Chitraniva Datta

Abstract A series of salicylaldimine-based copper (II) and oxovanadium (IV) complexes of the type [ML 2](M= Cu and VO, L= N, N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n= 4, 6; X= Cl, NO 2) have been synthesised. The mesomorphic ...

ABSTRACT A series of oxovanadium(IV) complexes of bidentate [N,O] donor Schiff-base ligands of the type [VO(L)(2)], [L = N-(4-n-alkoxysalicylaldimine)-4 '-octadecyloxyaniline, n = 8, 10, 12, 14, 16 and 18] have been synthesized. The compounds were characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), H-1, C-13 nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis), and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behavior of the compounds was studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The ligands and complexes are all thermally stable exhibiting smectic mesomorphism. The ligands 8-OR to 16-OR show SmC phase at,similar to 113-118 degrees C and an unidentified SmX phase reminiscent of soft crystal at similar to 77-91 degrees C whereas the complexes all showed SmA phases. Interestingly the complexes with C-10 and C-12 alkoxy chain length exhibited additionally SmC phases also. The melting points of the ligands linearly increases whereas mesophase to isotropic transition temperature decreases as a function of increasing carbon chain length of alkoxy arm while no trend was apparently noticeable for the complexes.

A new series of oxovanadium(IV) complexes of the type [VOL], L = N, N′-di-(4-n-alkoxysalicylidene)-4-Me-l,2-diamino-benzene (n = 14,16, 18) have been synthesised and their mesomorphic properties investigated. The compounds were characterised by Fourier transform infrared spectroscopy, H and C nuclear magnetic resonance spectroscopy, ultraviolet–visible spectroscopy, elemental analyses, solution electrical conductivity measurements and fast atom bombardment mass spectrometry. The phase behaviour of the compounds was examined

A series of new oxovanadium(IV) Schiff-base complexes of the type [VO(L)2], [L = N-(4-n-alkoxysalicylaldimine)-4′-dodecyloxyaniline, n = 6, 8, 16, and 18] have been synthesized. The compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, UV-Vis, FAB-mass, and magnetic susceptibility measurements. The mesomorphic behavior of the compounds was studied by polarized optical microscopy and differential scanning calorimetry. The compounds are all highly thermally stable exhibiting smectic mesomorphism. Non-electrolytic nature of the complexes was ascertained by solution electrical conductance measurements. Cyclic voltammetry revealed a quasireversible single-electron response for VO(V)/VO(IV) couple. A νV=O stretching mode at ∼970 cm−1 indicates absence of any intermolecular V=O ··· V=O interactions. Density functional theory study was carried out using DMol3 at BLYP/DNP level to determine energy optimized structure revealed a distorted square pyramidal geometry for the vanadyl complexes.

Two new liquid crystalline dinuclear copper(II) complexes of the type [Cu2L2 n], H2Ln = (E)-5-(hexadecyloxy)-2-((2-hydroxyethylimino) methyl) phenol(L) and (E)-5-(hexadecyloxy)-2-((2-hydroxypropylimino) methyl) phenol (L′), have been synthesised. The compounds were characterised by Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance, ultraviolet-visible spectroscopy, elemental analyses, solution electrical conductivity measurements and fast atom bombardment mass spectrometry. The phase behaviours of the compounds were examined by differential scanning calorimetry and polarised optical microscopy. Interestingly the ligand L showed a monotropic smectic A (SmA) mesophase at ∼75°C while the ligand L′ incorporating a methyl group in the spacer lacks any mesomorphism. The complexes were all found to exhibit a thermally stable enantiotropic SmA phase in the range ∼114–118°C. The ligands are blue light emitters with broad emission maxima at ∼469 nm. The density fu...

A series of salicylaldimine-based copper(II) and oxovanadium(IV) complexes of the type [ML2] (M = Cu and VO, L = N,N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n = 4, 6; X = Cl, NO2) have been synthesised. The mesomorphic behaviour of the ligands and their complexes was probed by polarising optical microscopy and differential scanning calorimetry. The formation of mesophases was dependent not only on the electronic or the steric factors of

ABSTRACT Novel photoluminescent salicylaldimine ligands condensed from 3/, 3/, 4/, 4/-tetraminobiphenyl and 4-substituted long alkoxy salicylaldehyde possessing two sets of tetradentate [N2O2] donor site and their binuclear zinc(II) complexes have been synthesized. The mesogenic and photophysical properties were investigated. The compounds were characterized by FT-IR, 1H and 13C NMR, UV–vis, elemental analyses, solution electrical conductivity measurements and FAB mass spectrometry. The mesomorphic behavior of these compounds was probed by differential scanning calorimetry and polarized optical microscopy. The ligand with six carbon chain length showed monotropic nematic mesomorphism at 128° C. However, the ligand with alkoxy tail of carbon length 12 showed enantiotropic SmC phase. The complexes are devoid of any mesomorphism. The low molar conductance values in CH2Cl2 indicate that the complexes are non-electrolytes. At 330 nm excitation, the ligand emits green light at ~ 516 nm (Φ = 30%) and ~ 549 nm (Φ = 16%) in solution and solid state, respectively. At similar excitation wavelength, the complexes exhibit blue light in solution at ~ 452 nm (Φ = 20%) and green light in solid state ~ 555 nm (Φ = 11%). The DFT calculations were performed using DMol3 program at BLYP/DNP level to ascertain the stable electronic structure of the complex.

A new zinc(II) bimetallomesogenic complex, [Zn2L2], of tridentate [ONO]-donor Schiff base ligand (L = N-(2-hydroxyethyl)-4-hexadecyloxysalicylaldimines) was synthesised and their mesomorphic and photoluminescence properties were investigated. The compounds were characterised by Fourier transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis) spectroscopy, elemental analyses and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behaviour of the complex was investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction (XRD) study. A rectangular or oblique columnar mesophase is conjectured on the basis of powder X-ray diffraction (PXRD) study. The complex is found to be blue light emitter in solution, in solid and in condensed states with broad emission maxima at ∼427–464 nm. The density functional theory (DFT) calculations revealed a distorted square planar struct...

ABSTRACT Novel four-coordinate copper(II) complexes of the type [CuL], L = N, N′-di-(4-hexadecyloxysalicylidene)-4-substituted(X)l,2-diamino-benzene (X = H, CH3, NO2) were synthesised. The compounds were characterised by elemental analyses, Fourier transform infrared spectroscopy, 1H, 13C nuclear magnetic resonance, ultraviolet–visible spectroscopy and fast atom bombardment mass spectrometry. The liquid crystalline properties were ascertained using polarised optical microscopy, differential scanning calorimetry and powder X-ray diffraction technique. The ligands are non-mesomorphic, but the complexes with methyl (CH3) or no substituent on the aromatic spacer showed rectangular columnar (Colr) mesophase and rectangular plastic columnar (Colrp) phase, respectively. An antiparallel dimeric association of half-disc shaped molecule forming a disc-like arrangement in the mesophase is proposed on the basis of X-ray diffraction study. The complex with nitro (NO2) substituent in the spacer linkage decomposes before melting precluding any mesomorphic study. The density functional theory calculations carried out using Gaussian 09 program at B3LYP level revealed distorted square planar geometry around the metal centre. The natural charges and electronic configuration of the atoms of the complexes and free ligand were evaluated by natural bond orbital analysis.

A series of oxovanadium(IV) complexes of bidentate [N,O] donor Schiff-base ligands of the type [VO(L)(2)], [L = N-(4-n-alkoxysalicylaldimine)-4 '-octadecyloxyaniline, n = 8, 10, 12, 14, 16 and 18] have been synthesized. The compounds were characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), H-1, C-13 nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis), and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behavior of the compounds was studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The ligands and complexes are all thermally stable exhibiting smectic mesomorphism. The ligands 8-OR to 16-OR show SmC phase at,similar to 113-118 degrees C and an unidentified SmX phase reminiscent of soft crystal at similar to 77-91 degrees C whereas the complexes all showed SmA phases. Interestingly the complexes with C-10 and C-12 alkoxy chain length exhibited additionally SmC phases als...