Browsing by Author "Sanyucta Kumari"

Now showing 1 - 12 of 12

Complexes of 3d metal ions of the Schiff-base, 4-hydroxy-N′-(4′-octadecyloxybenzylidene)benzohydrazide: Synthesis, spectral studies, crystal structure and magnetic interactions
(Elsevier Ltd, 2009) Angad Kumar Singh; Sanyucta Kumari; K. Ravi Kumar; B. Sridhar; Miroslaw Wrzecion; Jerzy Mroziński; T.R. Rao
A novel hydrazide-based mesogenic (nematic) Schiff-base, 4-hydroxy-N′-(4′-octadecyloxybenzylidene)benzohydrazide, (Hhodbbh) (abbreviated as HL3), was prepared and its structure studied by elemental analyses, mass, NMR and IR spectra and single crystal XRD (triclinic space group Pover(1, -) with Z = 2) techniques. The Schiff-base behaves as a non-deprotonated bi-dentate species in its metal complexes of the general formula, [M(HL3)2](OAc)2 [M = Mn, Co, Ni, Cu and Zn]. The IR and NMR spectral data imply bonding of HL3 species through amidic oxygen and azomethine nitrogen atoms. The MnII and CoII complexes show gradual decrease in the χMT product with lowering of temperature and negative Weiss constants characteristic of anti-ferromagnetic interaction. The MnII complex shows magnetic hysteresis loops at 2.0 K. © 2009 Elsevier Ltd. All rights reserved.
Complexes of some 3d metal ions of the Schiff's base, N,N′-di-4- (4′-pentyloxybenzoate) salicylidene-1″, 3″-diamino-2″- propanol: Synthesis and spectral studies
(2011) Angad Kumar Singh; Sanyucta Kumari; Pawan Raj Shakya; T.R. Rao
A nematogenic Schiff's base, N,N′-di-4-(4′-pentyloxybenzoate) salicylidene-l″, 3″-diamino-2″-propanol, (abbreviated as H2L6), was synthesized and its structure studied by elemental analyses, mass, NMR and IR spectra. The Schiff's base behaves as a dinegative hexa/tetradentate species in its metal complexes of the general formula, [ML6]n where MII, Co, Ni, Cu and Zn. Their structural characterizations were made by various spectroscopic techniques. © 2011 Elsevier B.V. All rights reserved.
Complexes of some rare earth metal ions of the mesogenic Schiff-base, N,N′-di-(4′-octyloxybenzoatesalicylidene)-l″, 8″-diamino-3″,6″-dioxaoctane: Synthesis and spectral studies
(2012) Sanyucta Kumari; Angad Kumar Singh; T.R. Rao
A mesogenic Schiff-base, N,N′-di-(4′- octyloxybenzoatesalicylidene)-l″,8″-diamino-3″, 6″-dioxaoctane; H 2dobsdd (H 2L 3), that nematogenic mesophase was synthesized and its structure studied by elemental analysis and FAB mass, NMR and IR spectra. The Schiff-base, H 2L 3, upon condensation with hydrated lanthanide(III) nitrates, yields Ln III complexes of the general composition [Ln 2(L 3H 2) 3(NO 3) 4](NO 3) 2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. The IR and NMR spectral data imply a bi-dentate of the Schiff-base through two phenolate oxygens in its zwitterionic form (as L 3H 2) to the Ln III ions, rendering the overall geometry of the complexes to seven-coordinated polyhedron - possibly distorted mono-capped octahedron. Among the metal complexes, only that of La III and Gd III are found to be mesogenic. © 2012 Elsevier B.V. All rights reserved.
Coordination of a mesogenic Schiff-base with MnII, CoII, NiII, CuII and ZnII: Synthesis, spectral studies and crystal structures
(Elsevier Ltd, 2008) Angad Kumar Singh; Sanyucta Kumari; T.N. Guru Row; Jai Prakash; K. Ravi Kumar; B. Sridhar; T.R. Rao
A novel mesogenic (nematic) Schiff-base, N,N′-di-4-(4′-pentyloxybenzoate)salicylidene diaminoethane, H2dpbsde (abbreviated as H2L5) was synthesized and its structure studied. The Schiff-base crystallizes in the non-centrosymmetric space group Pna21 with Z = 4, and the mesogenic isomorphous nickel and copper complexes, [NiL5]2 and [CuL5], in the centrosymmetric space group P21/c with Z = 4. The (L5)2- species coordinates to the metal ions through two phenolate oxygens and two azomethine nitrogens. Both the [NiL5]2 and [CuL5] complexes involve cis-MN2O2 planes; the former complex has a low-spin distorted square-pyramidal geometry with a Ni-Ni bonding of 3.337 Å and the latter, a square-planar geometry. © 2008 Elsevier Ltd. All rights reserved.
Crystal structure and ligational aspects of the mesogenic Schiff base, N,N′-di-(4-hexadecyloxysalicylidene)diaminoethane, with some rare earth metal ions
(Elsevier S.A., 2009) Sanyucta Kumari; Angad Kumar Singh; K. Ravi Kumar; B. Sridhar; T.R. Rao
A mesogenic Schiff base, N,N′-di-(4-hexadecyloxysalicylidene)diaminoethane, H2dhdsde (abbreviated as H2L1) that exhibit smectic-C (SmC) mesophase, was synthesized and its structure studied by elemental analyses, mass, NMR & IR spectra and single crystal XRD (triclinic space group P over(1, ̄) with Z = 1) techniques. Bi-dentate bonding of the Schiff base in the mesogenic LaIII complex was implied on the basis of IR & NMR spectral data. As per the spectral studies of the complexes, the Zwitterionic species of the ligand (H2L1) coordinates to LnIII ion through two phenolate oxygens rendering the overall geometry around the metal ion to distorted square antiprism (Ln = La, Pr, Nd, Sm, Eu) and monocapped octahedron (Ln = Gd, Tb, Dy, Ho). © 2009 Elsevier B.V. All rights reserved.
Crystal structure of 5-(furan-2-yl)-N-phenyl-1,3,4-oxadiazol-2-amine
(International Union of Crystallography, 2015) Santosh Paswan; Manoj K. Bharty; Sanyucta Kumari; Sushil K. Gupta; Nand K. Singh
The title compound, C12H9N3O2, was obtained as a cyclized oxadiazole derivative from substituted thiosemicarbazide in the presence of manganese(II) acetate. The furan ring is disordered over two orientations, with occupancies of 0.76 (2) and 0.24 (2). The dihedral angles between the central oxadiazole ring and the pendant phenyl ring and furan ring (major disorder component) are 3.34 (18) and 5.7 (6)°, respectively. A short intramolecular C - H⋯O contact generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N - H⋯N hydrogen bonds generate R 2 2[8] loops. The dimers are linked by C - H⋯π and π-π interactions [range of centroid-centroid distances = 3.291 (2)-3.460 (8) Å], generating a three-dimensional network.
Crystal structure of N'-[bis(ethylsulfanyl)methylidene]-2-hydroxy-4-methoxybenzohydrazide
(International Union of Crystallography, 2015) Paras Nath; Manoj K. Bharty; Rahul Chaurasia; Sanyucta Kumari; Sushil K. Gupta
In the title compound, C13H18N2O3S2, the amide group is in the plane of the benzoyl ring with a C - N - N - C torsion angle of 177.63(12)°. The two dithioate groups are in an anti conformation [torsion angles = 173.68(8) and -9.98(10)°]. An intramolecular N - H⋯O hydrogen bond is observed. In the crystal, an O - H⋯O hydrogen bond and a weak C - H⋯O contact involving the same acceptor atom generate an S(6) ring motif and give rise to chains along [010].
Ligational aspects of the hydrazide-based Schiff-base, N-(4″-pyridylcarboxamido)-4-(4′-hexyloxybenzoato)salicylaldimine towards some 3d metal ions and crystal structures of the Schiff-base and Zn(II) complex
(Elsevier Ltd, 2008) Angad Kumar Singh; Sanyucta Kumari; K. Ravi Kumar; B. Sridhar; T.R. Rao
A novel hydrazide-based mesogenic (nematic) Schiff-base, N-(4″-pyridylcarboxamido)-4-(4′-hexyloxybenzoato)salicylaldimine, Hpychbsal (abbreviated as H2L) was prepared and its structure studied by elemental analyses, mass, NMR and IR spectra and single crystal XRD (triclinic space group P over(1, ̄) with Z = 4) techniques. The Schiff-base behaves as a uninegative bi/tridentate species in its non-mesogenic complexes of the general formula, [M(HL)2] [M = Mn, Co, Ni, Cu and Zn] and as a dinegative tridentate species with Zn(II) in the distorted square-pyramidal complex, [ZnL · 2py], for which the crystal structure was solved (triclinic space group P over(1, ̄) with Z = 2). The IR and NMR spectral data imply bonding of HL- and L2- species through phenolate oxygen and/or amidic oxygen and azomethine nitrogen atoms. © 2008 Elsevier Ltd. All rights reserved.
Mesogenic lanthanoid metal complexes of a non-mesogenic Schiff-base, N,N′-di-(4-hexadecyloxysalicylidene)-l′,8′-diamino-3′,6′-dioxaoctane
(2009) Sanyucta Kumari; Angad Kumar Singh; T.R. Rao
A non-mesogenic Schiff-base, N,N′-di-(4-hexadecyloxysalicylidene)-l′,8′-diamino-3′,6′-dioxaoctane, H2dhdsdd (H2L2), was synthesized, structure studied by elemental analyses and mass, NMR and IR spectra and ligated to some LnIII metal ions that yielded mesogenic (SmA/N) LnIII complexes of the general composition, [Ln2(L2H2)3(NO3)4](NO3)2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L2H2) to the LnIII ions through two phenolate oxygens, rendering the overall geometry around LnIII to distorted mono-capped octahedron. © 2009 Elsevier B.V. All rights reserved.
Synthesis and spectral studies of the mesogenic Schiff-base, N,N′-di-(4′-pentyloxybenzoate) salicylidene-1,8-diamino-3,6-dioxaoctane and crystal structure of the Zn(II) complex
(Elsevier Ltd, 2008) Angad Kumar Singh; Sanyucta Kumari; K. Ravi Kumar; B. Sridhar; T.R. Rao
A novel Schiff-base, N,N′-di-(4′-pentyloxybenzoate)salicylidene-1,8-diamino-3,6-dioxaoctane (H2L4) with the mesogenic phase, nematic droplets, was prepared and its structure studied by elemental analyses and mass, NMR and IR spectra. The di-negative tetra-dentate bonding of the Schiff-base in the non-mesogenic complex, [ZnL4], as implied on the basis of IR and NMR spectral data, was confirmed in the crystal structure of the monomeric tetrahedral Zn(II) complex. As per the crystal structure of the complex, the dinegative species of the ligand, L42 -, coordinates to the Zn(II) ion through two phenolate oxygens and two azomethine nitrogens, rendering the overall geometry around Zn(II) to distorted tetrahedron. © 2007 Elsevier Ltd. All rights reserved.
Synthesis and spectral studies on some 3d metal complexes of a mesogenic ligand, N-(4′′′-n-butylphenyl)-4-(4′-hexyloxybenzoate) salicylaldimine
(2011) Angad Kumar Singh; Sanyucta Kumari; T.R. Rao
A mesogenic (nematic) Schiff's base, N-(4′′′-n- butylphenyl)-4-(4′-hexyloxy benzoate)salicylaldimine, Hbphbsal, (abbreviated as HL1), was synthesized and its structure studied by elemental analyses, mass, NMR and IR spectra. A series of mesogenic/non- mesogenic 3d metal complexes of the general formula, [M(L1) 2]n where MII = Mn, Co, Ni, Cu and Zn has been prepared and structures were studied by various spectroscopic techniques. Spectral studies imply coordination of the ligand (HL1) as uni-negative bi/tri-dentate species to the metal ions, rendering overall geometry to distorted square planar (in case of CuII complex) and octahedral geometry. The ESR spectra confirmed the presence of mixed copper-nitrogen and oxygen bonds in the chelate based on the g value. The CuII, CoII and NiII complexes were found to be mesogenic (nematic) and their transition, melting and clearing points deviated from the ligand upon complexation. © 2011 Elsevier B.V. All rights reserved.
Synthesis, structural studies of some lanthanide complexes of the mesogenic schiff-base, N,N′-di-(4′-octadecyloxybenzoate)salicylidene- 1″,3″-diamino-2″-propanol
(2014) Sanyucta Kumari
A mesogenic Schiff-base, N,N′-di-(4′-octadecyloxybenzoate) salicylidene-1″,3″-diamino-2″-propanol (H2L 5) was synthesized and its structure studied by elemental analyses and mass, NMR & IR spectra. The bidentate bonding of the Schiff-base in the mesogenic LaIII complex, as implied on the basis of IR & NMR spectral data. As per the spectral studies of the mesogenic (N/SmA) complexes, the Zwiterionic-species of the ligand coordinates (as L5H 2) to the LnIII ions through only two phenolate oxygens, rendering the overall geometry around LnIII to distorted mono-capped octahedron.