@article { ISI:000268138200061, title = {Electronic structure and catalytic study of solid solution of GaN in ZnO}, journal = {Chemistry of Materials}, volume = {21}, number = {13}, year = {2009}, month = {JUL}, pages = {2973-2979}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Solid solutions of GaN in ZnO (Zn1-zGaz)(O1-xNx) (x and z \<= 0.15) have been prepared by simple solution combustion method, Except for minor changes in the lattice contraction, no significant change in the Wurtzite structure was observed. Raman and secondary ion mass spectrometry results show the direct Zn-N and Ga-N bonds in (Zn1-zGaz)(O1-xNx). Visible light absorption and XPS results demonstrate that N 2p states of nitride occupy the states above the O 2p valence band, and hence a change in optical band gap reduction occurs to similar to 2.5 eV from 3.37 eV for ZnO. Significant nitrogen fixation catalytic activity through NH3 formation has been observed at ambient pressure oil virgin (Zn1-zGaz)(O1-xNx) material, indicating its potential as a catalyst.

}, issn = {0897-4756}, doi = {10.1021/cm900682q}, author = {Mapa, Maitri and Thushara, K. S. and Saha, Biswajit and Chakraborty, Purushottam and Janet, C. M. and Viswanath, R. P. and Nair, C. Madhavan and Murty, K. V. G. K. and Gopinath, Chinnakonda S.} } @article { ISI:000266093800005, title = {MgCl2 center dot 4(CH3)(2)CHOH: a new molecular adduct and super active polymerization catalyst support}, journal = {Journal of Physical Chemistry C}, volume = {113}, number = {20}, year = {2009}, month = {MAY}, pages = {8556-8559}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A new molecular adduct, MgCl(2 center dot)4(CH3)(2)CHOH, has been synthesized and characterized for structural aspects and demonstrated for super active ethylene polymerization activity with TiCl4 to ultrahigh molecular weight polyethylene in high yield.

}, issn = {1932-7447}, doi = {10.1021/jp9026546}, author = {Thushara, K. S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000284238000010, title = {Fabrication of homogeneous nanoparticle/nanoneedle BaTiO3 and Ba0.8Sr0.2TiO3 smooth thin films by simple dip coating}, journal = {International Journal of Nanotechnology}, volume = {7}, number = {9-12, SI}, year = {2010}, month = {DEC}, pages = {919-931}, publisher = {INDERSCIENCE ENTERPRISES LTD}, address = {WORLD TRADE CENTER BLDG, 29 ROUTE DE PRE-BOIS, CASE POSTALE 896, CH-1215 GENEVA, SWITZERLAND}, abstract = {

Ferroelectric BaTiO3 (BTO) and Ba0.8Sr0.2TiO3 (BSTO) thin film materials have been successfully prepared by sol-gel processing and simple dip coating on glass and silicon supports. Above thin films were characterised by x-ray diffraction (XRD), Raman spectroscopy, photoelectron spectroscopy, thermal analysis, atomic force microscopy (AFM) and spectroscopic ellipsometry. Phase identification of BaTiO3 and Ba0.8Sr0.2TiO3 was performed by XRD. XRD and Raman spectroscopy investigations demonstrate that thc Ba0.8Sr0.2TiO3 film exhibits tetragonal structure. AFM analysis demonstrates the elongated nanospherical particles on glass substrate and nanowires on silicon substrate, which represent a strong influence of the crystallinity of underlying substrate on the grain morphology in this technique. The thin films on both the substrates are uniformly coated without any pinhole to significant area (similar to 2.5 cm(2)), and this method might be extended to large area uniform coating. Spectroscopic ellipsometric measurements reveal the exact thickness, refractive index and extinction coefficient of the thin films.

}, keywords = {barium strontium titanate, barium titanate, dip coating, fabrication, ferroelectric material, large area coating, nanotechnology, thin film}, issn = {1475-7435}, author = {Saini, Mamta and Vivekanand, K. and Poddar, Pankaj and Murty, K. V. G. K. and Thushara, K. S. and Gopinath, Chinnakonda S.} } @article { ISI:000295843900024, title = {MgCl2 center dot 6PhCH(2)OH - a new molecular adduct as support material for ziegler-natta catalyst: synthesis, characterization and catalytic activity}, journal = {Dalton Transactions}, volume = {40}, number = {41}, year = {2011}, month = {SEP}, pages = {10936-10944}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Benzyl alcohol has been used to prepare a single phase MgCl2 center dot 6BzOH molecular adduct as a support for an ethylene polymerization catalyst (Ziegler catalyst). The structural, spectroscopic and morphological aspects of the MgCl2 center dot 6BzOH molecular adduct and the Ziegler catalyst have been thoroughly studied by various physicochemical characterization techniques. The presence of MgO6 octahedrons due to the interaction of Mg2+ with six -OH groups of the benzyl alcohol is confirmed from a Raman feature at 703 cm(-1), and structural studies. The supported catalyst activity has been evaluated for the ethylene polymerization reaction. The lower polymerization activity of the titanated Ziegler-Natta catalyst compared with a standard catalyst is attributed to the strong interaction of titanium chloride with the support and associated electronic factors.

}, issn = {1477-9226}, doi = {10.1039/c1dt10786k}, author = {Gnanakumar, Edwin S. and Thushara, K. S. and Bhange, Deu S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000286868600075, title = {Toward an understanding of the molecular level properties of ziegler-natta catalyst support with and without the internal electron donor}, journal = {Journal of Physical Chemistry C}, volume = {115}, number = {5}, year = {2011}, month = {FEB}, pages = {1952-1960}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Two Ziegler-Natta catalysts supported on molecular adducts, namely, MgCl2 center dot 6EtOH (ME) and MgCl2 center dot 5EtOH center dot EtOOCPh (Est-ME), have been prepared. A systematic effort has been made to unravel the molecular level structure property relationships of the catalysts and adducts. Ethylbenzoate is an internal electron donor, and its in situ formation through EtOH+PhCOCl coupling is successfully achieved. The above adduct has been treated with TiCl4, and the resultant catalyst (Ti/Est-ME) is evaluated for ethylene polymerization activity. Rand C-13 CP/MAS NMR of Est-ME (Ti/Est-ME) show carbonyl features at 1730 (1680) cm(-1) and 169 (170) delta, respectively, providing direct support for the presence of ester as an integral part. In spite of low surface area, Ti/Est-ME gives higher yield for ethylene polymerization than the one derived from ME. The results indicate that electronic environment is more important than surface area or any other single factor in determining the polymerization activity.

}, issn = {1932-7447}, doi = {10.1021/jp1078289}, author = {Thushara, K. S. and Gnanakumar, Edwin S. and Mathew, Renny and Jha, Ratnesh Kumar and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Sarma, Krishna and Padmanabhan, Sudhakar and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000308361400011, title = {MgCl2 center dot 4((CH3)(2)CHCH2OH): a new molecular adduct for the preparation of TiClx/MgCl2 catalyst for olefin polymerization}, journal = {Dalton Transactions}, volume = {41}, number = {37}, year = {2012}, month = {JUL}, pages = {11311-11318}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A new molecular adduct of MgCl2 with isobutanol, namely MgCl2 center dot 4((CH3)(2)CHCH2OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O-6 breathing mode and the formation of the adduct. The diffraction feature at 2 theta = 7.8 degrees (d = 11.223 angstrom) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl2 isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.

}, issn = {1477-9226}, doi = {10.1039/c2dt31211e}, author = {Thushara, K. S. and Gnanakumar, Edwin S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000311190800033, title = {MgCl2 center dot 6C(6)H(11)OH: a high mileage porous support for ziegler-natta catalyst}, journal = {Journal of Physical Chemistry C}, volume = {116}, number = {45}, year = {2012}, month = {NOV}, pages = {24115-24122}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A new and single phase molecular adduct of MgCl2 with six cyclohexanol molecules MgCl2 center dot 6C(6)H(11)OH (MgCyOH) has been synthesized. Structural insight to this adduct was obtained by a variety of physicochemical methods. C-13 CPMAS spectrum and single pulse MAS spectra with high power proton decoupling recorded at different relaxation time showed the presence of two different sets of magnetically unequal cylcohexanol molecules present around Mg2+. A Raman feature of MgCyOH at 712 cm(-1) confirms that cylcohexanol molecules are present around Mg2+ in an octahedral environment. MgCyOH has been used as support material to prepare Ziegler-Natta (Z-N) active catalyst. Textural property of above Z-N catalyst exhibits high surface area (236 m(2)/g) with high porosity. Above active catalyst has been screened for ethylene polymerization. Depending on the cocatalyst employed (Me3Al, Et3Al, and iso-Bu3Al) and ethylene pressure, polyethylene yield varies an order of magnitude, from 378 to 3570 g/g catalyst, indicating a possible creation of different active sites and different interaction between cocatalyst and catalyst.

}, issn = {1932-7447}, doi = {10.1021/jp3074078}, author = {Gnanakumar, Edwin S. and Thushara, K. S. and Gowda, Ravikumar R. and Raman, Sumesh K. and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Chakraborty, Debashis and Gopinath, Chinnakonda S.} } @article { ISI:000331861300008, title = {Solid-state NMR investigations of a MgCl2 center dot 4(CH3)(2)CHCH2OH molecular adduct: a peculiar case of reversible equilibrium between two phases}, journal = {Journal of Physical Chemistry A}, volume = {118}, number = {7}, year = {2014}, month = {FEB}, pages = {1213-1219}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

MgCl2 center dot xROH molecular adducts are extensively employed as a support material for Ziegler-Natta polyolefin catalysis. However, their structural properties are not well understood. Recently, we reported on the preparation of an isobutanol adduct, MgCl2 center dot 4(CH3)(2)CHCH2OH (MgiBuOH) (Dalton Trans. 2012, 41, 11311), which is very sensitive to the preparation conditions, such as the temperature and refluxing time. For the present study, the structural properties of MgiBuOH adducts prepared under different conditions have been investigated thoroughly by solid-state NMR and nonambient XRD. Formation of two phases has been confirmed, and in situ variable temperature solid-state NMR measurements confirm the coexistence of two phases as well as the oscillation from one to another phase. It is expected that such molecular adducts could have a significant role in organic transformation reactions due to an oscillating structural component. An understanding of phase oscillation with the Mg2+ ion as the central metal ion might shed some light toward understanding various biological and structural functions.

}, issn = {1089-5639}, doi = {10.1021/jp412331s}, author = {Thushara, K. S. and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Gopinath, Chinnakonda S.} } @article { ISI:000329266500032, title = {Structural investigations of porous MgCl2-2-butanol molecular adduct as support for olefin polymerization}, journal = {Applied Catalysis A-General}, volume = {469}, year = {2014}, month = {JAN}, pages = {267-274}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A new heterogeneous Ziegler-Natta (Z-N) catalyst support material, MgCl2 center dot 4(CH3CH(OH)CH2CH3) (Mg2BuOH) has been synthesized. 2-Butanol, a linear, secondary alcohol was chosen for the generation of an active MgCl2 support which results in a Z-N catalyst with TiCl4. Significant feature of this work is the formation of rod shaped molecular adduct with highly porous character. Adduct material is characterized by XRD, TG-DTA, Raman spectroscopy, solid-state NMR and SEM. Activity of the Z-N catalyst supported on Mg2BuOH for ethylene polymerization is comparable with that of commercially available heterogeneous Z-N catalyst. However, there is scope to improve the activity by optimizing textural properties. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {heterogeneous catalysis, MgCl2, Molecular adduct, NMR, Polyolefin, Ziegler-Natta catalyst}, issn = {0926-860X}, doi = {10.1016/j.apcata.2013.10.002}, author = {Thushara, K. S. and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Gopinath, Chinnakonda S.} }