Prathapachandra Kurup, M R; Sheeja, S R; Sarika, Sivakumar; Neema, Ani Mangalam; Edward, R T Tiekink(Elsevier, June 23, 2009)
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Abstract:
Four hydrazone ligands: 2-benzoylpyridine benzoyl hydrazone (HBPB), di-2-pyridyl ketone nicotinoyl
hydrazone (HDKN), quinoline-2-carbaldehyde benzoyl hydrazone (HQCB), and quinoline-2-carbaldehyde
nicotinoyl hydrazone (HQCN) and four of their complexes with vanadyl salts have been synthesized and
characterized. Single crystals of HBPB and complexes [VO(BPB)(l2-O)]2 (1) and [VO(DKN)(l2-O)]2 ½H2O
(2) were isolated and characterized by X-ray crystallography. Each of the complexes exhibits a binuclear
structure where two vanadium(V) atoms are bridged by two oxygen atoms to form distorted octahedral
structures within cis-N2O4 donor sets. In most complexes, the uninegative anions function as tridentate
ligands, coordinating through the pyridyl- and azomethine-nitrogen atoms and enolic oxygen whereas in
complex [VO(HQCN)(SO4)]SO4 4H2O (4) the ligand is coordinated in the keto form. Complexes [VO(QCB)(
OMe)] 1.5H2O (3) and 4 are found to be EPR active and showed well-resolved axial anisotropy with
two sets of eight line pattern
Rapheal,P F; Manoj, E; Prathapachandra Kurup, M R(Elsevier, 2007)
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Abstract:
Ten copper(II) complexes {[CuL1Cl] (1), [CuL1NO3]2 (2), [CuL1N3]2 · 2/3H2O (3), [CuL1]2(ClO4)2 · 2H2O (4), [CuL2Cl]2 (5), [CuL2N3] (6), [Cu(HL2)SO4]2 · 4H2O (7), [Cu(HL2)2] (ClO4)2 · 1/2EtOH (8), [CuL3Cl]2 (9), [CuL3NCS] · 1/2H2O (10)} of three NNS donor thiosemicarbazone ligands {pyridine-2-carbaldehyde-N(4)-p-methoxyphenyl thiosemicarbazone [HL1], pyridine-2-carbaldehyde-N(4)-2-phenethyl thiosemicarbazone [HL2] and pyridine-2-carbaldehyde N(4)-(methyl), N(4)-(phenyl) thiosemicarbazone [HL3]} were synthesized and physico-chemically characterized. The crystal structure of compound 9 has been determined by X-ray diffraction studies and is found that the dimer consists of two square pyramidal Cu(II) centers linked by two chlorine atoms.
Prathapachandra Kurup, M R; Manoj, E; Rohith, John P; Nethaji, M; Alex, Punnoose(Elsevier, July 16, 2009)
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Abstract:
An unusual copper(II) complex [Cu(L1a)2Cl2] CH3OH H2O H3O+Cl (1a) was isolated from a solution of a
novel tricopper(II) complex [Cu3(HL1)Cl2]Cl3 2H2O (1) in methanol, where L1a is 3-(2-pyridyl)triazolo
[1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex
of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H2L1) was synthesized and physicochemically
characterized, while the formation of the complex 1a was followed by time-dependant monitoring
of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands
corresponding to O?Cu(II) charge transfer
Manoj, Easwaran potti; Prathapachandra Kurup, M R; Fun, Hoong-Kun(Elsevier, 2007)
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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.
microwave dielectric properties of ceramics based on Ba(Mgv3Ta(2-2x)t3W,t3Tixt3)O3 is investigated as a function of x. The
15 densification as well as dielectric properties deteriorate with increase in the substitution levels of (Ti 1,3W113)333 + at (Ta213)3.33+ site
16 in Ba(Mg113Ta213)03. The rt is approaching zero between x = 0.1 and 0.15 in Ba(Mg it3Ta(2-2,,.)t3W,it3Ti,Tt3)O3 where quality factor is
17 reasonably good (Qu x f = 80,000-90,000 GHz). The Ba(Mg1,3Ta(2_,013W,13Ti,,13)03 with x = 1.0 has e, = 15.4, rf= -25.1 ppm/
18 "C, Q„ x f = 35,400 GHz
Seven bis(ligand) Co(III) complexes {[CoL21] NO3 · H2 O (1), [CoL21] Cl · 2 H2 O (2),[CoL21] ClO4 (3), [CoL22] NO3 (4), [CoL22] Cl · 2 H2 O (5), [CoL23] Br · 2 H2 O (6), [CoL23] ClO4 · H2 O (7)} of three thiosemicarbazone ligands {pyridine-2-carbaldehyde-N(4)-p-methoxyphenyl thiosemicarbazone [HL1], pyridine-2-carbaldehyde-N(4)-2-phenylethyl thiosemicarbazone [HL2] and pyridine-2-carbaldehyde-N(4)-(methyl),N(4)-(phenyl) thiosemicarbazone [HL3]} were synthesized and physico-chemically characterized. All complexes are assigned octahedral geometries on the basis of spectral studies. The ligands deprotonate and coordinate by means of pyridine nitrogen, azomethine nitrogen, and thiolate sulfur atoms. The single crystal X-ray structures of HL3 and two nitrate compounds are discussed. The structural studies corroborate the spectral characterization.
Prathapachandra Kurup, M R; Sreesha, Sasi; Sithambaresan, M; Fun, H K(Elsevier, 2010)
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Abstract:
Four manganese(II) complexes Mn2(paa)2(N3)4 (1), [Mn(paa)2(NCS)2] 3/2H2O (2), Mn(papea)2(NCS)2 (3),
[Mn(dpka)2(NCS)2] 1/2H2O(4) of three neutral N,N donor bidentate Schiff bases were synthesized and physico-
chemically characterized by means of partial elemental analyses, electronic, infrared and EPR spectral
studies. Compounds 3 and 4 were obtained as single crystals suitable for X-ray diffraction. Compound 4
recrystallized as Mn(dpka)2(NCS)2. Both the compounds crystallized in the monoclinic space groups P21
for 3 and C2/c for 4. Manganese(II) is found to be in a distorted octahedral geometry in both the monomeric
complexes with thiocyanate anion as a terminal ligand coordinating through the nitrogen atom. EPR spectra
in DMF solutions at 77 K show hyperfine sextets with low intensity forbidden lines lying between each
of the two main hyperfine lines and the zero field splitting parameters (D and E) were calculated.
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
Prathapachandra Kurup, M R; Reena, T A(Springer, May 30, 2010)
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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)
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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
Prathapachandra Kurup, M R; Neema, Ani Mangalam(Elsevier, 2011)
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Abstract:
Six new copper complexes of di-2-pyridyl ketone nicotinoylhydrazone (HDKN) have been synthesized.
The complexes have been characterized by a variety of spectroscopic techniques and the structure of
[Cu(DKN)2]·H2O has been determined by single crystal X-ray diffraction. The compound [Cu(DKN)2]·H2O
crystallized in the monoclinic space group P21 and has a distorted octahedral geometry. The IR spectra
revealed the presence of variable modes of chelation for the investigated ligand. The EPR spectra
of compounds [Cu2(DKN)2( -N3)2] and [Cu2(DKN)2( -NCS)2] in polycrystalline state suggest a dimeric
structure as they exhibited a half field signal, which indicate the presence of a weak interaction between
two Cu(II) ions in these complexes