Sreekumar, K(Indian academy of science, February 24, 2003)
[+]
[-]
Abstract:
Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4×5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.
Knoevenagel condensation between carbonyl compounds and active methylene compounds as well as three component Mannich reaction between aldehydes, ketones and amines proceeded smoothly in water with good to excellent yield and high selectivity in the presence of zero and first generation poly(amidoamine) (PAMAM) dendrimers. The products and the catalyst were separated by simple biphasic extraction. The catalyst was found to be reusable.
Mohammed Yusuff, K K; Robinson, P P; Arun, Vasudevan; Manju, Sebastian; Ummer Aniz, Chennampilly(Springer, June 5, 2009)
[+]
[-]
Abstract:
The metal complex, [Ni(en)2(H2O)2](NO3)2
(en = ethylenediamine), was decomposed in a static furnace
at 200 C by autogenous decomposition to obtain
phase pure metallic nickel nanocrystallites. The nickel
metal thus obtained was studied by XRD, IR spectra, SEM
and CHN analysis. The nickel crystallites are in the
nanometer range as indicated by XRD studies. The IR
spectral studies and CHN analyses show that the surface is
covered with a nitrogen containing species. Thermogravimetric
mass gain shows that the product purity is high
(93%). The formed nickel is stable and resistant to oxidation
up to 350 C probably due to the coverage of nitrogen
containing species. Activation energy for the oxidation of
the prepared nickel nanocrystallites was determined by
non-isothermal methods and was found to depend on the
conversion ratio. The oxidation kinetics of the nickel
crystallites obeyed a Johnson–Mehl–Avrami mechanism
probably due to the special morphology and crystallite
strain present on the metal.
Sugunan, S; Renuka, N K(Indian Journal of Chemistry, June , 2002)
[+]
[-]
Abstract:
A series of supported vanadia systems have been prepared by
excess solvent technique using La203 and DY203 as supports.
Physical characterization has been carried out using XRD, FTIR,
TG studies, BET surface area measurement, pore volume analysis
etc. Cyclohexanol decomposition has been used as a test reaction
for evaluating the acid base properties of the supported system.
The oxidative dehydrogenation of ethylbenzene has been
employed as a chemical probe reaction to examine the catalytic
activity. The active species correspond to amorphous and
crystalline tetrahedral vanadyl units in the supported system.
Sankara Raman, S; Nampoori, V P N; Vallabhan, C P G; Ambadas, G; Sugunan, S(American Institute of Physics, 1995)
[+]
[-]
Abstract:
The thermal diffusivity of y-alumina is determined by the photoacoustic method. The method is
calibrated by determining the thermal diffusivity of copper and aluminum. The effect of the
chemisorbed hydroxyl groups or thermal diffusivity is studied by degassing the sample at different
temperatures.
The heterogeneous photocatalytic degradation of methylorange over TiO2 is studied
and is found to be cost effective. Effect of Zirconium metal incorporation over titania system is investigated. Photocatalytic degradation of methylorange using solar radiation is
found to be highly economical when compared with the processes using artificial UV
radiation, which require substantial electrical power input. The characterization of titania as
well as modified zirconium metal doped titania systems are done using XRD, FTIR and
EDAX measurements. The catalytic activities of different systems are also compared and is
tried to correlate with the crystallite size and presence of dopant metal.
Shali, N B; Sugunan, S(Springer Netherlands, 2007)
[+]
[-]
Abstract:
Lanthana modified sol-gel titania is prepared
through particulate sol-gel route and the physico-chemical
characterizations of the prepared systems were done using
X-Ray diffration, EDX, BET surface area-pore volume measurements
and TG-DTG analysis. Benzophenone was observed
to be the sole product in the TiO2 photocatalyzed
oxidation of benzhydrol in oxygen purged acetonitrile. The
influence of various parameters, like irradiation time, amount
of catalyst, concentration of the catalyst and other factors on
the photocatalytic oxidation has been investigated. The proposed
mechanism envisages the involvement of a superoxide
radical anion.
Poly(6-tert-butyl-3,4-dihydro-2H-1,3-benzoxazine) was synthesized by
thermally activated cationic ring opening polymerization. The structure of the
polymer was confirmed by spectral and thermal studies. The highest occupied
molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were
estimated using cyclic voltammetry and optical absorption. Modulated photocurrent
measurement technique was employed to study the spectral and field dependence of
photocurrent. Photocurrent of the order of 1.5 micro A/m2 was obtained for polymer at a
biasing electric field of 40 V/mico m.
Sugunan, S; Binitha, N N(Journal of Applied Polymer Science,Wiley InterScience, March 16, 2007)
[+]
[-]
Abstract:
In situ polymerization of aniline is done
inside the pillared clay matrix. The nonswellable pillared
clay confined matrix allows efficient polymerization that
leads to nanofibrous morphology. As a result high polymer
order and crystallinity is attained and is evident from
XRD patterns. The strong interaction between the clay
layers and polyaniline (PANI) is understood from FTIR and DRS spectra. Additionally these analytical results suggest that the prepared PANI is in the doped state. The
PANI/pillared clay nanocomposite formation gives additional
thermal stability to the polymer backbone and is clear from the DTG curves.
Girish Kumar,K; Saji John,Konnully; Remalakshmy,Poduval(Department of Applied Chemistry, April 2, 2005)
[+]
[-]
Abstract:
A set of six new polystyrene anchored metal
complexes have been synthesized by the reaction of the
metal salt with the polystyrene anchored Schiff base of
vanillin. These complexes were characterized by elemental
analyses, Fourier transform infrared spectroscopy, diffuse
reflectance studies, thermal studies, and magnetic susceptibility
measurements. The elemental analyses suggest a
metal : ligand ratio of 1 : 2. The ligand is unidentate and
coordinates through the azomethine nitrogen. The Mn(II),
Fe(III), Co(II), Ni(II), and Cu(II) complexes are all paramagnetic
while Zn(II) is diamagnetic. The Cu(II) complex is
assigned a square planar structure, while Zn(II) is assigned
a tetrahedral structure and Mn(II), Fe(III), Co(II), and Ni(II)
are all assigned octahedral geometry. The thermal analyses
were done on the ligand and its complexes to reveal their
stability. Further, the application of the Schiff base as a
chelating resin in ion removal studies was investigated. The
polystyrene anchored Schiff base gave 96% efficiency in the
removal of Ni(II) from a 20-ppm solution in 15 min, without
any interference from ions such as Mn(II), Co(II), Fe(III),
Cu(II), Zn(II), U(VI), Na , K , NH4
, Ca2 , Cl , Br , NO3
,
NO2
,and CH3CO2
. The major advantage is that the removal
is achieved without altering the pH.
Transition metal-loaded (3%) nanocrystalline sulfated titania (ST) powders are prepared using the sol–gel technique. Anatase is found as the active phase in all the samples. Sulfate ion impregnation decreases the crystallite size and stabilizes the anatase phase of TiO2. Acidity of the samples is found to increase by the incorporation of sulfate ion and also by the modification by transition metal ions. All the prepared catalysts are found stable up to 700 °C.
Prathapachandra Kurup, M R; Alex, Punnoose; Manoj, E(Elsevier, October 17, 2008)
[+]
[-]
Abstract:
Ten new copper(II) complexes of five potential bisthiocarbohydrazone and biscarbohydrazone ligands
were synthesized and physico-chemically characterized. The spectral and magnetic studies of compounds
are consistent with the formation of asymmetric di-, tri- or tetranuclear copper(II) complexes of deprotonated
forms of respective ligands. The variable temperature magnetic susceptibility measurements of all
complexes showantiferromagnetic interactions between the Cu(II) centers, in agreement with very broad
powder EPR spectra. However, frozen solution EPR spectral studies are found in contradiction with the
solid-state magnetic studies and indicate that the complexes are not very stable in solutions; the possible
fragmentations of complexes are found in agreement with MALDI MS results. The EPR spectral simulation
of most of the compounds is in agreement with the presence of two uncoupled Cu(II) species in solution.
Mohammed Yusuff, K K; Ahmed Yasir,Vakayil; Mohan Das,P N(Elsevier, International Journal of Inorganic Materials, August 12, 2001)
[+]
[-]
Abstract:
Highly crystalline, ultra fine TiO (anatase) having high surface area has been prepared by thermal hydrolysis of titanyl sulphate 2
solution and characterized using B.E.T surface area measurements, XRD and chemical analysis. The dependence of surface area on
concentration of staffing solution, temperature of hydrolysis, duration of boiling and calcination temperature were also studied. As the
boiling temperature, duration of boiling and calcination temperature increased, the surface area of TiO formed decreased significantly. 2
On increasing calcination temperature, the crystallite size of TiO also increased and gradually the phase transformation to rutile took 2
place. The onset and completion temperatures of rutilation were 700 and 10008C, respectively
Sugunan, S; Bindhu, Jacob; Binoy,Jose(Indian Journal of Chemistry, October , 1999)
[+]
[-]
Abstract:
The results of a detailed study of the propionylation of anisole over various medium and large pore zeolites such as H-ZSM-5, H-beta, H-Na-beta. H-mordenite. H-Y and H-RE- Y are presented and discussed. In addition, homogenous catalysts and amorphous Si02-Al2O3 are also included for comparison, The catalyst and process parameters are optimised to enhance the conversion of propionyl chloride(PC) and selectivity to 4-methoxypropiophenone(4-MOPP).
Girish Kumar,K; Remalakshmy,Poduval; Sareena, John; Pearl,Augustine(Department of Applied Chemistry, May 11, 2006)
[+]
[-]
Abstract:
A new PVC membrane sensor, which is
highly selective towards Ni (II) ions, has been developed
using a thiophene-derivative Schiff base as the
ionophore. The best performance was exhibited by the
membrane having the composition percentage ratio of
5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where
NaTPB is the anion excluder, sodium tetraphenylborate
and DBP is the plasticizing agent (dibutyl phthalate).
The membrane exhibited a good Nernstian response for
nickel ions over the concentration range of 1.0 10 1–
5.0 10 6M (limit of detection is 1.8 10 6 M) with a
slope of 29.5 1.0mV per decade of activity. It has a
fast response time of<20 s and can be used for a period
of 4 months with good reproducibility. The sensor is
suitable for use in aqueous solutions of a wide pH range
of 3.2–7.9. The sensor shows high selectivity to nickel
ions over a large number of mono-, bi- and trivalent
cations. It has been successfully used as an indicator
electrode in the potentiometric titration of nickel ions
against EDTA and also for direct determination of
nickel content in real samples – wastewater samples
from electroplating industries and Indian chocolates.