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 54A

NUMBER 7

JULY 2015

 

CONTENTS

 

 

843

 

Effective synthesis of quinoxalines over ceria based solid acids coated on honeycomb monoliths

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Venkatesh, S Z Mohamed Shamshuddin* &
N M Mubarak

 

 

 

Ceria-zirconia mixed oxide coated on honeycomb monolith is a facile catalyst for synthesis of quinoxalines with up to
89% yield and 100% selectivity. The ceria-zirconia catalyst coated on honeycomb is more effective than its powder form.

 

 

 

 

851

 

A comparative study of the morphologies and photocatalytic performances of bis[5-(2-pyridyl-tetrazolato)]diaquazinc(II) framework synthesized by hydrothermal and microwave methods

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Arti Chouhan, Peter Mayer & Ashutosh Pandey*

 

 

 

Bis[5-(2-pyridyltetrazolato)]diaquazinc(II) [(2-PTZ)2Zn(H2O)2] has been synthesized in situ by the reaction of 2-cyanopyridine, Zn(NO3)2.4H2O and NaN3 via both microwave assisted and conventional hydrothermal processes. The microwave process yields needle-like morphology, while the conventional process yields rhombohedral morphology. The photocatalyst with needle-like morphology exhibits 99% degradation of methylene blue in 100 min.

 

 

 

 

858

 

Instability of CL-20 exposed to the effects of α-particle

 

 

 

 

 

 

 

 

 

 

 

Lemi Türker

 

 

 

CL-20 is unstable in the presence of an α-particle which transfers its charge causing the cage structure of CL-20 to be destroyed. Removal of a single NO2 group from the 5- or 6-membered ring of CL-20 causes cage destruction in the dication form.

 

 

 

Notes

 

867

 

Reversible hydration of tetraaquabis(4-amino-benzoato)cobalt(II)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Kiran T Dhavskar & Bikshandarkoil R Srinivasan*

 

 

 

The octahedral red complex tetraaquabis(4-amino-benzoato)cobalt(II) undergoes a water induced crystalline–amorphous-crystalline transformation accompanied by chromotropism. On heating, the six coordinated octahedral complex is fully dehydrated to the four coordinated tetrahedral amorphous blue bis(4-amino-benzoato)cobalt(II), which on equilibration over water vapour can be rehydrated to the starting material, regaining its original properties.

 

pic

 

 

 

 

872

 

Al-doped zinc oxide nanostructures as transparent conductive window layer for photovoltaic applications

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R M Mohite* & R R Kothawale

 

 

 

AZO thin films prepared by chemical bath deposition method using zinc nitrate aqueous solution show high transmittance (>80%) and resistivity of ~1.4×10-3 Ω cm. The optical band gap of AZO material is  3.6 eV. Aluminium doping, particularly, 5 wt% Al doped ZnO, enhances the electron concentration and makes the film conductive.

 

 

 

 

877

 

DFT investigation of Diels-Alder reaction of
1,3-cyclohexadiene with tetracyclo[6.2.2.13,6.02,7]trideca-4,9,11-triene-9, 10-dicarboxylic anhydride dienophile

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rza Abbasoglu* & Abdurrahman Atalay

 

 

 

The mechanism and stereochemistry of the Diels-Alder reaction of 1,3-cyclohexadiene with tetracyclo[6.2.2.13,6.02,7]trideca-4,9,11-triene-9,10-dicarboxylic anhydride are investigated quantum chemically. Results show the anhydride double bond of the molecule to be anti-pyramidalized. Transition states [TS(syn,endo) and TS(syn,exo)] of syn cycloaddition reactions are more stable than transition states [TS(anti,endo) and TS(anti,exo)] of anti cycloaddition reactions, with little difference between stability of TS(anti,endo) and TS(anti,exo).

 

 

 

 

 

Authors for correspondence are indicated by (*)

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


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Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 843-850

 

 

Effective synthesis of quinoxalines over ceria based solid acids
coated on honeycomb monoliths

Venkatesha, b, S Z Mohamed Shamshuddina, b, * & N M Mubarakc

aChemistry Research Laboratory, HMS Institute of Technology, NH4, Kyathsandra, Tumkur, Karnataka, India

bResearch and Development Center, Bharathiar University, Coimbatore, India

cDepartment of Chemical Engineering, University of Malaya, Kuala Lumpur, Malaysia

Email: mohamed.shamshuddin@gmail.com

Received 31 January 2015; revised and accepted 22 June 2015

Solid acids of ceria such as sulfated ceria, ceria-zirconia mixed oxide and sulfated ceria-zirconia have been coated on honeycomb monoliths by slurry coating method. The catalyst materials are characterized by NH3-TPD for surface acidity, powder XRD for crystallinity and SEM for morphology. These materials are used as solid acid catalysts in the condensation reaction of various diamines and diketones to synthesize quinoxalines. In order to optimize the reaction conditions, the effect of reaction parameters such as the catalyst type, nature of the solvent, reaction temperature, nature of the catalyst and number of reaction cycles on the yield of the quinoxaline product has been studied. A correlation between the surface acidity and the catalytic activity is observed. The catalyst materials have also been prepared in their powder forms by impregnation method and their catalytic activity is compared with that of their honeycomb coated forms. The ceria based solid acids coated on honeycomb monoliths are economical, efficient and eco-friendly in quinoxaline synthesis.

Keywords: Catalysts, Solid acids, Quinoxalines, Honeycomb monoliths, Ceria, Sulfated ceria,
Ceria-zirconia, Zirconia

 

Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 851-857

 

 

A comparative study of the morphologies and photocatalytic performances of bis[5-(2-pyridyltetrazolato)]diaquazinc(II) framework synthesized by hydrothermal and microwave methods

Arti Chouhana, Peter Mayerb & Ashutosh Pandeya,*

aDepartment of Chemistry, MNNIT Allahabad, Allahabad 211004, India

bDepartment of Chemistry and Biochemistry, University of Munich, Butenandtstr. 5–13, 81377 Munich, Germany

Email: apandey@mnnit.ac.in

Received 15 February 2015; revised and accepted 12 June 2015

The metal organic framework compound, bis[5-(2-pyridyltetrazolato)]diaquazinc(II) [(2-PTZ)2Zn(H2O)2], has been synthesized by the reaction of 2-cyanopyridine, Zn(NO3)2.4H2O and NaN3 via both microwave assisted and conventional hydrothermal processes. The product obtained by the microwave process shows needle-like morphology, while that obtained by the conventional process shows rhombohedral morphology. The MOFs are characterised by scanning electronic microscopy, BET surface area analysis, room temperature photoluminescence and UV–vis spectroscopy. IR spectroscopy and single-crystal X-ray crystallographic studies of the MOF obtained by the microwave process have also been carried out. The average crystallite sizes of the two products, as determined by powder X-ray diffraction are found to be 72 nm and 26 nm respectively. Band gaps of the MOFs calculated by using the Tauc plots are 2.8 and 3.1 eV respectively. Their photocatalytic behavior using methylene blue under UV-vis irradiation has been investigated.

Keywords: Metal-organic framework, Microwave synthesis, Hydrothermal synthesis, Photocatalysis, Zinc

Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 858-866

 

 

Instability of CL-20 exposed to the effects of α-particle

Lemi Türker

Middle East Technical University, Department of Chemistry, Ankara-Turkey, 06531

Email: lturker@metu.edu.tr

Received 26 January 2015; revised and accepted 30 June 2015

Within the constraints of density functional theory, (B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p)), it is shown that 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtizane (CL-20) is unstable in the presence of an α-particle which transfers its charge causing the cage structure of CL-20 to be destroyed. Structural factors responsible for such a destruction are investigated. It has been found that removal of a single NO2 group from the 5- or 6-membered ring of CL-20 causes cage destruction in the dication form. Although, the carbon analog of CL-20 cage is stable in double cation form (only some distortions occur), even presence of a single nitro group on its 5- or 6- membered ring causes destruction of the carbon cage in dication form. Mono and bicentric nitrogen perturbations on the carbon cage of CL-20 (excluding the bicentric perturbation case in which nitrogens are on different pentagonal rings but located symmetrically) result in destruction on double cationic charging. Dication form of CL-20 cage (retaining cage nitrogens without nitro groups) is also unstable in double cation form.

Keywords: Theoretical chemistry, Density functional calculations, Decomposition, Stability, Cage destruction, Explosives, CL-20, HNIW

 

Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 867-871

 

 

Reversible hydration of tetraaquabis(4-aminobenzoato)cobalt(II)

Kiran T Dhavskar & Bikshandarkoil R  Srinivasan*

Department of Chemistry, Goa University, Goa 403206, India
Email: srini@unigoa.ac.in

Received 22 May 2015; accepted 30 June 2015

The octahedral red complex tetraaquabis(4-amino-benzoato)cobalt(II) (1) exhibits a water induced crystalline-amorphous-crystalline transformation accompanied by chromotropism. The loss of coordinated water from
[Co(4-aba)2(H2O)4]  (1)  (4-aba=4-aminobenzoate) on heating, leads to the formation of tetrahedral anhydrous
[Co(4-aba)2] (2). The amorphous blue compound (2) can be rehydrated to original composition by equilibrating (2) over water vapour. The rehydrated crystalline compound exhibits properties identical with (1). The variation in the structure and properties of (1) due to the coordination and decoordination of water are studied by spectral, thermal, magnetic and conductivity measurements.

Keywords: Chromotropism, Crystal-to-amorphous transformations, Dehydration, Rehydration, Reversible hydration, Cobalt, 4-Aminobenzoate

 

 

 

 

 

 

 

 

 

 

Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 872-876

 

 

Al-doped zinc oxide nanostructures as transparent conductive window layer
for photovoltaic applications

R M Mohitea, * & R R Kothawaleb

aSolapur University, Solapur 413 255, Maharashtra, India
Email: rmm1987@yahoo.com

bDepartment of Physics, Shri Shivaji Mahavidyalaya, Barshi, Solapur 413 411,
Maharashtra, India

Received 2 January 2015; revised and accepted 29 June 2015

Al-doped zinc oxide thin films have been prepared by chemical bath deposition using aqueous zinc nitrate solution and characterized by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and d.c. resistivity measurements. I-V measurements have been made in dark and under UV-light illumination. High conductivity and transparency of these thin films make them suitable for transparent conductive oxide and window layer applications in solar cells. This material also has potential use in optoelectronic devices such as photo-detectors, photonic crystals, ultraviolet light sensors and light emitting diodes.

Keywords: Nanostructures, Semiconductors, Oxides, Transparent conductive oxides, Thin films,
Optoelectronic devices, Zinc oxide, Aluminium

 

Indian Journal of Chemistry

Vol. 54A, July 2015, pp. 877-882

 

 

DFT investigation of Diels-Alder reaction of 1,3-cyclohexadiene with tetracyclo[6.2.2.13,6.02,7]trideca-4,9,11-triene-9, 10-dicarboxylic
anhydride dienophile

Rza Abbasoglu* & Abdurrahman Atalay

Department of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey

Email: rabbas@ktu.edu.tr

Received 28 January 2015; revised and accepted 29 June 2015

The geometry and the electronic structure of the tetracyclo-[6. 2.2.13,6.02,7]trideca-4,9,11-triene-
9,10-dicarboxylic anhydride (TTDA) have been investigated by DFT/B3LYP and /B3PW91 methods using the
6-311G(d,p) and 6-31+G(d,p) basis sets. Anhydride double bond of TTDA molecule is anti-pyramidalized. Potential energy surface of addition reaction of 1,3-cyclohexdiene to TTDA molecule (syn,endo-, syn,exo-, anti,endo- and anti,exo-addition) is calculated by B3LYP/6-31+G(d,p) method and configurations (transition states and products) corresponding to stationary points (saddle points and minima) is
determined. Kinetic and thermodynamic parameters of cycloaddition reactions have also been calculated. Syn addition reactions have lower activation energies, enthalpies, entropies and free energies than anti addition reactions. According to the results of theoretical calculations, syn addition reactions are expected to occur. The most stable reaction product is of the syn,endo-addition reaction. There is a correlation between the syn-π-face selectivity of the cycloaddition reaction and the pyramidalization of anhydride double bond of the TTDA molecule.

Keywords: Theoretical chemistry, Density functional calculations, Diels-Alder reaction, Syn-π-face selectivity, Pyramidalization, Steric hindrance