Sreekumar, K; Rajesh Krishnan, G(Taylor & Francis, February 22, 2010)
[+]
[-]
Abstract:
Poly(amidoamine) dendrimers were synthesized on cross-linked aminomethyl polystyrene. Palladium
complexes of supported dendrimers prepared by ligand exchange method were reduced to dendrimernanoparticle
conjugates supported on polystyrene resin. The supported nanoparticles were used as
heterogeneous catalysts for the Suzuki coupling between aryl boronic acids and aryl halides. Various factors
affecting the catalysts performance were studied. Higher generation dendrimers gave well-defined
nanoparticles without agglomeration and these particles showed good catalytic performance
Mohammed Yusuff, K K; Mayadevi, S(Taylor & Francis, 1997)
[+]
[-]
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
Sreesha, Sasi; Prathapachandra Kurup, M R; Suresh, E(Springer, January 1, 2007)
[+]
[-]
Abstract:
The cobalt(III) complex, [Co(L)2(N3)2]2(ClO4)2, L being a Schiff base N-[phenyl(pyridin-2-yl)methylene]aniline has been synthesized and the crystal structure determined using X-ray crystallography. The complex crystallizes in triclinic system, space group P-1 with unit cell parameters a=10.9367(9) , b=18.0817(17) , c=20.1629(16) , α=111.341(2), β=91.622(2), γ=107.5030(10), V=3499.1(5) 3 and Z=2. It crystallizes with two independent molecules in the asymmetric unit. The two cobalt atoms are hexa-coordinate and have a distorted octahedral geometry, satisfied by four nitrogen atoms from two molecules of the Schiff base and two nitrogen atoms from the monodentate azide group. The perchlorate ions are non-coordinating.
Sreekumar, K; Sudheesh Kumar, K(Taylor & Francis, June 1, 2007)
[+]
[-]
Abstract:
Various polyurethanes containing photoactive bis(azo) and bis(o-nitrobenzyl)
groups in the main chain were synthesized by polyaddition reactions of diols such
as bis(4-hydroxyphenylazo)-2,20-dinitrodiphenylmethane, 4-hydroxy-3-methylphenylazo-
40-hydroxyphenylazo-2,20-dinitrodiphenylmethane and bis(4-hydroxy-3-
methylphenylazo)-2,20-dinitrodiphenylmethane with hexamethylene di-isocyanate
(HMDI), in dimethyl acetamide (DMAc) in the presence of di-n-butyltin dilaurate
(DBTDL) as catalyst. All of them were characterized by IR, UV-vis, 1H NMR and
13C NMR spectra and also by thermogravimetric analysis (TGA), differential scanning
calorimetry (DSC) and gel permeation chromatography (GPC).
Description:
International Journal of Polymeric Materials, 58:160–166, 2009
Girish Kumar,K; Karthikeyan, G; Mohanraj, K; Elango, K P(Pleiades, 2006)
[+]
[-]
Abstract:
A series of nonelectrolytic lanthanide(III) complexes,
[
ML
2
Cl
3
]
·
2
H
2
O, where M is lanthanum(III),
praseodymium(III), neodymium(III), samarium(III), gadolinium(III), terbium(III), dysprosium(III), and
yttrium(III), containing sulfamethoxazole ligand (L) are prepared. The structure and bonding of the ligand are
studied by elemental analysis, magnetic susceptibility measurements, IR,
1
H NMR,
TG
/
DTA
, X-ray diffraction
studies, and electronic spectra of the complexes. The stereochemistry around the metal ions is a monocapped
trigonal prism in which four of the coordination sites are occupied by two each from two chelating ligands, sulfonyl
oxygen, and nitrogen of the amide group and the remaining three positions are occupied by three chlorines.
The ligand and the new complexes were tested in
vitro to evaluate their activity against the bacteria
Escherichia
coli
and
Staphylococcus
aureus.
Prathapachandra Kurup, M R; Laly, K; Suja, Krishnan(Elsevier, November 10, 2009)
[+]
[-]
Abstract:
Five Mn(II) complexes of bis(thiosemicarbazones) which are represented as [Mn(H2Ac4Ph)Cl2]
(1), [Mn(Ac4Ph)H2O] (2), [Mn(H2Ac4Cy)Cl2]·H2O (3), [Mn(H2Ac4Et)Cl2]·3H2O (4) and
[Mn(H2Ac4Et)(OAc)2]·3H2O (5) have been synthesized and characterized by elemental analyses,
electronic, infrared and EPR spectral techniques. In all the complexes except [Mn(Ac4Ph)H2O], the
ligands act as pentadentate neutral molecules and coordinate to Mn(II) ion through two thione sulfur
atoms, two azomethine nitrogens and the pyridine nitrogen, suggesting a heptacoordination. While in
compound [Mn(Ac4Ph)H2O], the dianionic ligand is coordinated to the metal suggesting six coordination
in this case. Magnetic studies indicate the high spin state of Mn(II). Conductivity measurements reveal
their non-electrolyte nature. EPR studies indicate five g values for [Mn(Ac4Ph)H2O] showing zero field
splitting.
Prathapachandra Kurup, M R; Neema, Ani Mangalam(Elsevier, July 27, 2008)
[+]
[-]
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
Iron pillared Montmorillonite has been synthesised and it is then wet impregnated with vanadia with different vanadia
composition. These catalysts are characterised using conventional techniques such as XRD analysis,FTIR analysis and
surface area and pore volume measurements. Acidity is measured using spectrophotometric monitoring of adsorption of
perylene, thermogravimetric desorption of 2.6 dimethylpyridine and temperature programmed desorption of ammonia.
Activity studies are done in the liquid phase. It has been concluded that Lewis acidic sites are responsible for the benzylation
of toluene when the benzylating agent is benzyl chloride while Bronsted acidic sites are responsible when the reagent is
benzyl alcohol.
Sunajadevi, K R; Sugunan, S(Elsevier, October , 2004)
[+]
[-]
Abstract:
Chromia loaded sulfated titania has been synthesized via sol–gel route with different chromia loadings. These catalysts are characterized using conventional techniques such as XRD analysis, FTIR analysis, surface area and pore volume measurements, EDX, SEM and UV–Vis diffuse reflectance spectral analysis. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. Activity studies are done in the liquid phase. It has been concluded that Lewis acid sites are responsible for the benzylation of arenes with benzyl chloride.
A series of rare-earth neodymia supported vanadium oxide catalysts with various V205 loadings ranging from 3 to 15 wt.% were prepared
by the wet impregnation method using ammonium metavanadate as the vanadium precursor. The nature of vanadia species formed on the
support surface is characterized hy a series of different physicochemical techniques like X-ray diffraction (XRD). Fourier transform infrared
spectroscopy (FTIR). BET surface area, diffuse reflectance UV-vis spectroscopy (DR UV-vis), thermal analysis (TG-DTG/DTA) and SEM.
The acidity of the prepared systems were verified by the stepwise temperature programmed desorprion of ammonia (NH3-TPD) and found that
the total acidity gets increased with the percentage of vanadia loading. XRD and FT1R results shows the presence of surface dispersed vanadyl
species at lower loadings and the formation of higher vanadate species as the percentage composition of vanadia is increased above 9 wt.%.
The low surface area of the support. calcination temperature and the percentage of vanadia loading are found to influence the formation of
higher vanadia species. The catalytic activity of the V205-Nd203 catalysts was probed in the liquid phase hydroxylation of phenol and the
result show that the present catalysts are active at lower vanadia concentrations.
Mohammed Yusuff, K K; Anas, K(Elsevier, Applied Catalysis A :General 264 (2004) 213–217, December 25, 2003)
[+]
[-]
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.
Prathapachandra Kurup, M R; Suma, S; Sudarsana Kumar, M R; Siji, V L(Elsevier, February 26, 2010)
[+]
[-]
Abstract:
Eight new transition metal complexes of benzaldehyde-N(4)–phenylsemicarbazone have been synthesized
and characterized by elemental analyses, molar conductance, electronic and infrared spectral
studies. In all the complexes, the semicarbazone is coordinated as neutral bidentate ligand. 1H NMR
spectrum of [Zn(HL)2(OAc)2] shows that there is no enolisation of the ligand in the complex. The magnetic
susceptibility measurements indicate that Cr(III), Mn(II), Fe(III), Co(II) and Cu(II) complexes are
paramagnetic and Ni(II) is diamagnetic. The EPR spectrum of [Mn(HL)2(OAc)2] in DMF solution at 77K
shows hyperfine sextet with low intensity forbidden lines lying between each of the two main hyperfine
lines. The g values calculated for the [Cu(HL)2SO4] complex in frozen DMF, indicate the presence of
unpaired electron in the dx2−y2 orbital. The metal ligand bonding parameters evaluated showed strong
in-plane bonding and in-plane bonding. The ligand and complexes were screened for their possible
antimicrobial activities.
Description:
Spectrochimica Acta Part A 76 (2010) 22–28 doi:10.1016/j.saa.2010.02.035
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)
[+]
[-]
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
Bejoy, Thomas; Prathapan, Sreedharan; Sugunan, Sankaran(Elsevier, May , 2005)
[+]
[-]
Abstract:
The synthesis of dimethyl acetals of carbonyl compounds such as cyclohexanone, acetophenone, and benzophenone has successfully been carried out by the reaction between ketones and methanol using different solid acid catalysts. The strong influence of the textural properties of the catalysts such as acid amount and adsorption properties (surface area and pore volume) determine the catalytic activity. The molecular size of the reactants and products determine the acetalization ability of a particular ketone. The hydrophobicity of the various rare earth exchanged Mg–Y zeolites, K-10 montmorillonite clay, and cerium exchanged montmorillonite (which shows maximum activity) is more determinant than the number of active sites present on the catalyst. The optimum number of acidic sites as well as dehydrating ability of Ce3+-montmorillonite and K-10 montmorillonite clays and various rare earth exchanged Mg–Y zeolites seem to work well in shifting the equilibrium to the product side.
Prathapachandra Kurup, M R; Reena, T A(Springer, May 30, 2010)
[+]
[-]
Abstract:
A new semicarbazone, HL has been synthesized
from quinoline-2-carboxaldehyde and N4-phenyl-3-
semicarbazide and structurally and spectrochemically
characterized. 1H NMR, 13C NMR, IR and electronic
spectra of the compound are studied. The existence of keto
form in the solid state is supported by the crystal structure
and IR data. The compound crystallizes into an orthorhombic
space group P212121. Intra and intermolecular
hydrogen bonding interactions facilitates unit cell packing
in the crystal lattice
Description:
J Chem Crystallogr (2010) 40:927–932
DOI 10.1007/s10870-010-9765-z
Prathapachandra Kurup, M R; Seena, E B; Leji, Latheef(Elsevier, November 1, 2008)
[+]
[-]
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
Prathapachandra Kurup, M R; Seena, E B; Mini, Kuriakose(Springer, February 9, 2010)
[+]
[-]
Abstract:
Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-
3-hydroxy-2-naphthoylhydrazone (H2L)
have been synthesized and characterized. The complexes
were characterized by elemental analyses, IR, electronic
and EPR spectra. The oxovanadium(V) complex [VOL
(OCH3)] is crystallized in two polymorphic forms, denoted
by 1a and 1b, with space groups Pn21a and P 1, respectively.
Both have distorted square pyramidal structures.
Description:
Struct Chem (2010) 21:599–605
DOI 10.1007/s11224-010-9589-7
Prathapachandra Kurup, M R; Binu, Varghese; Sithambaresan, M; Suja, Krishnan; Sheeja, S R; Eringathodi, Suresh(Elsevier, 2011)
[+]
[-]
Abstract:
An interesting series of nine new copper(II) complexes [Cu2L2(OAc)2] H2O (1), [CuLNCS] ½H2O (2), [CuLNO3]
½H2O (3), [Cu(HL)Cl2] H2O (4), [Cu2(HL)2(SO4)2] 4H2O (5), [CuLClO4] ½H2O (6), [CuLBr] 2H2O (7),
[CuL2] H2O (8) and [CuLN3] CH3OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been
synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is
inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been
calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the
unpaired electron in the dx2 y2 orbital. The structure of the compound, [Cu2L2(OAc)2] (1a) has been
resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space
group P21/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with
one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane,
an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric
dimeric structure