Total visitors: 4,368  since 31-01-05

Indian Journal of Chemistry

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

 

VOLUME 44A

NUMBER 1

January 2005

 

CONTENTS

 

Papers

 

9

 

Relation between electron and energy contents of hexagons in catacondensed benzenoid hydrocarbons

 

 

Boris Furtula, Ivan Gutman* & Nedžad Turković 

 

 

 

13

 

Relation between electron and energy contents of hexagons in pericondensed benzenoid hydrocarbons

 

  

 

 

 

 

Ivan Gutman*, Svetlana Milosavljević,  Boris Furtula & Nataša Cmiljanović

 

 

 

 

18

 

 

Synthesis, crystal structure and DNA hydrolysis activity of ternary (N-salicylidene-L-methioninato)copper(II) complexes of heterocyclic bases

 

  

 

Rabindranath Pradhan, Anitha M Thomas, Arindam Mukherjee, Shanta Dhar, Munirathinam Nethaji & Akhil R Chakravarty*

 

 

 

 

27

 

 

Dynamic processes of H-atom site exchange in trans dihydrogen hydride complex of ruthenium

 

 

 

V Sivakumar & Balaji R Jagirdar*

 

 

 

 

34

 

 

Influence of cerium precursor on the size and solid solubility of transition metals in combustion synthesized Ce1-xMxO2-d (M = Cu, Pd) nano crystallites: Enhancement of redox properties and catalytic activity

  

Arup Gayen, Tinku Baidya, A S Prakash, N Ravishankar & M S Hegde*

 

 

 

 

49

 

 

Competitive energy dynamics in IRMPD of UF6

 

 

 

 

 

 

Sisir K Sarkar

 

 

 

Infrared Multiphoton Dissociation  has been modeled on a rate equation formalism and the multiphoton dissociation rate constants for UF6 with 16 mm laser have been estimated. MPD of UF6 occurs with a threshold fluence of
1-1.2 J cm-2. Considering various time scales involving excitation, collisional deactivation and life time of energized 235-UF6  molecule, the extent of selectivity loss has been estimated.

 

58

 

Microstructure characterization of poly(2-N-carbazolylethyl acrylate) by two dimensional NMR spectroscopy

 

 

 

 

 

 

A S  Brar*, M Markanday & S Gandhi

 

 

 

 Notes
 

 

64

 

Artificial neural network aided design of a multi-component catalyst for the steam reforming of methanol

 

 

 

 

Sh Jooya & F Gobal*

 

 

 

 

67

 

Study on lyotropic liquid crystals of the
3-octyloxy-2-hydroxypropyl trimethyl-ammo-nium bromide-n-hexanol-water system

 

 

 

 

Bao-Lin Yin, Xi-Lian Wei, Qing Sang & De-Zhi Sun*

 

 

 

 

71

 

Os(VIII)-catalysis on the oxidation of some diaryl sulphoxides with bromamine-B in alkaline medium

 

Subbiah Meenakshisundaram* & Ramakrishnan Markkandan

 

 

 

BAB + Ph2SO      Ű  C1

          k2

C1 + OsO4  ®    C2

               fast

C2      ®    OsO4  + Ar2SO2 +   RNH2 + Na+ + Br-

 

76

 

Oxygenation reactions of cobalt(II) tetraen chelates generated on flash photolysis and continuous photolysis of cobalt(III) complexes in different solvents

 

Chelli Janardhana*, S Jagadeeswara Rao,
V Venkatesh, J Sai Kiran & R Sai Sathish

 

 

 

80

 

Kinetics of Ru(III) catalysed oxidation of phenethyl alcohol and para-substituted phenethyl alcohols by Ce(IV) in aqueous nitric acid medium

 

 

 

N Vijaya Bhaskar Rao  &  M Anand Rao*

 

 

 

 

85

 

Synthesis and characterization of some new Cu(II) complexes of azo dyes derived from
1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one

 

 

 

  

 

 

M L Harikumaran Nair,*, George Mathew & M R Sudarsana Kumar

 

 

 

 

90

 

Mixed ligand triphenylphosphine/arsine Schiff base complexes of ruthenium(II) and their catalytic activities towards oxidation of alcohols

 

 

P Viswanathamurthi, A Geetha,  R Karvembu & K Natarajan*

 

 

 

 

94

 

Synthesis, characterization and solid state structural studies of oxovanadium (IV) – O, N donor schiff base chelates

 

  

 

A P  Mishra* & L R Pandey

 

 

VO(IV)-complexes with the Schiff bases viz.,
4-chlorobenzylidene-2-amino-4-chlorophenol, 4-dimethyl-aminobenzylidene-2-aminophenol and 2-hydroxy-1-naphthylidene-4-bromoaniline have been synthesized and characterized.. All the three ligands behave as bidentate coordinating through O and N donor. The proposed geometry for the complexes is square pyramidal.

 

 

98

 

Determination of small quantities of nicotinic acid in presence of nicotinamide by modified Konig reaction

 

  

Seemab Khan, M K Rai*, V K Gupta & J K Rai

 

 

 

A modified sensitive spectrophotometric method for the determination of nicotinic acid and nicotinamide in sub-microgram levels is described. The method is free from interference of common diverse ion and has been satisfactorily applied to the determination of nicotinic acid in presence of nicotinamide in food, blood, urine and pharmaceuticals.

 

102

 

Announcements

 

 

Authors for correspondence are indicated by (*)

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 9-12

 

Relation between electron and energy contents of hexagons in catacondensed benzenoid hydrocarbons

Boris Furtula, Ivan Gutman* & Nedžad Turković

 

The concept of electron content (EC) of hexagons in benzenoid hydrocarbons has been recently introduced in a series of scientific papers. In full analogy to it one may conceive also the energy content (ec) of hexagons. These contents are mutually related, but not in a manner that could be anticipated. On the basis of the EC- and ec-values calculated for a large number of catacondensed benzenoid hydrocarbons we establish the actual relation between these quantities. Within hexagons of the same type (terminal, linearly annelated, angularly annelated, and branched) the relation between ec and EC is nearly linear and the respective regression lines are nearly parallel and equidistant.

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 13-17

 

Relation between electron and energy contents of hexagons in pericondensed benzenoid hydrocarbons

Ivan Gutman*, Svetlana Milosavljević, Boris Furtula & Nataša Cmiljanović

 

Relations are established between the π-electron content (EC) and the π-electron energy content (ec) of hexagons in pericondensed benzenoid hydrocarbons. Whereas in catacondensed benzenoids only four types of differently annelated hexagons need to be distinguished [Furtula, Gutman & Turković, Indian J Chem 43A (2004)], in pericondensed systems there are 12 different annelation types. We show that within each of the 12 classes of equally annelated hexagons there exists a linear correlation between EC and ec. These correlations can be explained by means of the Cruickshank-Sparks equations, which relate the Pauling and Coulson bond orders. In addition, within each annelation class there is a correlation between the ec-value of a hexagon and the effect ef of the same hexagon on the total π-electron energy of the corresponding benzenoid molecule. Most of these latter correlations are curvilinear. Our main conclusions are that (a) ec is proportional to EC and (b) ec is proportional to ef, but (c) the mode of the annelation of the respective hexagon strongly influences the actual form of these interdependencies.

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 18-26

 

Synthesis, crystal structure and DNA hydrolysis activity of ternary (N-salicylidene-l-methioninato) copper(II) complexes of heterocyclic bases

Rabindranath Pradhan, Anitha M Thomas, Arindam Mukherjee, Shanta Dhar, Munirathinam Nethaji & Akhil R Chakravarty*

 

Copper(II) complexes of different nuclearities, viz. [Cu(salmet)(bpy)] (1), [Cu(salmet)(HIm)]2 (2) and [Cu(salmet)(1-MeIm)]Ą (3), where salmet is dianionic Schiff base N-salicylidene-l-methioninato, are prepared, structurally characterized by X-ray crystallography and their hydrolytic DNA cleavage activity studied (bpy, 2,2´-bipyridine; HIm, imidazole; 1-MeIm, 1-methylimidazole). Complex 1 has a square pyramidal (4 + 1) CuN3O2 coordination geometry in which the ONO-donor Schiff base occupies the basal plane and the bpy is bonded at the axial-equatorial sites. Complex 2 is a binuclear species in which two {Cu(salmet)(HIm)} moieties are covalently linked through two phenoxo oxygen atoms forming a {Cu2(m-OR)2} unit with a CuN2O3 square pyramidal (4 + 1) coordination geometry for the metal. The NH hydrogen atom of the imidazole and the unbound carboxylate oxygen atom are involved in hydrogen bonding interactions to form a supramolecular structure. Complex 3 is a 1D-chain polymeric species in which the {Cu(salmet)(1-MeIm)} units are covalently linked at the elongated axial site of the CuN2O3 coordination geometry. The pendant –SMe moiety of the Schiff base does not show any interaction with the metal ion in these structures. Complexes 1-3, having salmet displaying three different binding modes, are one-electron paramagnetic per copper. The complexes show significant DNA cleavage activity in dark giving an order: 1 > 3 > 2. The hydrolytic nature of the DNA cleavage is evidenced from the control experiments showing no apparent inhibition of cleavage under argon atmosphere and in the presence of hydroxyl radical inhibitor DMSO or singlet oxygen quencher azide ion.

IPC Code: Int. Cl.7 C07F 1/08; C07C 251/02

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 27-33

 

Dynamic processes of H-atom site exchange in trans dihydrogen hydride complex of ruthenium

V Sivakumar & Balaji R Jagirdar*

 

A new dihydrogen hydride complex of ruthenium of the type trans-[(dppm)Ru(H)(h2-H2)(PPh3)2][BF4] (1) (dppm = Ph2PCH2PPh2) has been prepared by protonating the precursor dihydride complex cis-[(dppm)Ru(H)2(PPh3)2] using HBF4.Et2O. The formulation of (1) as a dihydrogen complex has been based upon the variable temperature T1 measurements (T1(min) = 12.4 ms at 273 K, ClCD2CD2Cl, 400 MHz) and the observation of a substantial H-D coupling constant (J(H,D) = 32 Hz, 243 K, ClCD2CD2Cl) for the corresponding HD isotopomer trans-[(dppm)Ru(H)(h2-HD)(PPh3)2][BF4]. The T1 and the H-D coupling constant measurements have been carried out in the temperature range 243 – 283 K. The dihydrogen and the hydride ligands of (1) show dynamic behavior and undergo rapid H-atom site exchange at 343 K. At 273 K (1) shows a static structure. The dynamics of (1) involving a trihydride intermediate has been studied by variable temperature NMR spectroscopy. The barrier to site exchange of the H-atom between the dihydrogen with the hydride (DG) has been determined to be 14.4 kcal/mol at 303 K. Compound (1) has been found to be stable up to 343 K in solution and no loss of the H2 ligand has been observed at that temperature; in addition, the compound is stable in solution at room temperature for a period of two days.

IPC Code: Int Cl7. C07F 15/00

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 34-48

 

Influence of cerium precursor on the size and solid solubility of transition metals in combustion synthesized Ce1-xMxO2-d (M = Cu, Pd) nano crystallites: Enhancement of redox properties and catalytic activity

Arup Gayen, Tinku Baidya, A S Prakash, N Ravishankar & M S Hegde*

 

Two cerium precursors have been employed to synthesize Ce1-xMxO2-d (M = Cu, Pd) nano-crystalline catalysts by solution combustion method. These nano materials have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and BET surface area measurement. Redox behaviour of the catalysts was investigated by temperature-programmed reduction (H2 TPR). Use of ceric ammonium nitrate (precursor A) gives ceria crystallites of size 30-45 nm while cerrous nitrate (precursor B) gives 10-15 nm sized crystallites indicating three fold decrease in crystallite size of CeO2. Solid solubility of copper in CeO2 matrix is between 5-10 atom % with precursor A and it increases to 10-15 atom % with precursor B. The crystallite size is between 15-20 nm using B precursor compared to 40-50 nm crystallites with precursor A when Pd was substituted for Ce indicating approximately a two-fold decrease. With precursor A, solid solubility of Pd in ceria is between 3-5 atom % which increases to ~10 atom % with precursor B. Structural study shows M2+ ion substitution into CeO2 matrix. The enhancement of solid solubility coupled with the decrease in crystallite size is associated with an increase in oxygen storage capacity and catalytic activity for CO oxidation by O2 and NO reduction by CO. Such an approach to synthesis of transition metal ion substituted nano CeO2 is leading to catalysts with higher catalytic activity.

IPC Code: Int. Cl.7 B01J 23/00; C01F 17/00; C01G 3/02; C01G 55/00.

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 49-57

 

Competitive energy dynamics in IRMPD of UF6

Sisir K Sarkar

 

The photochemical isotope separation schemes have renewed the detailed investigations of gas phase photophysics and photochemistry of UF6 . One of the schemes is based on massive multiphoton excitation of UF6 using one or more suitable IR laser frequency in 16mm region in its ground electronic state. In the present work we have modelled such Infrared Multiphoton Dissociation (IRMPD) on a rate equation formalism. Using RRKM theory, the multiphoton dissociation rate constants for UF6 with 16 mm laser have been estimated. It is shown that about 50 laser photons, which are 15 photons excess over the dissociation threshold of 3 eV, are required for dissociation of each UF6 molecule. Using the present model, the fluence dependence of dissociation yield has been evaluated and it is found that MPD of UF6 occurs with a threshold fluence of 1 – 1.2 J cm-2. Isotopic selectivity in this model is described as the difference in the rate of laser energy absorption for the two isotopic species. Considering various time scales involving excitation, collisional deactivation and life time of energized 235-UF6  molecule, the extent of selectivity loss has been estimated.

IPC Code: Int Cl.7 C01G 43/06

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 58-63

 

Microstructure characterization of poly(2-N-carbazolylethyl acrylate) by two-dimensional NMR spectroscopy

A S  Brar*, M Markanday & S Gandhi

 

Poly(2-N-carbazolylethyl acrylate) has been synthesized by solution polymerization of 2-N-carbazolyethyl acrylate with 2,2˘-azobisisobutyronitrile as free radical initiator. Distortionless Enhancement by Polarization Transfer has been used to distinguish between the overlapping main-chain methine and side-chain methylene resonances in 13C{1H} NMR spectrum. Configurational assignments of carbon and proton resonances of main-chain methylene group have been done using two-dimensional Heteronuclear Single Quantum Correlation spectroscopy and two-dimensional Total Correlation Spectroscopy. Two and three bond order carbon/proton couplings have been investigated using Heteronuclear Multiple Bond Correlation studies.

IPC Code: Int. Cl.7: C08F 120/18; G01R 33/20

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 64-66

 

Artificial neural network aided design of a multi-component catalyst for the steam reforming of methanol

 Sh Jooya & F Gobal*

 

A neural network based on the feed forward back propagation error has been developed for the design and simulation of the catalytic properties of a multi-component system based on Cu-M-Al2O3 (M=Zn,Cr,Zr) for the steam reforming of methanol. Due to the limited size of the data set, cross validation method has to be used to enhance and also evaluate the prediction ability of the network. The best structural organization has been found to include 4,3,6,3 nodes in the input, two hidden layers and the output layer respectively.

 

IPC Code: Int. Cl.7 B01J 23/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 67-70

 

Study on lyotropic liquid crystals of the 3-octyloxy-2-hydroxypropyl trimethyl ammonium bromide-n-hexanol-water system

 Bao-Lin Yin, Xi-Lian Wei, Qing Sang & De-Zhi Sun*

 

Phase diagram of ternary system for 3-octyloxy-2-hydroxypropyl trimethyl ammonium bromide (R8TAB)-n-hexanol-water has been investigated using turbidity titration method at 25°C. Typical lyotropic liquid crystals (LLCs) of lamellar, hexagonal and cubic phases have been found in the system. The structure and the structure conversion have been determined using polarizing-light microscope, 2H nuclear magnetic resonance (2H NMR) and differential scanning calorimetry (DSC). Experimental results show that with the enhancement of relative amount of water in a mixture maintaining mass ratio of R8TAB to C6H13OH at 3:2, the phase transition is as follows: from mixed lamellar and hexagonal liquid crystals to mixed lamellar, hexagonal and cubic ones, then to single cubic one and finally to mixed hexagonal one and isotropic liquid phase.

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 71-75

 

Os(VIII) – catalysis on the oxidation of some diaryl sulphoxides with bromamine-B in alkaline medium

 Subbiah Meenakshisundaram* & Ramakrishnan Markkandan

 

The effect of substituents reveals the electronic character of Os(VIII)- catalysed N-bromobenzene sulphonamide (bromamine-B) oxidation of some diaryl sulphoxides to sulphones in a strongly alkaline (pH~11.5) t-butanol-water (1:1 v/v) medium and the conversion appears to be nucleophilic for bromamine-B (BAB). High dielectric constant of the medium favours the reactivity. The kinetic studies reveal that electron-withdrawing groups enhance the reactivity while electron-releasing ones inhibit the rate. It appears that the anion RNBr- is the reactive species of bromamine-B. The possibility of the formation of Os(VI)-BAB complex causing a retarding effect on the pseudo-first-order rate coefficients is discussed. Contrary to expectations there is a marked depression in the catalytic activity of Os(VIII) in the presence of other transition metals and pyridine bases such as 2, 2'-bipyridyl and 1,10-phenanthroline. The probable reaction mechanisms are discussed on the basis of above results.

IPC Code: Int. Cl.7 C07B 33/00; C 01G 55/00; B 01J 8/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 76-79

 

Oxygenation reactions of cobalt(II) tetraen chelates generated on flash photolysis and continuous photolysis of cobalt(III) complexes in different solvents

Chelli Janardhana*, S Jagadeeswara Rao, V Venkatesh, J Sai Kiran & R Sai Sathish

 

Photolysis of ([Co(tetraen)Cl](ClO4)2 and [Co(tetraen)NO2]-(ClO4)2 chelates in 0.1 M aq HClO4, methanol and acetonitrile media yields cobalt(II) chelates. Oxygenation reactions of cobalt(II) bound to tetraen, {N-(2-aminoethyl)-N1-[2-[(2-aminoethyl)amino]ethyl]-1,2-ethanediamine} have been studied by continuous and flash photolysis techniques. Quantum yields and excited state deactivation pathways for cobalt(III) – amine complexes have been investigated and a scheme for the excited state processes suggested. A comparison of the quantum yields in different solvent media indicates the role of solvent on the quantum yield for the photoredox process.

 

IPC Code: Int. Cl.7 C07F 15/06

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 80-84

 

Kinetics of Ru(III) catalysed oxidation of phenethyl alcohol and para-substituted phenethyl alcohols by Ce(IV) in aqueous nitric acid medium

N Vijaya Bhaskar Rao & M Anand Rao*

 

A simple, rapid and sensitive spectroscopic method for the kinetics of Ru(III) catalysed oxidation of phenthyl alcohol(PA) by Ce(IV) in aqueous nitric acid medium has been reported under varying conditions. The reaction is followed spectrophoto-metrically by measuring the decrease in absorbance of Ce(IV) at 350 nm. The rates show first order dependence on [Ce(IV)] and the rate constants evaluated at different [Ce(IV)] are found to be almost the same. Increase in [Ru(III)] has linear relation with the rate of oxidation and order in [Ru(III)] has been found to be fractional. Variation in ionic strength of the medium has significant effect on the rate of reaction. The rates of the reaction have been measured at different temperatures and the activation parameters for all the substrates computed. The rates decrease in the order – OCH3> -CH3 > -H>-Cl>-NO2 of para substituted phenethyl alcohols. Hammett’s plot of log kobs versus σ is found to be valid. The correlation between enthalapies and free energies of activation is reasonably linear with an isokinetic temperature of 425K.The rate constant k obeys corresponding equation, k=Q.e-DE#/RT.eDS#/R . Ea increases with introduction of electron- withdrawing groups into the benzene ring. The introduction of electron-releasing groups lowers the Ea for the reaction. Similarly, logA decreases with substitution of electron- withdrawing groups and increases with substitution of electron- releasing groups. A plausible mechanism consistent with the experimental results has been proposed.

IPC Code: Int. Cl.7 C 07B 33/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 85-89

 

Synthesis and characterization of some new Cu(II) complexes of azo dyes derived from 1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one

M L Harikumaran Nair*, George Mathew & M R Sudarsana Kumar

 

Some novel complexes of the ligands 1,2-dihydro-1,5-dimethyl-2-phenyl-4-(2-hydroxy-5-methyl phenylazo)-3H-pyra-zol-3-one (CAAPH) and 1,2-dihydro-1,5-dimethyl-2-phenyl-4-(2-hydroxy-5-chlorophenylazo)-3H-pyrazol-3-one (CPAAPH) with Cu(II) having the formulae [Cu(LH)Cl2], [CuLH(Ac)2], [CuLH(NO3)2], [CuLH(SO4)], [CuLH(ClO4)2], [CuLH(NCS)Cl] and [Cu(L'H)Cl2], [CuL'H(Ac)2], [CuL'-(NO3)2], [CuL'H(SO4)], [CuL'H(ClO4)2], [CuL'H(NCS)Cl] (LH=CAAPH and L'H=CPAAPH) have been synthesized and characterized by elemental analysis, IR, electronic, ESR, NMR, magnetic, conductance measurements and cyclic voltammetric studies. The ligands are found to behave in a neutral bidentate manner. All the complexes are non-electrolytes and square planar with magnetic moment ranging from 1.79 to 1.88 B.M. The X-band ESR spectra of the complexes [Cu(CAAPH)Cl2], [Cu(CAAPH)-(Ac)2], [Cu(CAAPH)(NO3)2], [Cu(CAAPH)(SO4)], [Cu(CPAAPH)(ClO4)2] and [Cu(CPAAPH)(NCS)Cl] are seen to be characteristic of Cu(II) in the ligand field with axial symmetry. The complexes [Cu (CAAPH)(SO4)] and [Cu(CPAAPH)Cl2)] are found to be orthorhombic with the unit cell dimensions such as a=5.8564 Ĺ, b=9.4817 Ĺ and c=12.8383 Ĺ; and a=5.3029 Ĺ, b=10.2028 Ĺ and c=11.6127 Ĺ, respectively. The cyclic voltammograms of [Cu(CAAPH)Cl2] and [Cu(CPAAPH)(ClO4)2] show quasi-reversible peaks which indicates that metal-ligand linkage is more covalent in nature29.

IPC Code: Int. Cl.7 C07F 1/08

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp 90-93

 

Mixed ligand triphenylphosphine/arsine Schiff base complexes of ruthenium(II) and their catalytic activities towards oxidation of alcohols

P Viswanathamurthi, A Geetha, R Karvembu & K Natarajan*

 

Mixed ligand ruthenium(II) complexes [Ru(CO)(Y)(L)], where Y = PPh3, AsPh3, pyridine (py) or piperidine (pip) and H2L = Schiff bases derived from the condensation of o-aminophenol, o-aminothiophenol and anthranillic acid with acetylacetone in 2:1 molar ratio, obtained from the reactions of [RuHX(CO)(EPh3)2(Y)] (X = H or Cl; E = P or As) with H2L, have been found to show catalytic activity in the oxidation of alcohols to aldehydes.

IPC Code: Int Cl.7 C07F 15/00; C07C 251/02

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 94-97

 

Synthesis, characterization and solid state structural studies of oxovanadium (IV) – O, N donor Schiff base chelates

A P  Mishra* & L R Pandey

 

VO(IV)-complexes with the Schiff bases viz., 4-chlorobenzylidene-2-amino-4-chlorophenol (CAP), 4-dimethyl-aminobenzylidene-2-aminophenol (DAP) and 2-hydroxy-1-naphthylidene-4-bromoaniline (HBA) have been synthesized and characterized by elemental analyses, molar conductance, electronic spectra, FT-IR, 1H-NMR, ESR, FAB mass, thermal and magnetic susceptibility measurements. FAB mass and thermal data show degradation of complexes. Synthesized complexes have been tested for their reactivity and substitution behaviour. All the three ligands behave as bidentate coordinating through O and N donor. The proposed geometry for the complexes is square pyramidal. X-ray powder diffraction data show that two complexes are crystallized in tetragonal system. Solid state AC electrical conductivity studies reflect semiconducting behaviour of complexes.

IPC Code: Int. Cl.7 C07F 9/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, January 2005, pp. 98-101

 

Determination of small quantities of nicotinic acid in presence of nicotinamide by modified Konig reaction

Seemab Khan, M K Rai*, V K Gupta & J K Rai

 

A modified sensitive spectrophotometric method for the determination of nicotinic acid and nicotinamide in sub-microgram levels is described. During their reaction with cynogen bromide, the pyridine rings are split by the Konig reaction and the reaction products are coupled with diazotised, p-aminoacetophenone, p-aminobenzoic acid, sulphanilic acid and H-acid to form coloured azo dyes. The colour system obeys Beers law over the concentration range of 0.008-0.08 ppm, 0.02-0.16 ppm, 0.04-0.36 ppm and 0.05-0.4 ppm for nicotinic acid respectively. Similarly, the colour system obeys Beers law over the concentration range of 0.02– 0.2 ppm, 0.04-0.4 ppm, 0.05-0.56 ppm and 0.07-0.6 ppm for nicotinamide using PAAP, PABA, sulphanilic acid and H-acid respectively. p-Aminoacetophenone gives the best result for the determination of nicotinic acid/nicotinamide. The sensitivity of the method after this modification is found to be about eight times more than that of the conventional Konig reaction. The method is free from interference of common diverse ion and has been satisfactorily applied to the determination of nicotinic acid in presence of nicotinamide in food, blood, urine and pharmaceuticals.

IPC Code: Int. Cl.7. G01N 21/00