Indian Journal of Chemistry

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

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

 

 

 

 

 

VOLUME 51A

NUMBER 11

NOVEMBER 2012

 

CONTENTS

 

 

1529

 

Effect of interaction between CuO and CeO2 on the performance of CuO-CeO2 catalysts for selective oxidation of CO in H2-rich streams

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pengfei Zhu, Mei Liu & Renxian Zhou *

 

 

 

Due to strong interaction and synergism between interfacial
CuO and CeO2
, Hy-CuO-CeO2 catalyst prepared by hydrothermal method exhibits the highest catalytic activity, particularly at low temperatures.

 

 

 

 

1538

 

Synthesis and optical properties of pure CdTiO3 and Ni2+ and Zn2+ ion substituted CdTiO3 obtained by a novel precursor route

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mamta Kharkwal, S Uma & R Nagarajan*

 

 

 

In ilmenite and perovskite forms of CdTiO3 synthesized from oxinate precursors, phase transition from ilmenite to perovskite structure occurs at 1000 °C. Ni2+ and Zn2+ substituted CdTiO3 show a shift in the optical bands to red and blue regions with respect to pure CdTiO3.

 

 

 

 

1545

 

Primary amine-based palladium(II) complexes as catalysts for Suzuki-Miyaura reaction: Experimental and theoretical investigations on the effects of substituents on nitrogen atom

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Archana Tairai, Pradip K Bhattacharyya, Rahul Kar & Pankaj Das*

 

 

 

Catalytic activities of eight primary amine-based palladium complexes are explored for Suzuki-Miyaura reactions of aryl halides with arylboronic acids in water at room temperature. The observed catalytic trend correlates well with the DFT-based reactivity descriptors such as chemical hardness, chemical potential and electrophilicity index of the ligands.

 

 

 

 

 

 

1553

 

A DFT study on the mechanism of the gas phase reaction of niobium with acetaldehyde

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Yong Wang & Gui-hua Chen*

 

 

 

The spin-forbidden reaction, 6Nb+CH3CHO → CP1→ 4IM1→ 4TS15→ CP2→ 2IM5→ 2TS59 2IM9, is found to be energetically most favorable. The identified reaction mechanisms suggest sextet–quartet and quartet–doublet surface crossings. The crossing region has been determined approximately.

 

 

 

 

 

 

 

Notes

 

1561

 

Fluorescence and CD studies of protein denaturation in the presence of sub-picomolar gold nanoparticles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K Ojha, P K Chowdhury & A K Ganguli*

 

 

 

Sub-nanomolar concentrations of gold nanoparticles are found to have some visible effects on the conformation of BSA. A small but definite enhancement in the trp emission in presence of
sub-picomolar gold nanoparticles is observed.

 

 

 

 

 

 

 

 

1567

 

Flow injection preconcentration system using a new functionalized resin for determination of cadmium(II) by flame atomic absorption spectroscopy

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reena Saxena* & Suneeti Singh

 

 

 

A rapid, sensitive and selective online preconcentration procedure for the determination of cadmium(II) in industrial water samples by flow injection technique with flame atomic absorption spectroscopy as a detection method is reported. The method is linear over the concentration range of 0–120 µg L-1 Cd(II). The limits of detection are 1.038 and 0.57 µg L-1 for 60 s and 120 s sorption times respectively. The precision for 5 replicate measurements are 1.68 and 1.12 for the determination of 20 and 50 µg L-1 Cd(II) respectively.

 

 

 

1574

 

Kinetics and mechanism of oxidation of tyrosine by vanadium(V) in aqueous hydrochloric and ethanoic acid medium

 

 

 

 

 

 

 

 

 

 

 

 

 

A S Onkar, P N Naik, S D Gunagi, S T Nandibewoor & S A Chimatadar*

 

 

 

In aqueous hydrochloric and ethanoic acid media, vanadium(V)
is reduced to vanadium(IV) and tyrosine is oxidized to
4-hydroxyphenyl acetaldehyde. The reaction is first order with respect to vanadium(V) and less than unit order with respect to tyrosine concentrations. The reaction follows the rate law:
Rate =-d[VO2+]/dt  

 

 

 

1580

 

Corrigendum

 

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1529-1537

 

 

Effect of interaction between CuO and CeO2 on the performance of CuO-CeO2 catalysts for selective oxidation of CO in H2-rich streams

Pengfei Zhua, Mei Liu a & Renxian Zhoub, *

aSchool of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China

bInstitute of Catalysis, Zhejiang University, Hangzhou 310028, PR China

Email: zhourenxian@zju.edu.cn

Received 4 July 2012; revised and accepted 27 September 2012

A series of CuO–CeO2 catalysts have been prepared by different methods and the effects of interaction between CuO and CeO2 on the performance of CuO-CeO2 catalysts for selective oxidation of CO in H2-rich streams have been investigated. The results show that HY-CuO-CeO2 with strong interaction and synergistic effect between interfacial CuO and CeO2 exhibits superior catalytic activity, especially at low temperatures. For HY-CuO-CeO2, the temperature of 50 % CO conversion is only 75 °C and the temperature window of CO conversions up to 99.0 % is about 30 oC wide, from 120140 °C. The strong interaction between copper and cerium oxide promotes the reduction of highly dispersed CuO species, the formation and stability of abundant Cu+ species and the production of abundant oxygen vacancies and lattice oxygen of copper oxide.

Keywords: Catalysts, Ceria, Cupric oxide, Selective oxidation, Carbon monoxide oxidation, Oxidation

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1538-1544

 

 

Synthesis and optical properties of pure CdTiO3 and Ni2+ and Zn2+ ion substituted CdTiO3 obtained by a novel precursor route

Mamta Kharkwal, S Uma & R Nagarajan*

Materials Chemistry Group, Department of Chemistry, University of Delhi, Delhi 110 007, India
Email: rnagarajan@chemistry.du.ac.in

Received 14 July 2012; revised and accepted 27 September 2012

Monophasic CdTiO3 in ilmenite and perovskite structures have been synthesized by a novel precursor route using oxine as the complexing agent and their optical and photoluminescence properties have been characterized. The co-precipitated oxinates of cadmium and titanium on one time heating at 600 °C for 6 h yields the ilmenite structured CdTiO3 (space group R ) with the lattice parameters a = 5.237(1) and c = 14.84 (6) Ĺ as revealed by its powder X-ray diffraction pattern. The presence of rhombohedral symmetry is further confirmed by the six bands observed at 216, 246, 325, 461, 598, and 694 cm-1 due to Eg and Ag modes in the Raman spectroscopy. Phase transition from ilmenite to perovskite structure (space group Pbnm) occurs at 1000 °C. PXRD pattern of the transformed CdTiO3 is indexed in the orthorhombic symmetry with a = 5.305 (3); b = 5.421 (1); c = 7.617 (3) Ĺ. The broadness and the shift of the Raman band position to 279, 326, 400, 444 and 578 cm-1 endorses the orthorhombic symmetry. From the diffuse reflectance measurements, band gap values of 2.9 eV and 2.8 eV have been estimated for the ilmenite and perovskite forms of CdTiO3. An additional emission band at 3.21 eV is observed in the photoluminescence spectrum of ilmenite CdTiO3. Synthesis and optical properties of Ni2+ and Zn2+ substituted CdTiO3 are also reported.

Keywords: Ilmenites, Perovskites, Titanates, Cadmium, Titanium, Oxine, Photoluminescence

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1545-1552

 

 

Primary amine-based palladium(II) complexes as catalysts for Suzuki-Miyaura reaction: Experimental and theoretical investigations on the effects of substituents on nitrogen atom

Archana Tairaia, Pradip K Bhattacharyya b, Rahul Kara & Pankaj Dasa, c, *

aDepartment of Chemistry, Dibrugarh University, Dibrugarh 786 004, Assam, India

Email: pankajd29@yahoo.com

bDepartment of Chemistry, Arya Vidyapeeth College, Guwahati 781 016, Assam, India

cDepartment of Chemistry, Rajiv Gandhi University, Doimukh, Rono Hills, Itanagar 791 112, Arunachal Pradesh, India

Received 9 November 2011; revised and accepted 27 September 2012

Catalytic efficiencies of eight primary amine-based palladium(II) complexes of general formula, trans-[PdCl2(RNH2)2] (1L1-L8), have been evaluated for the Suzuki-Miyaura reaction of 4-bromonitrobenzene with phenylboronic acid at room temperature in water. The efficiencies of the catalysts follow the order: Ph3CNH2 (L8) > Ph2CHNH2 (L7) > Ph2CH2NH2 (L6) > tBuNH2 (L4) > CyNH2 (L5) > iPrNH2 (L2) > nBuNH2 (L3) > nPrNH2 (L1). In order to ascertain the parameters affecting catalytic efficiencies, DFT based reactivity descriptors have been analyzed for the ligands. Good linear correlation is obtained between the observed yield (%) and the gas phase reactivity descriptors (chemical hardness, chemical potential and electrophilicity index). Good-to-excellent yields of coupling products are achieved using the 1L8 complex as the catalyst for a range of aryl halides.

Keywords: Density functional calculations, Catalysts, Suzuki-Miyaura reactions, Cross coupling reactions, Palladium, Amine- based ligands

 

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1553-1560

 

 

A DFT study on the mechanism of the gas phase reaction of niobium with acetaldehyde

Yong Wanga, b & Gui-hua Chena, *

aSchool of Pharmaceutical and Chemical Engineering, Taizhou University, Linhai 317000, PR China

bCollege of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, PR China

Email: chenguihua518@hotmail.com

Received 5 July 2012; revised and accepted 10 October 2012

The reaction between niobium atom and acetaldehyde has been investigated with a DFT approach. Both ground and excited state potential energy surfaces are investigated in detail. The present results show that the title reaction starts with the formation of a η2-CH3CHO-metal complex followed by C−C, aldehyde C−H, methyl C−H and C−O bond activation. These reactions can lead to several different products, viz., NbCO+CH4, NbCOCH2+H2, NbCOCH3+H, NbCHO CH2+H, NbH+CH3CO, NbO+CH3CH and NbO+C2H4. The spin-forbidden reaction, 6Nb+CH3CHO → 2IM9 is found to be energetically most favorable. According to the identified reaction mechanisms, the sextet–quartet and quartet–doublet surface crossings are suggested and the crossing region is approximately determined. The present results may be helpful in understanding the mechanism of the title reaction and in experimental investigations of the reaction.

Keywords: Theoretical chemistry, Density functional calculations, Potential energy surfaces, Niobium, Acetaldehyde

 

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1561-1566

 

 

Fluorescence and CD studies of protein denaturation in the presence of sub-picomolar gold nanoparticles

K Ojha, P K Chowdhury & A K Ganguli*

Department of Chemistry, Indian Institute of Technology, Delhi, New Delhi 110 016, India

Email: ashok@chemistry.iitd.ac.in

Received 27 July 2012; revised and accepted 4 October 2012

The dependence of nanoparticle concentration on the conformation of bovine serum albumin has been studied. A very small but consistent enhancement in the tryptophan emission is observed in the presence of sub-picomolar concentration of gold nanoparticles. At this concentration, the bovine serum albumin unfolding profile in presence and absence of nanoparticles are quite similar and the protein conformation remains essentially conserved.

Keywords: Protein-nanoparticle interactions, Protein conformation, Protein denaturation, Thermal denaturation, Chemical denaturation, Nanoparticles, Gold nanoparticles, Fluorescence spectroscopy, Circular dichroism

 

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1567-1573

 

 

Flow injection preconcentration system using a new functionalized resin for determination of cadmium(II) by flame atomic absorption spectroscopy

Reena Saxena* & Suneeti Singh

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

Email: reenasax@hotmail.com

Received 12 April 2012; revised and accepted 3 October 2012

A rapid and sensitive method for the determination of trace level of Cd(II) in industrial effluents by flame atomic absorption spectroscopy has been developed. The technique is based on the online flow injection preconcentration of Cd(II) ions on a mini column, packed with Amberlite XAD-2 functionalized with xylenol orange. Flow injection variables have been optimized for the determination and quantitative preconcentration of Cd(II). Cd(II) ions are effectively retained on the mini column at pH 5.0. A high sorption capacity of 348 µmol/g of dry resin is obtained and chelating resin can be reused for 70-80 cycles of sorption desorption without any significant change in the sorption capacity. With preconcentration times of 60 s and 120 s at a sample loading flow rate of 5 mL min-1, preconcentration factors of 17 and 32 are obtained. The calibration graph using the preconcentration system for Cd(II) is linear over the concentration range of 0-120 µg L-1. The precision for 5 replicate measurements are 1.68 and 1.12 for the determination of 20 and 50 µg L-1 Cd(II) respectively. The limits of detection obtained are 1.038 and 0.57 µg L-1 for 60 s and 120 s sorption time respectively. A sample throughput of 32 h-1 is obtained with 5 mL of sample solution. Spiked recovery studies in water samples with certified Cd(II) nitrate solution traceable to NIST shows recovery in the range of 98-99 %. The accuracy of the developed online FI-FAAS procedure has been validated by analyzing cadmium(II) in standard reference material (SRM-1643e).

Keywords: Flame atomic absorption spectrometry, Online preconcentration, Amberlite XAD-2, Xylenol orange, Cadmium

 

 

Indian Journal of Chemistry

Vol. 51A, November 2012, pp. 1574-1579

 

 

Kinetics and mechanism of oxidation of tyrosine by vanadium(V) in aqueous  hydrochloric and ethanoic acid medium

 

A S Onkar, P N Naik, S D Gunagi, S T Nandibewoor & S A Chimatadar*

PG Department of Studies in Chemistry, Karnatak University, Pavate Nagar, Dharwad 580 003, India

E-mail: schimatadar@gmail.com

Received 3 May 2011; re-revised and accepted 10 October 2012

Vanadium(V) and tyrosine does not react in sulpuric acid or perchloric acid media at 25 °C. However, in aqueous hydrochloric and ethanoic acid media vanadium(V) is reduced to vanadium(IV) and tyrosine oxidized to 4-hydroxyphenyl acetaldehyde. In this reaction, two moles of vanadium(V) consume one mole of tyrosine. The reaction is first order with respect to vanadium(V) and less than unit order with respect to tyrosine concentrations. Increase in hydrochloric acid concentration increases the rate. The order with respect to acid concentration is found to be less than unity. The effect of ionic strength and dielectric constant of the medium have been studied and a suitable mechanism is proposed. The activation parameters and frequency factor have been determined on the basis of the rate law:  

Rate  =  d[VO2+]/dt