Prathapachandra Kurup, M R; Jessy, Emmanuel; Sithambaresan, M(November 3, 2011)
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Abstract:
The title compound, C11H9N3O2, exists in the E conformation
with respect to the azomethane C N bond, and has the keto
form. There are two independent molecules in the asymmetric
unit and each of these features a slight slanting of the pyridine
and furan rings, which form a dihedral angle of 14.96 (10) in
one of the molecules and 5.53 (10) in the other. The crystal
structure is stabilized by N—H O and N—H N hydrogen
bonds, weak C—H O and C—H N hydrogen bonds and
C—H interactions and – interactions [shortest
centroid–centroid distance = 3.7864 (15) A ° ].
Mohammed Yusuff, K K; Leeju, P; Arun,V; Manju, Sebastian; Varsha, Gopalakrishnan; Digna, Varghese(Crystallography Journals,Acta Crystallographica Section E ,Structure Reports, July 15, 2009)
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Abstract:
In the title molecule, C16H11N5, the mean planes of the
quinoxaline and indazole fragments form a dihedral angle of
10.62 (5). In the crystal, weak intermolecular N—H..........N
hydrogen bonds link the molecules into zigzag chains
extending in the [001] direction. The crystal packing also
exhibits pye interactions [centroid–centroid distances of
3.7080 (2) and 3.8220 (5) A ˚ ], which form stacks of the
molecules parallel to the a axis
Girish Kumar,K; Chowdary, K P R; Devala Rao, G(Indian Journal Of Pharmaceutical Sciences, January 8, 1999)
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Abstract:
Two simple and sensitive spectrophotometric methods (A and B)in the visible region have been developed for the determination of nimesulide in bulk and in dosage forms.Method A is based on the reaction of reduced nimesulide with nitrous acid followed by its coupling with phloroglucinol to yield an yellow colored azo dye with an absorption maximum of 400 nm and method B is based on the reaction of reduced nimesulide with p-dimethylamino benzaldehyde(PDAB) to form an yellow colored chromogen wiht an absorption maximum of 415 nm.When pharmaceutical preparations (Tablets and suspension) were analysed, the results obtained by the proposed methods are in good agreement with the labelled amounts and are comparable with the results obtained by a reported method.recovery in both the method is 98-101 %.
Mohammed Yusuff, K K; Arun, Vasudevan; Sreedevi, N; Robinson, P P; Manju, Sebastian(Elsevier,Journal of Molecular Catalysis A: Chemical 304 (2009) 191–198, February 7, 2009)
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Abstract:
Two new complexes, [MII(L)(Cl)(H2O)2]·H2O (where M=Ni or Ru and L = heterocyclic Schiff base, 3-
hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by
elemental analysis, FT-IR, UV–vis diffuse reflectance spectroscopy, FAB-MASS, TG–DTA, AAS, cyclic
voltammetry, conductance and magnetic susceptibility measurements. The complexes have a distorted
octahedral structure andwere found to be effective catalysts for the hydrogenation of benzene. The influence
of several reaction parameters such as reaction time, temperature, hydrogen pressure, concentration
of the catalyst and concentration of benzenewas tested. A turnover frequency of 5372 h−1 has been found
in the case of ruthenium complex for the reduction of benzene at 80 ◦C with 3.64×10−6 mol catalyst,
0.34 mol benzene and at a hydrogen pressure of 50 bar. In the case of the nickel complex, a turnover
frequency of 1718 h−1 has been found for the same reaction with 3.95×10−6 mol catalyst under similar
experimental conditions. The nickel complex shows more selectivity for the formation of cyclohexene
while the ruthenium complex is more selective for the formation of cyclohexane
Mohammed Yusuff, K K; Digna, Varghese; Arun, Vasudevan; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan(Crystallography Journals,Acta Crystallographica Section E ,Structure Reports, January 23, 2009)
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Abstract:
In the molecule of the title compound, C20H16N6, the central
C—C bond lies on a crystallographic inversion centre. The
quinoxalidine ring is nearly planar, with a maximum deviation
of 0.021 (2) A ˚ from the mean plane. The crystal structure is
stabilized by intermolecular C—H....N interactions, leading to
the formation of a layer-like structure, which extends along the
a axis
Mohammed Yusuff, K K; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan; Digna, Vasudevan(Elsevier, Dyes and Pigments 82 (2009) 268–275, January 18, 2009)
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Abstract:
A novel bisazomethine Schiff base was synthesised by the condensation of 3-hydroxyquinoxaline-2-
carboxaldehyde and 2,3-diaminomaleonitrile. 1H NMR, 13C NMR, HPLC and FT-IR studies revealed that
the compound exists in two major tautomeric forms. The Schiff base exhibits positive absorption and
fluorescent solvatochromism and displays dual fluorescence with large stoke shifts. Cyclic voltammetric
analysis of the compound in 1:1 methanol–THF was influenced by scan rate. Thermal analysis of the
compound was undertaken using TG–DTA and DSC
Kumar,K G; Augustine,P; John,S(Department of Applied Chemistry, June 21, 2007)
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Abstract:
A novel electrochemical sensor has been developed for the determination of nimesulide.
The sensor is based on the NIM- molybdophosphoric acid (MPA) as the electroactive
material in PVC matrix in presence of bis(2-ethyl hexyl) phthalate (BEP) as a
plasticizer. The sensor showed a fast, stable, near Nernstian response for 1 × 10-2 –1 ×
10-6 M NIM over the pH range 5 – 8 with a slope 55.6 ±0.5m V/decade and the response
time is < 45 s. Selectivity coefficient data for some common ions show negligible
interferences. The sensor was successfully applied for the determination of NIM in
tablet and the results obtained are in good agreement with those obtained by the official
method.
Girish Kumar,K; Pearl, Augustine; Sareena, John(Springer, August 29, 2009)
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Abstract:
The fabrication and electrochemical response
characteristics of two novel potentiometric sensors for the
selective determination of domperidone (DOM) are described.
The two fabricated sensors incorporate DOM–PTA
(phosphotungstic acid) ion pair as the electroactive material.
The sensors include a PVC membrane sensor and a carbon
paste sensor. The sensors showed a linear, stable, and near
Nernstian slope of 56.5 and 57.8 mV/decade for PVC
membrane and carbon paste sensors, respectively over a
relatively wide range of DOM concentration (1.0 9
10-1–1.0 9 10-5 and 1.0 9 10-1–3.55 9 10-6 M). The
response time of DOM–PTA membrane sensor was less than
25 s and that in the case of carbon paste sensor was less than
20 s.Auseful pH range of 4–6 was obtained for both types of
sensors. A detection limit of 7.36 9 10-5 M was obtained
for PVC membrane sensor and 1.0 9 10-6 M was obtained
for carbon paste sensor. The proposed sensors showed very
good selectivity toDOMin the presence of a large number of
other interfering ions. The analytical application of the
developed sensors in the determination of the drug in pharmaceutical
formulations such as tablets was investigated.
The results obtained are in good agreement with the values
obtained by the standard method. The sensors were also
applied for the determination ofDOMin real samples such as
urine by the standard addition method.
Description:
J Appl Electrochem (2010) 40:65–71
DOI 10.1007/s10800-009-9975-2
Sreekumar, K; Elizabeth, Chirackal Varkey(Wiley, July 20, 2010)
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Abstract:
The toluene diisocyanate based optically
active chiral polyurethanes were synthesized according to
the symmetry conditions. The noncentrosymmetric (both
charge asymmetry and spatial asymmetry) environment
were attained by the incorporation of the chiral units
(diethyl-(2R,3R)(þ)-tartrate) and donor-acceptor building
blocks in the main chain which induce a helical conformation
in the macromolecular chain. A series of optically
active polyurethanes containing chiral linkages in the
polymer back bone have been synthesized by using
DBTDL catalyst by incorporating the amido diols which
were obtained by the aminolysis of e-caprolactone by
using the diamines, diaminoethane, diaminobutane, and
diaminohexane respectively. The effect of incorporation of
the chiral molecule diethyl-(2R,3R)(þ)-tartrate on the properties
of polyurethanes was studied by changing the chromophores
and also by varying the chiral-chromophore
composition. Various properties of polyurethanes were
investigated by UV, Fluorescence, TG/DTA, XRD, polarimetric
techniques, Kurtz-Perry powder techniques, etc.
Description:
Journal of Applied Polymer Science, Vol. 119, 111–119 (2011)
Sreekumar, K(Indian academy of science, February 24, 2003)
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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)
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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)
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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)
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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)
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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.