Indian Journal of Chemistry

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

CODEN: ICACEC; ISSN: 0376-4710 (Print), 0975-0975 (online)

http://www.niscair.res.in; http://nopr.niscair.res.in

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VOLUME 50A

NUMBER 5

MAY 2011

CONTENTS

 

641

 

Phase behaviour and rheological properties of
the lamellar liquid crystals formed in
dodecyl polyoxyethylene polyoxypropylene ether/water system

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J Zhao, Z N Wang*, X L Wei, F Liu, W Zhou,
X L Tang & T H Wu

 

 

 

 

The rheological properties of the lamellar liquid crystals formed in the binary system, C12E4P5/H2O, indicate that these liquid crystals exhibit shear-thinning properties and behave like a plastic material. The lamellar liquid crystals show a typical gel-like rheogram, which can be described by the Maxwell model.

 

 

 

650

 

Mechanistic studies of aquachlororhodium(III) catalysis in potassium iodate oxidation of
1,2-propanediol in acidic medium: A kinetic approach

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bharat Singh*, Aniruddh Kumar Singh &
Anamika Singh

 

 

 

 

Aquachlororhodium(III) catalysis in oxidation of 1,2-propanediol by acidic solution of KIO3 involves interaction between IO3 and [Cl5Rh(HO→Hg)]-1 in the slow and rate determining step, giving an active complex [RhCl5(IO3)]-3 which attacks 1,2-propanediol rapidly to regenerate the reactive species, Rh(III) chloride. Acetic acid and formic acid are obtained as oxidation products in the subsequent fast steps. These steps lead to the following rate law consistent with the observed kinetic results.

 

 

 

 

658

 

Oxidation of substituted alkynes catalyzed by a
non-heme iron(III) bis-benzimidazole diamide complex as catalyst under ambient conditions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ruchi Bakshi, Ravinder Kumar & Pavan Mathur*

 

 

 

 

Iron(III) complexes of N,N′-bis(2-methylbenzimidazolyl) hexanediamide have been used as catalyst in the oxidation of substituted alkynes along with TBHP or H2O2 as an alternate source of oxygen.

 

 

 

 

 

 

 

 

 

664

 

Synthesis, spectral characterization and DNA cleavage studies of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes with benzofuran-2-carbohydrazide schiff bases

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

M B Halli* & Vijayalaxmi B Patil

 

 

 

 

Metal(II) complexes have been synthesized using schiff bases derived from the condensation of benzofuran-2-carbohydrazide with 1-naphthaldehyde or 6-methoxy-2-naphthaldehyde. The Cu(II), Ni(II) and Co(II) complexes have also been studied for their plasmid (pBR322) DNA cleavage activity.

 

 

 

 

 

 

 

 

 

Notes

 

670

 

Effect of benzocyclobutadieno-annelation on cyclic conjugation

 

 

 

 

 

 

 

 

 

 

 

 

 

Ivan Gutman

 

 

 

 

 

 

 

 

674

 

Diorgano-gallium and -indium complexes with
1-(hydroxymethyl)pyrazole and 3,5-dimethyl-1-(hydroxymethyl)pyrazole: Synthesis, characterization and crystal
structures of [Me2MOCH2dmpz]2 (M = Ga, In) and [(Me2Ga)2(-OH)(-dmpz)][dmpzCH2OH]

 

 

 

 

 

 

 

Nisha P Kushwah, Manoj K Pal, Amey P Wadawale & Vimal K Jain*

 

 

 

 

 

 

 

 

 

680

 

Dielectric measurements of nematic and smectic A phases in a binary system

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rajinder K Bamezai*, Meena Sharma,
Monika Gupta, Ankush Gupta & Arti Soni

 

 

 

 

Dielectric properties of two bi-component mixtures of different polarities are presented. In the case of large concentration of highly polar group, an intermediate nematic phase has been observed. Both smectic A and nematic phases show low frequency relaxation phenomenon.

 

 

Authors for correspondence are indicated by (*)

 

 

 

 

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 641-649

 

Phase behaviour and rheological properties of the lamellar liquid crystals formed in dodecyl polyoxyethylene polyoxypropylene ether/water system

J Zhaoa, Z N Wanga, *, X L Weib, F Liuc, W Zhoua, X L Tanga & T H Wua

aCollege of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes Ministry of Education, Shandong Normal University, 250014 Jinan, China

Email: zhongniw@hotmail.com

bCollege of Chemistry and Chemical Engineering, Liaocheng University, 252059 Liaocheng, China

cTest Center, Shandong Academy of Sciences, 250014 Jinan, China

Received 26 November 2010; revised and accepted 19 April 2011

The temperature-composition phase diagram of the binary nonionic surfactant dodecyl polyoxyethylene polyoxy-propylene ether/water system has been determined from 10 C to 70 C. Two domains of lamellar liquid crystal phase are found in the binary system as the concentration of the nonionic surfactant increases. The phase boundary of the lamellar phase in the phase diagram has been identified by differential thermal analysis. The steady and dynamic rheological properties of the lamellar liquid crystals have been studied. Steady shear rheology results indicate that the lamellar liquid crystals show shear-thinning behavior, and behave as a plastic system with the m parameter between 0.6 and 0.7 in the empirical equation. s = sHB + Kgm. Dynamic rheological results show that the lamellar phase exhibits a typical gel-like rheogram. With increase in surfactant content, the dynamic modulus increases, while with increases in temperature, the dynamic modulus decreases.

Keywords: Solution chemistry, Liquid crystals, Phase behaviour, Rheological properties, Lamellar liquid crystals, Dodecyl polyoxyethylene polyoxypropylene ether

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 650-657

 

Mechanistic studies of aquachlororhodium(III) catalysis in
potassium iodate oxidation of 1,2-propanediol in acidic medium:
A kinetic approach

Bharat Singh*, Aniruddh Kumar Singh & Anamika Singh

Chemical Kinetics Laboratory, Department of Chemistry, University of Allahabad, Allahabad 211 002, India

Email: bschem_au@yahoo.com

Received 22 December 2010; revised and accepted 11 April 2011

The kinetics of homogeneously Rh(III) catalysed oxidation of 1, 2-propanediol by acidic solution of potassium iodate at constant ionic strength of the medium has been investigated at 308 K. The reaction follows complex kinetics, being first order in [KIO3], zero order in 1, 2-propanediol and inverse fractional order in both [H+] and [Cl]. The first order rate constant increases linearly with increase in [Rh(III)] in its lower concentration range but as the concentration of Rh(III) is increased towards the higher range, the rate constant becomes almost constant, indicating positive fractional order in [Rh(III)]. Variation of ionic strength of the medium and successive addition of mercuric acetate (used as I ions scavenger) has a positive effect on the rate of the reaction. IO3 and [RhCl5(H2O)]-2 have been postulated as the reactive species of KIO3 and Rh(III), respectively. Activation parameters for the slow and rate determining step of the proposed mechanism, which involves the formation of the most activated complex, [Cl5Rh(HO→Hg)], prior to the slowest step, have been obtained from rate measurements at 30, 35, 40 and 45 C. The rate law conforming to the observed kinetic results has been derived as . The main oxidation products have been identified as acetic acid and formic acid.

Keywords: Kinetics, Reaction mechanisms, Oxidation, Rhodium, Propanediol

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 658-663

 

Oxidation of substituted alkynes catalyzed by a non-heme iron(III)
bis benzimidazole diamide complex as catalyst under ambient conditions

Ruchi Bakshi, Ravinder Kumar & Pavan Mathur*

Department of Chemistry, University of Delhi, Delhi 110 007, India

Email: pavanmat@yahoo.co.in

Received 3 May 2010; re-revised and accepted 8 April 2011

Bis-benzimidazole diamide ligand, N,N′- bis(2-methylbenzimidazolyl) hexanediamide [GBHA = L], and its Fe(III) complexes have been synthesized. The Fe(III) complexes have been analyzed for the composition [Fe(L)X3].nH2O where X is an exogenous anionic ligand (X=Cl, NO3) and characterized by IR, UV-visible, cyclic voltammetry and EPR spectroscopy. Low temperature EPR spectra have been obtained for the complexes that indicate rhombic geometry environment in solution state. Oxidation of substituted alkynes has been investigated using these Fe(III) complexes as catalyst with TBHP and H2O2 as an alternate source of oxygen. The isolated products have been characterized by GC-MS.

Keywords: Coordination chemistry, Oxidation, Iron, Alkynes, Benzimidazole diamides, Amides, Benzimidazoles,

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 664-669

 

Synthesis, spectral characterization and DNA cleavage studies of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes with
benzofuran-2-carbohydrazide schiff bases

M B Halli* & Vijayalaxmi B Patil

Department of Chemistry, Gulbarga University, Gulbarga 585 106, Karnataka, India

Email: mbhalli@rediffmail.com

Received 3 August 2010; re-revised and accepted 11 April 2011

New schiff bases have been synthesized from benzofuran-2-carbohydrazide and 1-naphthaldehyde [NMBC] or 6-methoxy-2-naphthaldehyde [MNMBC]. Complexes of the type MLX2, where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), L = NMBC or MNMBC and X = Cl, have been synthesized and characterized on the basis of analytical data, IR, UV-vis, 1H NMR, DART-MS and ESR spectral data and magnetic studies. All the complexes are soluble in DMF and DMSO. The measured molar conductance values indicate that the complexes are non-electrolytic in nature. The DNA cleavage activities of the schiff bases and their Co(II), Ni(II) and Cu(II) complexes have been studied by agarose gel electrophoresis method. The Cu(II), Ni(II) and Co(II) complexes have also been studied for their plasmid (pBR322) DNA cleavage activity.

Keywords: Coordination chemistry, Benzofurans, Schiff bases, DNA cleavage, Copper, Nickel, Cobalt, Zinc, Cadmium, Mercury

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 670-673

 

Effect of benzocyclobutadieno-annelation on cyclic conjugation

Ivan Gutman

Faculty of Science, P.O. Box 60, 34000 Kragujevac, Serbia

Email: gutman@kg.ac.rs

Received 24 January 2011; accepted 1 April 2011

By extensive numerical testing it is found that two regularities for the effect of benzocyclobutadieno (BCBD) annelation on the π-electron conjugation pattern, namely, linear BCBD-annelation increases, whereas angular BCBD-annelation decreases the intensity of cyclic conjugation in a ring, relative to its value in the non-annelated parent compound, are generally applicable to benzenoid hydrocarbons, especially in the case of single BCBD-annelation. On the other hand, in non-benzenoid π-electron systems, numerous drastic violations were discovered.

 

Indian Journal of Chemistry

Vol 50A, May 2011, pp. 674-679

 

Diorgano-gallium and -indium complexes with
1-(hydroxymethyl)pyrazole and 3,5-dimethyl-1-(hydroxymethyl)pyrazole:
Synthesis, characterization and crystal structures of [Me2MOCH2dmpz]2
(M = Ga, In)
and [(Me2Ga)2(-OH)(-dmpz)][dmpzCH2OH]

Nisha P Kushwah, Manoj K Pal, Amey P Wadawale & Vimal K Jain*

Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India

Email: jainvk@barc.gov.in

Received 8 February 2011; accepted 1 April 2011

The reactions of triorgano-gallium and -indium etherate with 1-(hydroxymethyl)pyrazole and 3,5-dimethyl-1-(hydroxymethyl) pyrazole in benzene yields complexes of the type [(R2MO-CH2-(pz)-(R′)2]2 (R = Me, Et; M = Ga/In; R′ = H, Me) in nearly quantitative yields. The complex, [Me2GaOCH2dmpz]2 when recrystallized from dichloromethane in air, afforded a mixed bridged complex, [{Me2Ga}2(-OH)(-dmpz)][dmpzCH2OH], formed by hydrolysis by aerial moisture. These complexes have been characterized by elemental analysis, IR, NMR (1H and 13C{1H}). The molecular structures of [Me2MOCH2dmpz]2 (M = Ga, In) and [(Me2Ga)2(-OH)(-dmpz)][dmpzCH2OH] have been established by single crystal X-ray diffraction analyses. The analyses reveal their dimeric structures with the former two having five coordinated metal centers while the gallium atom in the latter has a distorted tetrahedral configuration.

Keywords: Coordination chemistry, Organometallic chemistry, Crystal structures, X-ray diffraction, Gallium, Indium, Pyrazoles

 

Indian Journal of Chemistry

Vol. 50A, May 2011, pp. 680-684

 

Dielectric measurements of nematic and smectic A phases in
a binary system

Rajinder K Bamezai*, Meena Sharma, Monika Gupta, Ankush Gupta & Arti Soni

Department of Chemistry, University of Jammu, Jammu 180 006, India

Email: rkb10@rediffmail.com

Received 7 December 2010; revised and accepted 11 April 2011

The phase diagram of a binary mixture of 4-n-octyloxy-phenyl4′-n-heptylcyclohexane carboxylate (molecule having weak polar terminal group) and 4-nitrophenyl-4′-n-pentylbenzoate (molecule having strong polar terminal group) has been studied using polarizing microscope and differential scanning calorimeter. The phase diagram shows an enhancement in smectic A phase over a wide composition range and intermediate nematic phase in a narrow composition range. The dielectric properties of these phases are investigated in the frequency range of 100 Hz to 1 MHz.

Keywords: Liquid crystals, Phase diagrams, Dielectric properties, Nematic phase, Smectic phase