and ksolv, for the solvolysis of the benzyl-gem-dibromides, using kBr = 5 x 109 M-1 s-1 for diffusion-limited reaction of bromide ion with benzyl carbocations. Calculation and discussion of selectivities, kBr/ks, of the a-bromobenzyl cations, activation parameters for solvolysis step and for addition of water to the cation are some of the salient features not reported earlier. Effect of substituents is also discussed in terms of Hammett equation for both the steps.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1845-1849

 

Bio-acoustical studies of some novel 3d-metal chelates in solution

P Mishra* & S K Gautam

Received19 June 2001 ; revised 1 May 2002

 

Density and ultrasonic velocity of furfurylidene-thioacetamide (FTA), 3-nitrobenzylidene-2-aminothiazole (NAT) and 4-chlorobenzylidene-thioacetamide (CTA) and their complexes with Co(II), Ni(II) and Cu(II) have been measured in methanol at 303.15 K. The apparent molar volume, acoustic impedance, adiabatic compressibility, intermolecular free length, molar sound velocity (Rao’s constant), molar compressibility (Wada’s constant) and solvation number have been calculated from the experimental data. The results are discussed in the light of solute-solvent interaction and structural effects on the solvent in solution.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1850-1854

 

Crystallographic characterization of divalent

organosamarium compound (C5H5)2Sm(THF)2*

 

S Jagannatha Swamy

 

Received 20 November 2001; revised 8 April 2002

                                                                                                  

The single pot reaction between SmX2 (X = Cl-, I-) and tBuLi in THF at -40oC, followed by the addition of C5H5- Na+ results in a dark red solution. Leaving the concentrated reaction mixture at –25oC for two days in a deep freezer results in the formation of the crystals of the compound, (C5H5)2Sm(THF)2. The compound is  insoluble in any solvent and it has been characterized by conventional methods. The crystals are monoclinic with space group C2/c, and a = 13.416(1), b = 9.644(1), c = 14.129(2) pm, β = 109.873(9)o and z = 4 for rcalcd = 1.64 g cm-3. Least squares refinement on the basis of 1804 observed reflections has  led to a final R value of 0.037 and Rw = 0.054.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1855-1859

 

Oxidation of cysteinato complexes of dimeric molybdenum(V) by hexachloroiridate(IV) in aqueous perchlorate solution.

 

Olayinka A Oyetunji * & Jeffrey J. Tore

 

Received 19 November 2001; revised 2 May 2002

 

The kinetics and mechanism of the oxidations of [Mo2(O)2(m-O)2(cys)2]2- (Mo2O4), [Mo2(O)2(m-O)(m-S)(cys)2]2- (abbreviated Mo2O3S), and [Mo2(O)2(m-S)2(cys)2]2- (Mo2O2S2) by [IrCl6]2- have been studied in aqueous perchlorate solution at ionic strength, I = 1.0 mol dm-3 (LiClO4) and  [H+] = 0.2 mol dm-3 (HClO4). The effects of the replacement of the ethylenediaminetetraacetate (EDTA) ligand with the cysteinato (cys) ligand, as well as the progressive substitution of the bridging oxygen atoms with sulphur atoms, are discussed. At 25.0oC, the values (in dm3 mol-1 s-1) of  k1,  the electron transfer rate constants, are 8.90±0.07, 8.09±0.18, and 7.54±0.06 for Mo2O4, Mo2O3S, and Mo2O2S2, respectively.  Similarly, k-1/k2 , a measure of the stability  of the intermediates formed in the reactions, have values of  (1.02±0.03) x 103, (1.63±0.09) x 103, and (1.81±0.04) x 103, (dm3 mol-1), for Mo2O4, Mo2O3S, and Mo2O2S2 , respectively. Activation parameters, DH¹ and DS¹, are 6.64±0.72 kJ mol-1 and  –204±21 J K-1 mol-1  for oxidation of  Mo2O4, 9.86±0.28 kJ mol-1 and  –194±18    J K-1 mol-1 for Mo2O3S, and 10.75±0.15 kJ mol-1 and  –192±17 J K-1 mol-1 for Mo2O2S2.  All reactions occur via outer-sphere electron transfer.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1860-1863

 

 

Synthesis of single strapped 21-thia tetraphenylporphyrin systems

P Boobalan, Iti Gupta & M Ravikanth*

                                    Received 8 October 2001; revised 14 March 2002

Synthesis and characterization of two single strapped 21-thia tetraphenylporphyrins have been reported.  The two adjacent phenyls that are present at the meso position of 21-thia tetraphenylporphyrin are linked by either rigid aromatic group or flexible alkyl chain.  Absorption and fluorescence studies indicated that the rigid aromatic group induced more nonplanarity in the porphyrin ring than flexible alkyl chain.

 

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1864-1866

 

Synthesis, characterization and catalytic application of tin phosphate

Sonal M Patel & Uma V Chudasama*

Received 10 December 2001; revised 5 March 2002

Tin phosphate, a tetravalent metal acid salt, has been synthesized and characterized. The H+ ions contained in the structural hydroxyl group of the tma salts are labile and hence the material can be used as a solid acid catalyst. Esterification reaction has been chosen as a model reaction and acetate esters of ethyl, n-propyl, n-butyl and benzyl alcohol have been prepared by varying the mole ratio of alcohol to acid and amount  of catalyst.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1867-1870

 

Simultaneous detection of Anatoxin-a and Microcystin-LR from cyanobacterial strains using high-performance liquid chromatography and LC-ESI-MS method

Manisha Nivsarkar, Jyotiranjan Acharya, PV Lakshmana Raoa, & M P Kaushik*

Received 17 January 2002; revised 6 June 2002

A method has been developed for the simultaneous extraction, purification and detection of cyanobacterial toxins (hepatotoxin and neurotoxin) from a single batch of Microcystis aeruginosa and Anabaena flos-aquae. After several extractions and adsorption on to C-18 sep-pak cartridge, the cyanobacterial toxins have been detected both by high performance liquid chromatography and LC-ESI-mass spectrometry. Anatoxin-a and Microcystin-LR have been detected in UTEX-2383 and UTEX-2385 strains of Anabaena flos-aquae and Microcystis aeruginosa respectively.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1871-1873

 

Spectrophotometric determination of trace amounts of tellurium based on its catalytic effect in the reduction of gallocyanine with sodium sulphide

Ali A Ensafi*, M Saber Tehrany & M Keyvanfard

Received 24 December 2001; revised 2 April 2002

A simple and sensitive kinetic spectrophotometric method for the determination of ultra trace amounts of tellurium(IV) has been proposed. It is based on the catalytic effect of Te(IV) on the reduction of gallocyanine by sodium sulphide. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 618 nm. The method allows the determination of tellurium concentration in the range 2.0-200 ng/ml, with the detection limit of 1 ng/ml. The relative standard deviation for ten replicate determinations of 20.0 and 50.0 ng/ml Te(IV) is 1.7% and 1.1%, respectively. The method has been applied to determination of tellurium in water samples.

 

Indian Journal of Chemistry

Vol. 41A, September 2002, pp. 1874-1876

 

Spectrophotometric determination of thorium(IV) using 3-hydroxy-2-(2¢-thienyl)-4H-chromen-4-one

 

Amita Garg & L R Kakkar*

Department of Chemistry, Kurukshetra University, Kurukshetra 136 119, (Haryana), India

Received 23 October 2001; revised 21 February 2002

A spectrophotometric method has been developed to determine thorium using 3-hydroxy-2-(2¢-thienyl)-4H-chromen-4-one (HTC) which forms a 1:4 yellow complex in dilute acetic acid solution with lmax at 430 nm. The method is free from the interference of a large number of metal ions of interest. Molar absorptivity and Sandell’s sensitivity of the complex are 3.95´104 L mol-1 cm-1 and 0.0059 (g cm-2, respectively.