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 51A

NUMBER 3

MARCH 2012

 

CONTENTS

 

 

411

 

Photocatalytic reduction of carbon dioxide by water on titania: Role of photophysical and structural properties

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K Rajalakshmi, V Jeyalakshmi, K R Krishnamurthy &
B Viswanathan
*

 

 

 

Photo-physical properties and activity of titania samples
(P-25, Hombikat-UV-100 and RM-TiO2) have been evaluated
for photoreduction of CO2 with water. In terms of total hydrocarbon production, P-25 displays maximum activity and yields maximum methane and methanol, while ethanol is formed in significant amounts in the case of Hombikat and RM-TiO2 but not with P-25. While the photocatalytic activity is governed by the generation and life span of photo-induced charge carriers, product selectivity appears to be determined by the coordination environment of surface Ti ions (four/five coordinated) evolved during catalyst preparation.

 

 

420

 

Selective oxidation of cyclohexane to KA-oil with oxygen over active Co3O4 in a solvent-free system

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X-H Lu, H-X Yuan, J Lei, J-L Zhang, A-A Yu, D Zhou & Q-H Xia*

 

 

 

Heterogeneous oxidation of liquid cyclohexane with molecular oxygen to KA-oil has been carried out in a solvent-free system. The catalytic activity of the active Co3O4 catalyst, prepared by simple calcination at 550 °C, is comparable to that of Co3O4 nanocrystals and Co/ZSM-5.

 

 

 

 

 

 
428
 
Photocatalytic degradation of an azo dye, Acid Red 27,
in aqueous solution using nano ZnO
 
 
 
 

 

 

 

 

 

 

 

 

M Shanthi* & V Kuzhalosai
 

 

 

 

 

 

 

 

435

 

A new calcium(II) coordination polymer based on a
µ2-bridging tridentate 4-nitrobenzoate

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bikshandarkoil R Srinivasan*, Santosh Y Shetgaonkar, Manav Saxena & Christian Näther

 

 

 

The synthesis and structural characterization of a new calcium(II) coordination polymer, [[Ca(H2O)2(4-nba)2]·2dmp]n, based on a
μ2-bridging tridentate 4-nba ligand is described.

 

 

 

 

 

 

444

 

Coordination chemistry of the multi-funtionalized
3-(diphenylphosphino)-1-propylamine ligand with ruthenium(II)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Geetika Borah* & Devajani Boruah

 

 

 

Synthesis and characterization of two neutral and two cationic complexes of Ru(II) with 3-diphenylphosphino-1-propylamine ligand are reported. The neutral complexes exhibit good catalytic activity toward the oxidation of aromatic alcohols.

 

 

 

 

Notes

 

453

 

Copper(II) complexes with ONS donor ligand and triphenylphosphine: Synthesis, characterization and catalytic applications

 

 

 

 

 

 

 

 

 

 

 

 

 

 

S Priyarega, M Muthu Tamizh, S Ganesh Babu,
R Karvembu & K Natarajan
*

 

 

 

Copper(II) complexes of the general formula [Cu(L)(PPh3)]
(H2L = bifunctional tridentate ONS donor Schiff base ligand) have been prepared and characterized by UV-vis, IR and EPR spectroscopy. Redox behavior of the complexes has been examined by cyclic voltammetry. The Cu(II) complexes act as  catalysts for the N-arylation of imidazole.

 

 

 

 

 

 

458

 

 

Synergetic influence of mercaptoacetic acid on the reaction of thiourea with methylene blue in acidic medium

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K K Mishra* & Upasana Dwivedi

 

 

 

Mercaptoacetic acid considerably enhances the rate of thiourea- methylene blue reaction in acidic medium due to synergetic effect. ESI-MS and 1H-NMR spectra show the formation of a persulphide-like species, which perhaps causes the synergetic effect.

 

 

                                      

 

 

 

465

 

Guide to Authors

 

 

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

 

 

 

 

 

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 411-419

 

Photocatalytic reduction of carbon dioxide by water on titania:
Role of photophysical and structural properties

K Rajalakshmi, V Jeyalakshmi, K R Krishnamurthy & B Viswanathan*

National Centre for Catalysis Research (NCCR), Indian Institute of Technology Madras,
Chennai 600 036, Tamil Nadu, India
Email: bvnathan@iitm.ac.in

Received 1 November 2011; revised and accepted 13 January 2012

 

Photocatalytic reduction of carbon dioxide has been investigated on three different titania catalysts (two commercial titania, De Gussa P-25 and UV-100 Hombikat and another catalyst prepared by sol-gel method under reverse micelle environment) dispersed in aqueous alkaline medium under irradiation in visible region (300-700 nm) from Hg lamp. The catalysts have been characterized by XRD, diffuse reflectance and fluorescence spectroscopic techniques and textural analysis. Methane, methanol and ethanol are observed as the major products. Activity in terms of total hydrocarbons production and (methane + methanol) yields during six hours run follows the order: P-25>RM-TiO2>UV-100. Ethanol is formed in significant amounts in the case of UV-100 and RM-TiO2 but not with P-25. Probable reaction pathways that lead to the formation of these products have been proposed. While the catalytic activity is governed by the generation and life span of photo-induced charge carriers, it is envisaged that product selectivity is determined by the type of transformations that the transient surface species undergo on titania. Surface Ti ions with singly or doubly vacant coordination sites (four or five coordinate Ti ions) act as active centres for these transformations. The relative population of four/five coordinate Ti ions play a vital role in directing the transformations and hence selectivity. The coordination environment of surface Ti atoms evolves during catalyst preparation. Photophysical as well as structural properties of titania samples influence their overall catalyst performance.

Keywords: Photocatalytic reduction, Photophysical properties, Titania, Carbon dioxide reduction, Structural properties

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 420-427

 

Selective oxidation of cyclohexane to KA-oil with oxygen over active Co3O4 in a solvent-free system

X-H Lu, H-X Yuan, J Lei, J-L Zhang, A-A Yu, D Zhou & Q-H Xia*

Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
and School of Chemistry and Chemical Engineering, Hubei University,
Wuhan 430062, PR China

Email: xiaqh518@yahoo.com.cn

Received 9 July 2011; revised and accepted 16 January 2012

Heterogeneous oxidation of liquid cyclohexane with molecular oxygen was carried out in a solvent-free system initiated by various catalysts and additives. Among those catalysts tested, the Co3O4 catalyst prepared by a simple calcination at 550 °C was relatively active for the oxidation of cyclohexane to KA-oil (a mixture of cyclohexanone and cyclohexanol), and could achieve about 9.2 mol% conversion of cyclohexane and 92.7 % selectivity of KA-oil at 130 °C under the pressure of 1.0 MPa O2 for 2 h, comparable to those of Co3O4 nanocrystals and Co/ZSM-5. This would help to widen the scope of the catalysts available for the titled oxidation. The use of peroxides and NHPI as the initiators without any catalyst could lead to the occurrence of non-catalytic oxidation of cyclohexane as well.

Keywords: Catalysis, Heterogeneous catalysis, Cobalt oxide, Solvent-free catalytic systems

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 428-434

 

Photocatalytic degradation of an azo dye, Acid Red 27,
in aqueous solution using nano ZnO

M Shanthi* & V Kuzhalosai

Department of Chemistry, Annamalai University, Annamalainagar 608 002, India

Email: shanthimsm@gmail.com

Received 6 May 2011; revised and accepted 20 December 2011

Photocatalytic degradation of Acid Red 27 by nano ZnO has been investigated under different conditions. Optimum experimental conditions on catalyst amount, pH and dye concentration have been determined. Addition of some inorganic oxidizing species such as H2O2, K2S2O8 and KBrO3 up to a certain concentration increases the rate of degradation. The photodecolourisation and degradation kinetics are discussed in terms of Langmuir-Hinshelwood kinetic model.

Keywords: Photocatalysis, Photodegradation, UV light, Dyes, Zinc oxide, Azo dyes

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 435-443

 

A new calcium(II) coordination polymer based on
a µ2-bridging tridentate 4-nitrobenzoate

Bikshandarkoil R Srinivasana, *, Santosh Y Shetgaonkara, Manav Saxenab & Christian Nätherc

aDepartment of Chemistry, Goa University, Goa 403 206, India
Email: srini@unigoa.ac.in

bDepartment of Chemistry, Indian Institute of Technology, Kanpur, 208 016 India

cInstitut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth Strasse 2, D-24118 Kiel, Germany

Received 17 September 2011; revised and accepted 16 January 2012

 

Reaction of a heptacoordinated Ca(II) compound [Ca(H2O)4(4-nba)2] (4-nba = 4-nitrobenzoate) with 3,5-dimethyl-pyrazole (dmp) leads to the formation of an eight coordinated Ca(II) compound, [[Ca(H2O)2(4-nba)2]·2dmp]n, containing two coordinated water molecules, two unique 4-nba ligands and two free dmp molecules in the lattice. The μ2-bridging tridentate binding mode of the unique 4-nba ligands results in the formation of a one-dimensional (1-D) coordination polymer. The title compound exhibits enhanced fluorescence emission. An analysis of the six different bridging binding modes of the 4-nba ligand in twenty two different structurally characterized 4-nitrobenzoate compounds is described.

Keywords: Coordination chemistry, Calcium, 4-Nitrobenzoates, 3,5-Dimethylpyrazole, Coordination polymers,
Metal organic
frameworks

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 444-452

 

Coordination chemistry of the multi-funtionalized
3-(diphenylphosphino)-1-propylamine ligand with ruthenium(II)

Geetika Borah* & Devajani Boruah

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

Email: geetikachem@yahoo.co.in

Received 27 June 2011; revised and accepted 27 January 2012

 

The reaction of RuCl2(PPh3)3 with two molar equivalents of a multi-functionalized ligand, 3-diphenylphosphino-1-propylamine (DPPA) yields two mononuclear, low spin, diamagnetic, octahedral neutral complexes, [RuCl22-P,N-DPPA)2] (1) and [RuCl22-P,N-DPPA)(PPh3)2] (2). The complexes have been characterized by conductivity measurements, FTIR, UV-vis, 1H and variable temperature 31P{1H} NMR, ESI(+)MS, TGA-DTG and cyclic voltammetry. The ESI(+) mass spectrogram of (1) shows molecular ion peak at m/z 658[M]+, indicating mononuclear nature of the complex . No fluxional behavior is observed from the variable temperature (200-300 K) 31P{1H} NMR spectra. The complexes (1) and (2) upon treatment with CH3CN in 1:1 molar ratio in the presence of NH4PF6 in dichloromethane solution afford the six-coordinate cationic complexes [RuCl(η2-P,N-DPPA)2(CH3CN)](PF6) (3) and [RuCl(η2-P,N-DPPA)(CH3CN)(PPh3)2](PF6) (4), respectively. The complexes (3) and (4) have also been characterized by FTIR, ESI(+)MS, 1H and 31P{1H} NMR spectra at room temperature. The complexes (1) and (2) are found to have high catalytic activity towards the oxidation of aromatic alcohols with H2O2/NaOCl as oxidant. Maximum conversion of 95% can be achieved under mild reaction conditions.

Keywords: Coordination chemistry, Multi-functional ligands, Ruthenium, Aminophophines

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 453-457

 

Copper(II) complexes with ONS donor ligand and triphenylphosphine:
Synthesis, characterization and catalytic applications

S Priyaregaa, M Muthu Tamizhb, S Ganesh Babub, R Karvembub & K Natarajana, *

aDepartment of Chemistry, Bharathiar University, Coimbatore 641 046, India

Email: k_natraj6@yahoo.com

bDepartment of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, India

Received 23 May 2011; revised and accepted 10 January 2012

A series of Cu(II) complexes of Schiff bases derived from the condensation of o-aminothiophenol with 2-hydroxy-
1-naphthaldehyde or salicylaldehyde or its derivatives (Br, Cl, NO2 or CH3) have been reported. The structural features of the complexes have been obtained from their elemental analyses, magnetic susceptibility, IR, electronic and EPR spectral studies. IR spectra suggest that these ligands act as tridentate dibasic donor coordinating through the phenolic oxygen, azomethine nitrogen and thiophenol sulphur atoms. Magnetic moments, electronic spectra and EPR spectra of the complexes suggested a square planar geometry around the Cu(II) ion. The redox behaviour of copper complexes has been studied by cyclic voltammetry. The new Cu(II) complexes have been utilized as catalysts for N-arylation of imidazole.

Keywords: Coordination chemistry, Copper, Schiff bases, Triphenylphosphine, N-Arylation, Imidazoles, ONS ligands

 

 

Indian Journal of Chemistry

Vol. 51A, March 2012, pp. 458-463

 

Synergetic influence of mercaptoacetic acid on the reaction of thiourea with methylene blue in acidic medium

 

K K Mishra* & Upasana Dwivedi

Department of Chemistry, Rani Durgavati University, Jabalpur 482 001, India

Email: kkmishra.chem@gmail.com

Received 2 April 2011; re-revised and accepted 18 January 2012

Thiourea and methylene blue interact in a mole ratio of 2:1 in the presence of HCl forming the corresponding disulphide and leucomethylene blue. The order in thiourea is unity while that in methylene blue is zero at higher concentrations (ca. >2.5×10-5 M). At lower concentrations, the order in methylene blue is -1/2; this kinetic deviation depends on the nature of the thiol acid exhibiting synergetic effect. Mercaptoacetic acid does not react with methylene blue under the prevailing conditions; however it exerts a synergetic effect on the reaction. The rate increases linearly on increasing [H+] with the reaction having a large negative entropy of activation. Electrospray induced mass spectrometry, 1H NMR and FTIR data indicate the participation of a persulphide-like species formed due to thiourea–mercaptoacetic acid interaction, which is perhaps responsible for the synergetic effect of mercaptoacetic acid.

Keywords:   Kinetics, Reaction mechanism, Synergetic effect, Mercaptoacetic acid,
Thiourea-methylene blue reaction