Sunajadevi, K R; Sugunan, S(Elsevier, October , 2004)
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Abstract:
Chromia loaded sulfated titania has been synthesized via sol–gel route with different chromia loadings. These catalysts are characterized using conventional techniques such as XRD analysis, FTIR analysis, surface area and pore volume measurements, EDX, SEM and UV–Vis diffuse reflectance spectral analysis. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. Activity studies are done in the liquid phase. It has been concluded that Lewis acid sites are responsible for the benzylation of arenes with benzyl chloride.
Cimi, Daniel A; Dr.Sugunan, S(Cochin University of Science And Technology, January 23, 2014)
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Abstract:
The use of catalysts in chemical and refining processes has increased
rapidly since 1945, when oil began to replace coal as the most important
industrial raw material. Catalysis has a major impact on the quality of
human life as well as economic development. The demand for catalysts is
still increasing since catalysis is looked up as a solution to eliminate or
replace polluting processes. Metal oxides represent one of the most
important and widely employed classes of solid catalysts. Much effort has
been spent in the preparation, characterization and application of metal
oxides. Recently, great interest has been devoted to the cerium dioxide
(CeO2) containing materials due to their broad range of applications in
various fields, ranging from catalysis to ceramics, fuel cell technologies,
gas sensors, solid state electrolytes, ceramic biomaterials, etc., in addition
to the classical application of CeO2 as an additive in the so-called three way
catalysts (TWC) for automotive exhaust treatment. Moreover, it can
promote water gas shift and steam reforming reactions, favours catalytic
activity at the interfacial metal-support sites. The solid solutions of ceria
with Group IV transitional-metals deserve particular attention for their
applicability in various technologically important catalytic processes.
Mesoporous CeO2−ZrO2 solid solutions have been reported to be employed
in various reactions which include CO oxidation, soot oxidation, water-gas
shift reaction, and so on. Inspired by the unique and promising
characteristics of ceria based mixed oxides and solid solutions for various
applications, we have selected ceria-zirconia oxides for our studies. The
focus of the work is the synthesis and investigation of the structural and
catalytic properties of modified and pure ceria-zirconia mixed oxide.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
A series of rare-earth neodymia supported vanadium oxide catalysts with various V205 loadings ranging from 3 to 15 wt.% were prepared
by the wet impregnation method using ammonium metavanadate as the vanadium precursor. The nature of vanadia species formed on the
support surface is characterized hy a series of different physicochemical techniques like X-ray diffraction (XRD). Fourier transform infrared
spectroscopy (FTIR). BET surface area, diffuse reflectance UV-vis spectroscopy (DR UV-vis), thermal analysis (TG-DTG/DTA) and SEM.
The acidity of the prepared systems were verified by the stepwise temperature programmed desorprion of ammonia (NH3-TPD) and found that
the total acidity gets increased with the percentage of vanadia loading. XRD and FT1R results shows the presence of surface dispersed vanadyl
species at lower loadings and the formation of higher vanadate species as the percentage composition of vanadia is increased above 9 wt.%.
The low surface area of the support. calcination temperature and the percentage of vanadia loading are found to influence the formation of
higher vanadia species. The catalytic activity of the V205-Nd203 catalysts was probed in the liquid phase hydroxylation of phenol and the
result show that the present catalysts are active at lower vanadia concentrations.
Mohammed Yusuff, K K; Anas, K(Elsevier, Applied Catalysis A :General 264 (2004) 213–217, December 25, 2003)
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Abstract:
CoMo/gama-Al2O3 catalysts for hydrodesulphurisation activity were prepared by making use of the molecular designed dispersion (MDD)
method. Molybdenum and cobalt pyrrolidine-N-carbodithioate (Pydtc) complexes were used for the incorporation of metals on the support.
The catalysts were characterized by elemental analysis, low temperature oxygen chemisorption, temperature programmed reduction (TPR)
and laser Raman spectroscopy. The hydrodesulphurisation activity of all the catalysts were carried out and results were compared with those
of the catalysts prepared through the conventional method. Higher molybdenum dispersion, smaller molybdenum clusters, lower reduction
temperature of catalyst and better hydrodesulphurisation activity were observed for the catalysts prepared through the MDD method
The title reaction was undertaken to establish the interaction between amantadine and molybdate at physiological pH. Identical FTIR spectra, TG-DTA curves and CHN data of the complexes formed from three solutions at pH 1.5, 7.4 and 8.0 indicate that the same complex was formed at all the three pHs. The FTIR spectrum shows shift in peaks corresponding to primary amino group of the drug due to coordination to molybdate. An octahedral geometry is assigned to the complex. The kinetics of the complexation has been studied at low concentrations of the reactants using UV-visible spectrophotometry. At pH 7.4, the initial rate varies linearly with [molybdate]. A plot of initial rate versus [drug] is linear passing through origin. These results indicate that the drug and molybdate react at pH 7.4 even at low concentrations. At pH 1.5, the rate increases linearly with increase in [drug] but decreases with [molybdate]. The effect of pH and ionic strength on the rate of the reaction has also been studied. A suitable mechanism has been proposed for the reaction. Reaction between the drug and molybdate even at low concentrations and the fact that the amino group of amantadine required to be free for its function as antiviral, is bound to molybdate in the complex suggests that simultaneous administration of the drug and molybdate supplements should be avoided.
Biju, Francis; Dr. M. L. P. Reddy(Cochin University of Science and Technology, January 6, 2016)
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Abstract:
The fascinating photoluminescence properties of trivalent europium (Eu3+)
coordination compounds have aroused tremendous interest in recent years due
to their potential applications ranging from biomedical analysis to material
science. The Eu3+ ions have excellent luminescent features such as long-lived
excited-state lifetimes (μs–ms range) and narrow, easily recognizable line-like
red emission bands with large Stokes shifts. A big challenge in the chemistry of
lanthanide ions is to develop luminescent europium complexes that can be
sensitized by visible-light. This field has become much more important because
of the demand for less-harmful labelling reagents in the life sciences and lowvoltage-
driven pure-red emitters in optoelectronic. Thus, the primary objective
of the present research work is to design and develop novel visible-light
sensitized Eu3+-β-diketonate complexes with impressive photophysical
propertiesThe thesis comprises of four chapters which are presented as independent
units and therefore the structure formulae, schemes, figures and references are
numbered chapterwise. The introductory chapter highlights a background
sketch of the use of β-diketonates as antenna ligands for Eu3+ ion, the recent
developments in visible light excitable Eu3+-β-complexes and an overview of
the various methods of synthesis of Eu3+-based silica hybrid materials, their
photophysical properties and possible applications
Prathapachandra Kurup, M R; Suma, S; Sudarsana Kumar, M R; Siji, V L(Elsevier, February 26, 2010)
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Abstract:
Eight new transition metal complexes of benzaldehyde-N(4)–phenylsemicarbazone have been synthesized
and characterized by elemental analyses, molar conductance, electronic and infrared spectral
studies. In all the complexes, the semicarbazone is coordinated as neutral bidentate ligand. 1H NMR
spectrum of [Zn(HL)2(OAc)2] shows that there is no enolisation of the ligand in the complex. The magnetic
susceptibility measurements indicate that Cr(III), Mn(II), Fe(III), Co(II) and Cu(II) complexes are
paramagnetic and Ni(II) is diamagnetic. The EPR spectrum of [Mn(HL)2(OAc)2] in DMF solution at 77K
shows hyperfine sextet with low intensity forbidden lines lying between each of the two main hyperfine
lines. The g values calculated for the [Cu(HL)2SO4] complex in frozen DMF, indicate the presence of
unpaired electron in the dx2−y2 orbital. The metal ligand bonding parameters evaluated showed strong
in-plane bonding and in-plane bonding. The ligand and complexes were screened for their possible
antimicrobial activities.
Description:
Spectrochimica Acta Part A 76 (2010) 22–28 doi:10.1016/j.saa.2010.02.035
Pazhoor Bijumon, Varghese; Mohanan, P; Mailadil, Thomas Sebastian(The Japan Society of Applied Physics, 2002)
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Abstract:
Microwave ceramic dielectric materials Ca5Nb2TiO12 and Ca5Ta2TiO12 have been prepared by a conventional solid-state
ceramic process. The structure was studied by X-ray diffraction and the dielectric properties were characterized at microwave
frequencies. The ceramics posses a relatively high dielectric constant, very low dielectric loss (Q5 x f > 30000GHz) and
small temperature variation of resonant frequency. These materials are potential candidates for dielectric resonator
applications in microwave integrated circuits. [DOI: 10. 1 143/JJAP.41.3834]
Pramila Devi, D S; Dr.Sunil,Narayanankutty K(Cochin University of Science And Technology, December , 2012)
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Abstract:
The search for new materials especially those possessing special
properties continues at a great pace because of ever growing demands of the
modern life. The focus on the use of intrinsically conductive polymers in
organic electronic devices has led to the development of a totally new class of
smart materials. Polypyrrole (PPy) is one of the most stable known conducting
polymers and also one of the easiest to synthesize. In addition, its high
conductivity, good redox reversibility and excellent microwave absorbing
characteristics have led to the existence of wide and diversified applications for
PPy. However, as any conjugated conducting polymer, PPy lacks processability,
flexibility and strength which are essential for industrial requirements. Among
various approaches to making tractable materials based on PPy, incorporating
PPy within an electrically insulating polymer appears to be a promising method,
and this has triggered the development of blends or composites. Conductive
elastomeric composites of polypyrrole are important in that they are composite
materials suitable for devices where flexibility is an important parameter.
Moreover these composites can be moulded into complex shapes.
In this work an attempt has been made to prepare conducting elastomeric
composites by the incorporation of PPy and PPy coated short Nylon-6 fiber
with insulating elastomer matrices- natural rubber and acrylonitrile butadiene
rubber. It is well established that mechanical properties of rubber composites
can be greatly improved by adding short fibers. Generally short fiber
reinforced rubber composites are popular in industrial fields because of their
processing advantages, low cost, and their greatly improved technical
properties such as strength, stiffness, modulus and damping. In the present
work, PPy coated fiber is expected to improve the mechanical properties of the
elastomer-PPy composites, at the same time increasing the conductivity. In
addition to determination of DC conductivity and evaluation of mechanical
properties, the work aims to study the thermal stability, dielectric properties
and electromagnetic interference shielding effectiveness of the composites.
The thesis consists of ten chapters.
Description:
Department of Polymer Science and Rubber Technology,
Cochin University of Science and Technology
Pramila Devi, D.S.; Dr. Sunil K. Narayanan Kutty(Cochin University of Science and Technology, December 12, 2012)
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Abstract:
The search for new materials especially those possessing special
properties continues at a great pace because of ever growing demands of the
modern life. The focus on the use of intrinsically conductive polymers in
organic electronic devices has led to the development of a totally new class of
smart materials. Polypyrrole (PPy) is one of the most stable known conducting
polymers and also one of the easiest to synthesize. In addition, its high
conductivity, good redox reversibility and excellent microwave absorbing
characteristics have led to the existence of wide and diversified applications for
PPy. However, as any conjugated conducting polymer, PPy lacks processability,
flexibility and strength which are essential for industrial requirements. Among
various approaches to making tractable materials based on PPy, incorporating
PPy within an electrically insulating polymer appears to be a promising method,
and this has triggered the development of blends or composites. Conductive
elastomeric composites of polypyrrole are important in that they are composite
materials suitable for devices where flexibility is an important parameter.
Moreover these composites can be moulded into complex shapes.
Dielectric ceramics based on solid solution phases of [RE1_x= REr]TiNb06, where REI_s = Nd, Pr, Sm and RE' = Dy, Gd and Y, were prepared by the conventional solid-state ceramic route for values of x. The ceramic samples are characterized by X-ray diffraction and microwave methods. Ceramics based on RE (Pr, Nd and Sm) belonging to aeschynite group shows positive value of Tf and those based on RE (Gd, Dy and Y) belonging to euxenite group show negative value of r f. The solid solution phases between the aeschynite and the euxenite group shows intermediate dielectric constant and r f values. The results indicate the possibility of tailoring the dielectric properties by varying the composition of the solid solution phases. The range of solid solubility of euxenite in aeschenite and aeschenite
in euxenite are different for different rare earth ions
Mohammed Yusuff, K K; Manju, Sebastian; Arun, Vasudevan; Robinson, P P; Leeju, Pally; Digna, Varghese; Varsha, Gopalakrishnan(Taylor & Francis, Journal of Coordination Chemistry, October 15, 2009)
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Abstract:
The mononuclear cobalt(II) complex [CoL2] H2O (where HL is quinoxaline-2-carboxalidine-
2-amino-5-methylphenol) has been prepared and characterized by elemental analysis, conductivity
measurement, IR, UV-Vis spectroscopy, TG-DTA, and X-ray structure determination.
The crystallographic study shows that cobalt(II) is distorted octahedral with each tridentate
NNO Schiff base in a cis arrangement. The crystal exhibits a 2-D polymeric structure parallel to
[010] plane, formed by O-H...N and O-H... O intermolecular hydrogen bonds and pye
stacking interactions, as a racemic mixture of optical enantiomers. The ligand is a Schiff base
derived from quinoxaline-2-carboxaldehyde
Reena Mary, A P; Narayanan, T N; Vijutha, Sunny; Sakthi Kumar, D; Yasuhiko, Yoshida; Joy, P A; Anantharaman, M R(Springer, 2010)
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Abstract:
Bio-compatible magnetic fluids having high
saturation magnetization find immense applications in
various biomedical fields. Aqueous ferrofluids of superparamagnetic
iron oxide nanoparticles with narrow size
distribution, high shelf life and good stability is realized by
controlled chemical co-precipitation process. The crystal
structure is verified by X-ray diffraction technique. Particle
sizes are evaluated by employing Transmission electron
microscopy. Room temperature and low-temperature magnetic
measurements were carried out with Superconducting
Quantum Interference Device. The fluid exhibits good
magnetic response even at very high dilution (6.28 mg/cc).
This is an advantage for biomedical applications, since only
a small amount of iron is to be metabolised by body organs.
Magnetic field induced transmission measurements carried
out at photon energy of diode laser (670 nm) exhibited
excellent linear dichroism. Based on the structural and
magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of
radiofrequencies.