Indian Journal of Chemistry

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

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VOLUME 48A

NUMBER 4

April 2009

CONTENTS

 

473

Synthesis, crystal structures and protease activity of amino acid Schiff base iron(III) complexes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mohammed S Ameerunisha Begum, Sounik Saha, Munirathinam Nethaji & Akhil R Chakravarty*

 

 

 

 

Iron(III) complexes of amino acid Schiff base ligands, viz.,
N-salicylidene-L-methionine and N-salicylidene-L-phenylalanine have been prepared. Protein binding and photo-induced protein cleavage activity of these complexes are investigated using bovine serum albumin. The water soluble complexes show good BSA binding propensity and non-specific oxidative BSA cleavage activity in UV-A light of 365 nm.

 

 

 

480

Photocatalytic behavior of CeO2-TiO2 system for the degradation of methylene blue

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

G Magesh, B Viswanathan*, R P Viswanath,
T K Varadarajan

 

 

 

 

Mixed oxide CeO2-TiO2 has been employed in the coupled semiconductor configuration for photocatalytic decomposition of methylene blue.  This coupling has enabled the decomposition with visible light while with pure TiO2 only UV radiation can effect this decomposition.  Synergy between the two oxides and the importance of adsorption in photocatalytic decomposition of MB are demonstrated.

 

 

 

489

 

Characterization of CrOx-Y2O3 catalysts for fluorination of 2-chloro-1,1,1-trifluoroethane

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jun He, Ji-Qing Lu, Guan-Qun Xie, Lin Qian,
Ke-Feng Chen, Xue-Liang Zhang & Meng-Fei Luo*

 

 

 

 

Fluorination of 2-chloro-1,1,1-trifluoroethane has been carried out on CrOx-Y2O3 catalysts to synthesize 1,1,1,2-tetrafluoroethane.
Cr loading affects the catalyst structure and the catalytic activity. The CrFx, CrOxFy or Cr(OH)xFy phases originate from Cr(VI) species and are the active sites for the reaction.

 

 

 

 

498

 

Preparation of mesoporous silica with amphiphilic poly(oxyethylene)/poly(oxybutylene) diblock and poly(oxyethylene)/poly(oxypropylene) triblock copolymers as templates

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pius K Kipkemboi*, Paul C Kiprono &
Paul K Ndalut

 

 

 

 

Mesoporous silica can be formed with amphiphilic molecules acting as structure-directing templates in dilute systems. Micellar solutions of copolymers have been utilized for templated-silica synthesis under acidic conditions. Calcination of the silica products gives mesoporous materials. The effect of different block lengths of Pluronic surfactants, (EO)x-(PO)y-(EO)x, has been investigated and compared with that of poly(oxyethylene)/ poly(oxybutylene) diblock copoloymer. The EO-block length of the polymers determines the mesostructure of the silica.

 

 

 

504

 

Single ion transfer entropies in binary mixtures
of isodielectric protic ethylene glycol and
dipolar aprotic N,N-dimethylformamide vis-à-vis
3D-structuredness of aqueous co-solvents

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B K Dolui, S K Bhattacharya* & K K Kundu*

 

 

 

 

Transfer entropies, ∆S0t(i) of K+, Cl-, Pic- and Ph4As+/Ph4B- ions from protic ethylene glycol to its isodielectric mixtures of protophilic dipolar aprotic N,N-dimethylformamide have been determined by using TATB reference electrolyte assumption and measuring the solubilities of Ph4AsPic, KBPh4, KPic and KCl at different temperatures. ∆S0t(K+) and ∆S0t(Cl-) and their chemical effects in this completely non-aqueous media exhibit mirror-image behavior which is strikingly different from those in aquo-organic solvents studied earlier. This also reiterates that ∆S0t(i)
of small cations and anions can serve as a probe for the
3D-structuredness of aqueous co-solvents.

 

 

 

512

 

Structure and hydrogen bonding in binary mixtures of N,N-dimethylformamide with some dipolar aprotic and protic solvents by dielectric characterization

 

 

 

 

 

 

R J Sengwa*, Vinita Khatri & Sonu Sankhla

 

 

 

 

The low frequency limit static dielectric constant, optical frequency dielectric constant, excess dielectric constant, and the Kirkwood correlation factor of the binary mixtures of
N,N-dimethylformamide with water, ethyl alcohol, ethylene glycol, glycerol, dimethyl sulphoxide, acetone and 1,4-dioxane are investigated at 30°C over the entire composition range.

 

 

Notes

 

 

520

 

Prediction of pKa from basic principles: Ab initio and DFT studies on some molecules

 

 

 

 

 

 

 

 

 

P Hazarika, Rajib L Sarma, M Karim,
B Bezbaruah, R Kalita & C Medhi*

 

 

 

 

The quantum mechanical methodology based on the description of acid-base equilibrium for predicting pKa of some selected molecules with the continuum model of solvent polarization is reported. The method is useful for predicting pKa of selective molecules where the ionization of proton is basically controlled by the lone pair electrons of atomic site. However, it fails to predict pKa of strong and very weak acids.

 

 

526

 

Thermodynamic and transport properties of binary liquid mixtures of sulfolane with some lactones
at 308.15 K

 

 

 

 

 

 

 

 

Murali Krishna Patwari, Ranjith Kumar Bachu, Sathyanarayana Boodida, &
Satyanarayana Nallani*

 

 

 

 

The values of density, viscosity and speed of sound have been measured for binary liquid mixtures of γ-butyrolactone,
δ-valerolactone and ε-caprolactone with sulfolane over the entire composition range at T =308.15 K and atmospheric pressure. From this data, excess molar volume, deviation in viscosity and deviation in isentropic compressibility have been calculated. The results are fitted to a Redlich-Kister type polynomial equation to derive binary coefficients and standard deviations.

 

 

531

 

Synthesis and chelation ion exchange properties of
2, 4-dihydroxyacetophenone–biuret–formaldehyde terpolymer resin

 

 

 

 

 

 

 

S S Rahangdale , W B Gurnule* & A B Zade

 

 

 

 

The terpolymer resin 2, 4-dihydroxyacetophenone-biuret-formaldehyde has been synthesized by the condensation of
2, 4-dihydroxyacetophenone and biuret with formaldehyde in 2:1:3 molar ratios in presence of 2M hydrochloric acid as catalyst. Chelating ion exchange properties have been studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. The polymer shows higher selectivity for Fe3+ and Cu2+ ions than for Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. Study of distribution ratio as a function of pH indicates that the amount of metal ion uptake by resin increases with the increasing pH of the medium.

 

 

 

Authors for correspondence are indicated by (*)

 

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 473-479

 

 

Synthesis, crystal structures and protease activity of amino acid Schiff base iron(III) complexes

Mohammed S Ameerunisha Begum, Sounik Saha, Munirathinam Nethaji & Akhil R Chakravarty*

Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India

Email: arc@ipc.iisc.ernet.in

Received 23 January 2009; accepted 9 March 2009

Iron(III) complexes, (NHEt3)[Fe(III)(sal-met)2] and (NHEt3)[Fe(III)(sal-phe)2], of amino acid Schiff base ligands, viz., N-salicylidene-L-methionine and N-salicylidene-L-phenylalanine, have been prepared and their binding to bovine serum albumin (BSA) and photo-induced BSA cleavage activity have been investigated. The complexes are structurally characterized by single crystal X-ray crystallography. The crystal structures of the discrete mononuclear monoanionic complexes show FeN2O4 octahedral coordination geometry in which the tridentate dianionic amino acid Schiff base ligand binds through phenolate and carboxylate oxygen and imine nitrogen atoms. The imine nitrogen atoms are trans to each other. The Fe-O and Fe-N bond distances range between 1.9 and 2.1 Å. The sal-met complex has two pendant thiomethyl groups. The high-spin iron(III) complexes (meff ~ 5.9 mB) exhibit quasi-reversible Fe(III)/Fe(II) redox process near -0.6 V vs. SCE in water. These complexes display a visible electronic band near 480 nm in tris-HCl buffer assignable to the phenolate-to-iron(III) charge transfer transition. The water soluble complexes bind to BSA giving binding constant values of ~105 M-1. The complexes show non-specific oxidative cleavage of BSA protein on photo-irradiation with UV-A light of 365 nm.

Keywords: Bioinorganic chemistry, Protein binding, Protein cleavage, Crystal structure Amino acids, Iron

IPC Code: Int. Cl. 8 C07F15/04

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 480-488

 

 

Photocatalytic behavior of CeO2-TiO2 system for the degradation of methylene blue

 

G Magesh, B Viswanathan*, R P Viswanath, T K Varadarajan

National Centre for Catalysis Research, Department of Chemistry, Indian Institute of Technology Madras,
Chennai 600 036, India

Email: bvnathan@iitm.ac.in

Received 17 December 2008; revised and accepted 18 March 2009

Mixed oxide CeO2-TiO2 has been employed in the coupled semiconductor configuration for photocatalytic decomposition of methylene blue. This coupling has enabled decomposition with visible light while with pure TiO2 only UV radiation can effect this decomposition. Synergy between the two oxides and the importance of adsorption in photocatalytic decomposition of MB are demonstrated.

Keywords: Semiconductors, Coupled semiconductors, Photocatalysis, Visible light photocatalysis, Methylene blue, Ceria, Titania

IPC Code: Int Cl.8 B01J21/06; C01F17/00; C01G23/04

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 489-497

 

 

Characterization of CrOx-Y2O3 catalysts for fluorination of 2-chloro-1,1,1-trifluoroethane

Jun Hea, Ji-Qing Lua, Guan-Qun Xiea, Lin Qiana, Ke-Feng Chenb, Xue-Liang Zhangb & Meng-Fei Luoa, *

aZhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces,
Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China

Email: mengfeiluo@zjnu.cn

bZhejiang Qu Hua Fluor-Chemistry Company Limited, Quzhou 324004, China

Received 21 July 2008; revised and accepted 13 March 2009

The fluorination of 2-chloro-1,1,1-trifluoroethane (CF3CH2Cl) to synthesize 1,1,1,2-tetrafluoroethane (CF3CH2F) has been carried out on various CrOx-Y2O3 catalysts with different Cr loadings. The effect of Cr loading on the catalyst composition and structure has been investigated. X-ray diffraction and Raman results indicate that the CrOx species with high oxidation state (Cr(VI)) are well dispersed on the catalyst surface when the Cr loading was lower than 19.5 %. With increase in Cr loading, crystalline Cr2O3 and polymeric chromate are formed, which inhibit pre-fluorination of the catalysts. The catalysts are stable under the reaction conditions and the catalytic activity is strongly dependant on the pre-fluorinated CrOx content. The highest activity is obtained on a pre-fluorinated catalyst with a Cr loading of 19.5, with a 19 % CF3CH2Cl conversion at 320 oC, corresponding to a formation rate of 2.03 mmol h-1 g-1cat, which is 3-fold higher than the best result obtained over a Cr/MgF2 catalyst (0.68 mmol h-1 g-1cat) under similar conditions. The Cr-Al2O3 catalyst has also been prepared and tested for the probe reaction in this study. The activity is lower as compared to that of the Cr-Y2O3 catalyst with the same Cr content. The higher activity of Cr-Y2O3 catalyst may be due to the higher degree of dispersion of the Cr(VI) species on the Y2O3 support than on other supports. It is also found that the CrFx, CrOxFy or Cr(OH)xFy phases originating from higher oxidation state Cr(VI) species are the active sites for the fluorination reaction.

Keywords: Catalysts, Supported catalysts, Fluorination; Oxides, Chromium oxides; Yttrium oxide

IPC Code: Int. Cl.8  B01J23/26; B01J37/26; B01J39/10; C07C17/00

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 498-503

 

 

Preparation of mesoporous silica with amphiphilic poly(oxyethylene)/ poly (oxybutylene) diblock and poly(oxyethylene)/poly(oxypropylene) triblock copolymers as templates

Pius K Kipkemboi*, Paul C Kiprono & Paul K Ndalut

Department of Chemistry, Moi University, PO Box 1125, Eldoret, Kenya

Email: keronei@yahoo.com

Received 29 September 2008; revised and accepted 12 March 2009

Mesoporous silica can be formed with amphiphilic molecules acting as structure-directing templates in dilute systems. The effect of different block lengths of Pluronic surfactants, (EO)x-(PO)y-(EO)x, has been investigated and compared with that of poly(oxyethylene)/poly(oxybutylene) diblock copolymer in the formation of the mesoporous silica. Comparison is also made with earlier reports [Kipkemboi et al., Langmuir, 17 (2001) 5398] on the formation of the mesoporous materials. Micellar solutions of copolymers have been utilized for templated-silica synthesis under acidic conditions. Calcination of the silica products gives mesoporous materials. The EO-block length of the polymers determines the mesostructure of the silica. The synthesis temperature also influences particle size, wall thickness and pore diameter. The materials have been characterized by SAXS, transmission electron microscopy and nitrogen adsorption measurements.

Keywords:  Mesoporous compounds, Polymers, Copolymers, Block copolymers, Silica

IPC Code: Int. Cl.8 C08G18/00

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 504-511

 

 

Single ion transfer entropies in binary mixtures of isodielectric protic ethylene glycol and dipolar aprotic N, N-dimethylformamide vis-à-vis
3D-structuredness of aqueous co-solvents

B K Dolui, S K Bhattacharya* & K K Kundu*

Physical Chemistry Laboratories, Jadavpur University, Kolkata 700 032, India

Email: bijoy_dolui@yahoo.co.in/ skbhatt7@yahoo.co.in/ kkkundu@yahoo.com

Received 26 June 2008 ; revised and accepted 9 March 2009

Single ion transfer entropies, S0t(i) of some electrolytes like tetraphenylarsonium picrate, potassium tetraphenylborate, potassium picrate and potassium chloride from protic ethylene glycol to its isodielectric mixtures with 20, 40 and 60 wt % protophilic dipolar aprotic N,N-dimethylformamide have been determined at 25 °C using the Ph4AsPh4B TATB reference electrolyte assumption, and solubility of the salts measured at  15°, 20°, 30° and 35°C, and that at 25 °C reported earlier. S0t(i) of the ions as well as their chemical effects, ∆S0t, ch(i) (as obtained after correcting for the cavity effects, ∆S0t, cav(i) and ignoring Born-type electrostatic effect ∆S0t,Born(i), since the solvent mixtures are isodielectric), exhibit mirror-image behaviour of simple cation like K+ and anion like Cl-, which can be explained in the light of Kundu et al.’s four step transfer process. However, this feature in completely non-aqueous solvent system is strikingly different from that in aquo-cosolvent systems studied earlier, and offers an indirect evidence that the ‘characteristic mirror-image relationship’ of simple cations and anions, in aqueous cosolvent systems, is, as contended earlier, associated with 3D-‘structuredness’ of aqueous cosolvent systems. This reiterates that T∆S0t, ch(i) serves as a useful probe for the 3D-structuredness of aqueous cosolvents.

Keywords: Thermodynamics, Single ion transfer entropies, Transfer entropies, Isodielectric solvents, 3D- Structuredness

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 512-519

 

 

Structure and hydrogen bonding in binary mixtures of N,N-dimethylformamide with some dipolar aprotic and protic solvents by dielectric characterization

R J Sengwa*, Vinita Khatri & Sonu Sankhla

Dielectric Research Laboratory, Department of Physics, JNV University, Jodhpur 342 005, India

Email: rjsengwa@rediffmail.com

Received 28 July 2008; revised and accepted 24 February 2009

The low frequency limit static dielectric constant, optical frequency dielectric constant, excess dielectric constant, and the Kirkwood correlation factor of the binary mixtures of N,N-dimethylformamide with water, ethyl alcohol, ethylene glycol, glycerol, dimethyl sulphoxide, acetone and 1,4-dioxane over the entire composition range are investigated at 30oC. The values of these functions emphasize strong N,N-dimethylformamide-water hydrogen bond interaction due to breaking of water tetrahedral structure, whereas the N,N-dimethylformamide-alcohols complexations show a strong hydroxyl group number dependence with enhancement in the structural ordering of alcohols. The dielectric functions of N,N-dimethylformamide-water and N,N-dimethylformamide-1,4-dioxane mixtures reveal the similarity in the complexes, although the N,N-dimethylformamide-water interactions are stronger. The excess functions confirm the weak hydrogen bond interactions of N,N-dimethylformamide with dimethyl sulphoxide and acetone. The pronounced deviation in the excess functions of the studied mixtures confirms the formation of a stable adduct of stoichiometric ratio 1:1 in these systems.

Keywords: Hydrogen bonds, Solvent effects, Aprotic solvents, Protic solvents, Dielectric functions, Excess properties

IPC Code: Int. Cl.8 G01N31/00

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 520-525

 

 

Prediction of pKa from basic principles: Ab initio and DFT studies on some molecules

P Hazarika, Rajib L Sarma, M Karim, B Bezbaruah, R Kalita &C Medhi*

Chemistry Department, Gauhati University, PO Gauhati University, Guwahati 781 014, Assam, India

Email: chitrani@satyam.net.in

Received 22 July 2008; revised and accepted 16 March 2009

The quantum mechanical methodology based on the description of acid-base equilibrium for predicting pKa of some selected molecules with the continuum model of solvent polarization is shown. The method is useful for predicting pKa of selective molecules where the ionization of proton is basically controlled by the lone pair electrons of atomic site. However, it fails to predict pKa of strong and very weak acids. The differences in the experimental and theoretically obtained values are negligible. The applicability of this theory for estimating pKa values of molecules within the range of 4-5 is clearly demonstrated.

Keywords:Theoretical chemistry, Ab initio calculations, Acid base equilibrium, Acid dissociation, SCRF method, Continuum model

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 526-530

 

 

Thermodynamic and transport properties of binary liquid mixtures of sulfolane with some lactones at 308.15 K

Murali Krishna Patwari, Ranjith Kumar Bachu,  Sathyanarayana Boodida & Satyanarayana Nallani*

Department of Chemistry, Kakatiya University Warangal 506 009, India

Email: nallani_s@yahoo.com

Received 3 November 2008; revised and accepted 4 March 2009

The values of density, viscosity and speed of sound have been measured for binary liquid mixtures of γ-butyrolactone, δ-valerolactone and ε-caprolactone with sulfolane over the entire composition range at T =308.15 K and atmospheric pressure. From this data, excess molar volume, deviation in viscosity and deviation in isentropic compressibility have been calculated. The results are fitted to a Redlich-Kister type polynomial equation to derive binary coefficients and standard deviations. The results are interpreted in terms of molecular interactions between the unlike molecules.

Keywords: Thermodynamics, Transport properties, Viscosity, Excess properties, Lactones, Sulfolane

 

 

Indian Journal of Chemistry

Vol. 48A, April 2009, pp. 531-535

 

 

Synthesis and chelation ion exchange properties of 2, 4-dihydroxyacetophenone-biuret-formaldehyde terpolymer resin

S S Rahangdalea, W B Gurnuleb,* & A B Zadea

aDepartment of Chemistry, Laxminarayan Institute of Technology, RTM, Nagpur University, Nagpur 440 010, India

bDepartment of Chemistry, Kamla Nehru College, Nagpur 440 009, India

Email: wbgurnule@yahoo.co.in

Received 5 June 2008; revised and accepted 22 February 2009

The terpolymer resin 2, 4-dihydroxyacetophenone-biuret-formaldehyde has been synthesized by the condensation of  2, 4-dihydroxyacetophenone and biuret with formaldehyde in 2:1:3 molar ratios in presence of 2M hydrochloric acid as catalyst. UV-visible, IR and proton NMR spectral studies have been carried out to elucidate the structure of the resin. The terpolymer has proved to be a selective chelating ion exchange polymer for some metals. Chelating ion exchange properties of this polymer have been studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. Batch equilibrium method has been employed to study the selectivity of metal ion uptake and distribution coefficient over a wide pH range and in media of varying ionic strengths. The polymer shows higher selectivity for Fe3+ and Cu2+ ions than for Ni2+, Co2+, Zn2+, Cd2+ and Pb2+ ions. Study of distribution ratio as a function of pH indicates that the amount of metal ion uptake by resin increases with the increasing pH of the medium.

Keywords: Ion exchange, Terpolymers, Polymer resins, Resins, Distribution ratio

IPC Code: Int. Cl.8 B01J 39/00