Dipyrromethene-Cu(II) derivatives possessing two dodecane alkyl chains have been used for the modification of gold
electrodes. Electroactive host molecules have been incorporated into a lipophilic dodecanethiol SAM deposited onto
gold electrodes through hydrophobic and van der Waals interactions (embedment technique). The presence of
dipyrromethene-Cu(II) redox centers on the electrode surface was proved by cyclic voltammetry and Osteryoung
square-wave voltammetry. The Au electrodes incorporating redox active Cu(II)-dipyrromethene SAMs were used for
the direct voltammetric determination of paracetamol in human plasma.
The fabrication and analytical applications of two types of potentiometric
sensors for the determination of ketoconazole (KET) are described. The
sensors are based on the use of KET-molybdophosphoric acid (MPA) ion pair
as electroactive material. The fabricated sensors include both polymer membrane
and carbon paste electrodes. Both sensors showed a linear, stable and near
Nernstian slope of 57.8mV=decade and 55.2mV=decade for PVC membrane
and carbon paste sensors respectively over a relatively wide range of KET concentration
(1×10-2-5×10-5 and 1×10-2-1×10-6). The sensors showed a fast
response time of <30 sec and <45 sec. A useful pH range of 3–6 was obtained
for both types of sensors. A detection limit of 2.96 10 5M was obtained for
PVC membrane sensor and 6.91 10 6M was obtained for carbon paste sensor.
The proposed sensors proved to have a good selectivity for KET with respect to a
large number of ions. The proposed sensors were successfully applied for the
determination of KET in pharmaceutical formulations. The results obtained
are in good agreement with the values obtained by the standard method.
Spinel systems with the composition of Cu 1−x Zn x Cr 2 O 4 [x = 0 CCr, x = 0.25 CZCr-1, x = 0.5 CZCr-2, x = 0.75 CZCr-3 and x = 1 ZCr] were prepared by homogeneous co-precipitation method and were characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. Elemental analysis was done by EDX, and surface area measurements by the BET method. The redox behavior of these catalysts in cyclohexane oxidation at 243 K using TBHP as oxidant was examined. Cyclohexanone was the major product over all catalysts with some cyclohexanol. 69.2% selectivity to cyclohexanol and cyclohexanone at 23% conversion of cyclohexane was realized over zinc chromite spinels in 10 h.
PVC supported liquid membrane and carbon paste potentiometric sensors incorporating an Mn(III)-porphyrin
complex as a neutral host molecule were developed for the determination of paracetamol. The measurements were
carried out in solution at pH 5.5. Under such conditions paracetamol exists as a neutral molecule. The mechanism of
molecular recognition between the Mn(III)-porphyrin and paracetamol, leading to potentiometric signal generation,
is discussed.The sensitivity and selectivity toward paracetamol of carbon paste and polymeric liquid membrane electrodes
incorporating an Mn(III)-porphyrin host were compared. The applicability of these sensors to the direct
determination of paracetamol was checked by performing a recovery test in human plasma.
Mohammed Yusuff, K K; Pearly Sebastian, Chittilappilly; Sridevi, N(Elsevier,Journal of Molecular Catalysis A: Chemical 286 (2008) 92–97, February 5, 2008)
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Abstract:
Zeolite Y-encapsulated ruthenium(III) complexes of Schiff bases derived from 3-hydroxyquinoxaline-2-carboxaldehyde and 1,2-
phenylenediamine, 2-aminophenol, or 2-aminobenzimidazole (RuYqpd, RuYqap and RuYqab, respectively) and the Schiff bases derived from
salicylaldehyde and 1,2-phenylenediamine, 2-aminophenol, or 2-aminobenzimidazole (RuYsalpd, RuYsalap and RuYsalab, respectively) have
been prepared and characterized. These complexes, except RuYqpd, catalyze catechol oxidation by H2O2 selectively to 1,2,4-trihydroxybenzene.
RuYqpd is inactive. A comparative study of the initial rates and percentage conversion of the reaction was done in all cases. Turn over frequency
of the catalysts was also calculated. The catalytic activity of the complexes is in the order RuYqap > RuYqab for quinoxaline-based complexes and
RuYsalap > RuYsalpd > RuYsalab for salicylidene-based complexes. The reaction is believed to proceed through the formation of a Ru(V) species.
Sugunan, Sankaran; Binitha, N N(React Kinet.Catal.Lett.& Akademiai Kiado, March 27, 2008)
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Abstract:
Linear alkylbenzene sulfonic acid, the largest-volume synthetic surfactant, in addition to its excellent performance , is important due to its biodegradable environmental friendliness, as it has a straight chain and is prepared by the sulphonation of linear alkylbenzenes (LAB). To ensure environmental protection, the commercial benzene alkylation catalysts HF or AICI3 are replaced and we have developed a clean LAB production process using a pillared clay catalyst capable of not only replacing the conventional homogeneous catalyst, but also having high selectivity for the best biodegradable 2-phenyl LAB isomer .Pillared clay catalysts having high Bronsted acidity show efficient conversion in gas phase alkylation of benzene with 1-octene with a good 2-phenyl octane selectivity.
Sugunan, S; Nampoori, V P N; Radhakrishnan, P; Sanjay, G; Suja, H; Lyjo, Joseph K(Elsevier, June 28, 2008)
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Abstract:
Thermal diffusivity (TD) measurement on commercial K-10 and KSF montmorillonites was carried out by
photoacoustic technique. The TD of the montmorillonites after methylene blue adsorption changed with the
dye concentration. The repeatedly adsorbed samples showed a lesser TD than the single adsorbed samples.
After methylene blue adsorption the acid leached K-10 samples showed well defined changes in TD when
compared to the ordered KSF samples
Prathapachandra Kurup, M R; Neema, Ani Mangalam(Elsevier, July 27, 2008)
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Abstract:
Four oxovanadium and one dioxovanadium complex with 2-hydroxyacetophenone N(4)-
phenylthiosemicarbazone (H2L) which are represented as [VOLphen]·2H2O (1), [VOLbipy] (2),
[VOLdmbipy] (3), [VOL]2 (4) and [VO2HL]·CH3OH (5) have been synthesized and characterized by
elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes 1–4 the
ligand coordinates through phenolic oxygen, azomethine nitrogen and thiolate sulfur. But in complex
[VO2HL]·CH3OH, coordination takes place in thione form instead of thiolate sulfur. All the complexes
except [VO2HL]·CH3OH are EPR active due to the presence of an unpaired electron. In frozen DMF at 77 K,
all the oxovanadium(IV) complexes show axial anisotropy with two sets of eight line patterns
Sreekumar, Krishnapillai; Rajesh Krishnan, G(Eur. J. Org. Chem, August , 2008)
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Abstract:
This paper describes the first use of polystyrene-supported
poly(amidoamine) (PAMAM) dendrimers as heterogeneous
basic organocatalysts for carbon–carbon bond formation.
Polystyrene-supported PAMAM dendrimers of first, second
and third generations have been used as reusable base catalysts
in Knoevenagel condensations of carbonyl compounds
with active methylene compounds. The reactions proceed in short periods of time and with 100% selectivity. This novel
catalyst eliminates the use of aromatic and halogenated solvents,
as well as complex purification processes. The catalysts
can be recycled ten times.
This manuscript describes the first example of silver ion complex of a dendritic tetranitrile ligand catalyzed
one-pot three component Mannich reaction and 1,5-benzodiazepine synthesis. The catalyst can be separated from the
products by a change in the solvent. The catalyst is reusable.
Prathapachandra Kurup, M R; Alex, Punnoose; Manoj, E(Elsevier, October 17, 2008)
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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.
Prathapachandra Kurup, M R; Seena, E B; Leji, Latheef(Elsevier, November 1, 2008)
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Abstract:
A novel binuclear Ni(II) complex of salicylaldehyde 3-azacyclothiosemicarbazone (H2L) has been synthesized
and characterized by elemental analysis, IR and UV–Vis spectroscopy. The single crystal X-ray structure
of the complex shows that bridging occurs through thiolato sulfur and phenolic oxygen atoms.
Nickel centers in the complex have square planar and octahedral geometries
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.
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.
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.
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
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; 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; Varsha, Gopalakrishnan; Arun, Vasudevan; Manju, Sebastian; Leeju, P; Digna, Varghese(Crystallography Journals,Acta Crystallographica Section E ,Structure Reports, March 24, 2009)
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Abstract:
The asymmetric unit of the title compound, C11H8N4, contains
two independent molecules. In the crystal structure, intermolecular
N—H.....N hydrogen bonds link molecules into
ribbons extended in the [100] direction