Sugunan, S; Nishamol, K(Indian Journal of Chemistry, May , 2002)
[+]
[-]
Abstract:
The liquid-phase Friedel-Crafts acylation of toluene using benzoyl chloride as benzoylating agent has heen carried out over Nix, Mn(l-x)Fe2 O4 (x=O, 0.2, 0.4, 0.6, 0.8 and 1.0) type systems under different reaction conditions. It is observed that the systems with high 'x' values are effective for the conversion of BOC and the selective formation of 4-MBP. Selectivity for 4-MBP over MnFe2O4 is more than 90% under the optimized reaction conditions. Sites of moderate acidity is effective in calalyzing the benzoylation reaction.
Manoj, Easwaran potti; Prathapachandra Kurup, M R; Fun, Hoong-Kun(Elsevier, 2007)
[+]
[-]
Abstract:
A novel N4O coordination mode offers carbohydrazone ligands as a building block for interesting frameworks through self-assembly. Bridging mode of oxygen of bis(2-benzoylpyridine ketone) carbohydrazone (H2L) with metal centers facilitates the formation of the macrocyclic molecular square [Zn(HL)]4(BF4)4 · 10H2O, offers wide range of applications for carbohydrazones.
Anantaraman, R; Sugunan, S(Indian Journal of Chemistry, August , 1982)
[+]
[-]
Abstract:
Kinetics of mercuric chloride catalysed solvolysis of benzyl chloride have been studied in water. 10% aq. ethanol, 10,20 and
30% aq. acetone and 20% aq. DMSO. The results confirm the operation of a mass law effect.
Sreekumar, K(Taylor and francis, October 20, 2003)
[+]
[-]
Abstract:
Polymer materials find application in optical storage technology,
namely in the development of high information density and fast access type
memories. A new polymer blend of methylene blue sensitized polyvinyl alcohol
(PVA) and polyacrylic acid (PAA) in methanol is prepared and characterized
and its comparison with methylene blue sensitized PVA in methanol and
complexed methylene blue sensitized polyvinyl chloride (CMBPVC) is presented.
The optical absorption spectra of the thin films of these polymers
showed a strong and broad absorption region at 670-650 nm, matching the
wavelength of the laser used. A very slow recovery of the dye on irradiation was
observed when a 7:3 blend of polyvinyl alcohol/polyacrylic acid at a pHof 3.8
and a sensitizer concentration of 4.67 10 5 g/ml were used. A diffraction
efficiency of up to 20% was observed for the MBPVA/alcohol system and an
energetic sensitivity of 2000 mJ/cm2 was obtained in the photosensitive films
with a spatial frequency of 588 lines/mm.
Prathapachandra Kurup, M R; Sheeja, S R; Neema, Ani Mangalam(Elsevier, 2010)
[+]
[-]
Abstract:
Mn(II) complexes derived from a set of acylhydrazones were synthesised and characterized by elemental
analyzes, IR, UV–vis and X-band EPR spectral studies as well as conductivity and magnetic susceptibility
measurements. In the reported complexes, the hydrazones exist either in the keto or enolate form, as evidenced
by IR spectral data. Crystal structures of two complexes are well established using single crystal
X-ray diffraction studies. In both of these complexes two equivalent monoanionic ligands are coordinated
in a meridional fashion using cis pyridyl, trans azomethine nitrogen and cis enolate oxygen atoms positioned
very nearly perpendicular to each other. EPR spectra in DMF solutions at 77 K show hyperfine sextets
and in some of the complexes the low intensity forbidden lines lying between each of the two
hyperfine lines are also observed
The influence of the chemical composition and silylation of mesoporous MCM-41 materials on the photochromic
behaviour of adsorbed spiropyran (BIPS) and 6-nitrospiropyran was studied. Upon incorporation, the spiropyrans
underwent ring opening to form either zwitterionic merocyanine or its corresponding O-protonated form. In all
silica MCM-41 or in the MCM-41 containing aluminium, the O-protonated merocyanine was predominantly
formed. In the case of MCM-41 modified by silylation of the OH groups, a mixture of zwitterionic merocyanine
and spiropyran was present. The photochromic response was studied by means of steady-state irradiation and by
laser flash photolysis. Steady-state irradiation (λ > 450 nm) of the solid samples gives rise in all cases to an intensity
decrease of the absorption bands corresponding to either the protonated or the unprotonated merocyanine form
(reverse photochromism). In contrast, laser flash photolysis at 308 nm of spiropyrans supported on silylated
MCM-41 allows observation of the photochemical ring opening of residual spiropyran to the corresponding
zwitterionic form (normal photochromism).
Prathapachandra Kurup, M R; Jessy, Emmanuel; Sithambaresan, M(November 3, 2011)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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)
[+]
[-]
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.