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.
Mohammed Yusuff, K K; Ahmed Yasir,Vakayil; Mohan Das,P N(Elsevier, International Journal of Inorganic Materials, August 12, 2001)
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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
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.
Mohammed Yusuff, K K; Mayadevi, S; Preetha, G Prasad(Taylor & Francis, May 5, 2003)
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Abstract:
Two series of transition metal complexes of Schiff bases derived from
quinoxaline-2-carboxaldehyde with semicarbazide (QSC) and furfurylamine
(QFA) were synthesised and characterised by elemental analyses,
molar conductance and magnetic susceptibility measurements, IR, electronic
and EPR spectral studies. The QSC complexes have the general
formula [M(QSC)Cl2]. A tetrahedral structure has been assigned for the
Mn(II), Co(II) and Ni(II) complexes and a square-planar structure for the
Cu(II) complex. The QFA complexes have the formula [M(QFA)2Cl2].
An octahedral structure has been assigned for these complexes. All of
the complexes exhibit catalytic activity towards the oxidation of 3,5-di-tert-butylcatechol (DTBC) to 3,5-di-tert-butylquinone (DTBQ) using
atmospheric oxygen. The cobalt(II) complex of the ligand QFA was
found to be the most active catalyst.
Mohammed Yusuff, K K; Mayadevi, S(Taylor & Francis, 1997)
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Abstract:
Some new transition metal complexes of the Schiff base
quinoxaline-2-car boxalidene-2-aminophenol (HQAP) have been
synthesized and characterized by elemental analyses, conductance
and magnetic measurements and IR and UV-Visible spectral studies.
The complexes have the following empirical formulae: [Mn(QAP121,
[Fe(QAPl2C1I, [Co(QAPl21, [Ni(QAP121 and [Cu(QAP121. A tetrahedral
structure has been assigned for the manganese(=), cobalt(II1,
nickel(II1 and copper(II1 complexes. For the iron(IIIl complex an
octahedral dimeric structure has been suggested
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.
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
Mohammed Yusuff, K K; Nampoori, V P N; Arun,V; Mathew, S; Robinson, P P; Jose,M(Elsevier, Journal of Dyes and Pigments, March 20, 2010)
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Abstract:
The Schiff base, 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine, was synthesized by the
condensation of 3-hydroxyquinoxaline-2-carboxaldehyde with 4-aminoantipyrine. HPLC, FT-IR and NMR
spectral data revealed that the compound exists predominantly in the amide tautomeric form and
exhibits both absorption and fluorescence solvatochromism, large stokes shift, two electron quasireversible
redox behaviour and good thermal stability, with a glass transition temperature of 104 oC. The
third-order non-linear optical character was studied using open aperture Z-scan methodology employing
7 ns pulses at 532 nm. The third-order non-linear absorption coefficient, b, was 1.48 x 10-6 cm W-1 and
the imaginary part of the third-order non-linear optical susceptibility, Im c(3), was 3.36x10-10 esu. The
optical limiting threshold for the compound was found to be 340 MW cm-2.
Mohammed Yusuff, K K; Varsha, Gopalakrishnan; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Digna, Varghese; Leeju, P; Jayachandran, V P(Elesvier,Tetrahedron Letters (2010), February 15, 2010)
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Abstract:
An efficient one-pot synthesis of two new heterocyclic perimidines 4-(2,3-dihydro-1H-perimidin-2-yl)-2-methoxyphenol and
2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine in good yields is presented. This methodology provides a simple, straightforward synthetic
route to these interesting classes of heterocycles. Crystal structure, solvatochromism and antibacterial activity of these organic compounds
are discussed.
Mohammed Yusuff, K K; Digna, Varghese; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan(International Union of Crystallography, Acta Crystallographica Section C ,Crystal Structure Communications, November 11, 2009)
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Abstract:
The Schiff base compounds N,N0-bis[(E)-quinoxalin-2-ylmethylidene]
propane-1,3-diamine, C21H18N6, (I), and N,N0-bis[(E)-
quinoxalin-2-ylmethylidene]butane-1,4-diamine, C22H20N6,
(II), crystallize in the monoclinic crystal system. These
molecules have crystallographically imposed symmetry.
Compound (I) is located on a crystallographic twofold axis
and (II) is located on an inversion centre. The molecular
conformations of these crystal structures are stabilized by
aromatic pye stacking interactions.
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
Xavier, K O; Chacko, J; Mohammed Yusuff, K K(Elsevier, Applied Catalysis A :General, September 4, 2003)
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Abstract:
Co(II), Ni(II) and Cu(II) complexes of dimethylglyoxime and N,N-ethylenebis(7-methylsalicylideneamine) have been synthesized in situ
in Y zeolite by the reaction of ion-exchanged metal ions with the flexible ligand molecules that had diffused into the cavities. The hybrid
materials obtained have been characterized by elemental analysis, SEM, XRD, surface area, pore volume, magnetic moment, FTIR, UV-Vis
and EPR techniques. Analysis of data indicates the formation of complexes in the pores without affecting the zeolite framework structure, the
absence of any extraneous species and the geometry of encapsulated complexes. The catalytic activities for hydrogen peroxide decomposition
and oxidation of benzyl alcohol and ethylbenzene of zeolite complexes are reported. Zeolite Cu(II) complexes were found to be more active
than the corresponding Co(II) and Ni(II) complexes for oxidation reactions. The catalytic properties of the complexes are influenced by their
geometry and by the steric environment of the active sites. Zeolite complexes are stable enough to be reused and are suitable to be utilized as
partial oxidation catalysts.