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Three new series, each of hemi-discoid oxovanadium(IV) and copper(II) complexes based on halogen-substituted ‘salphen’ type ligands; H2L = [N,N-Bis(4-n-alkoxysalicylidene)-4-fluoro/chloro/bromo-1,2...

This study applies positive matrix factorization (PMF) to 140 groundwater samples collected from four different Public Health Centers in North Brahmaputra basin, Assam, India. The aim of this technique is to identify and quantify the pollution sources (natural and anthropogenic) that affect the water quality. Multivariate statistical analysis, especially factor analysis, is successful in interpreting the water quality data, but it has some limitations: It does not consider analytical uncertainty and factor loadings may be negative which do not give a clear representation of the data. Therefore, we applied PMF to groundwater data and compared the results with those obtained from factor analysis. The major findings from the study are as follows: The first and the second factors show that the natural means are the main source of pollution where Cl, SO4, Ca, Mg, TA and TH were the main contributors from erosion and weathering of rocks. The Pb and NO3 from the third and the fourth factor, respectively, are the major sources of contamination from anthropogenic activities such as the use of fertilizers. The fifth factor results in Fe, As, Mn and Cr, suggesting that both natural and anthropogenic processes are the main pollution contributors. PMF exhibits a more realistic representation of data and helps us to better understand the major sources of contamination and the variation in groundwater quality data. Hence, it can be successfully used for the characterization of groundwater chemistry.

A new liquid crystalline salicylaldimine Schiff base having pendant hydroxymethyl ( CH2OH) groups and a series of lanthanide(III) complexes of the type, [Ln(LH)3(NO3)3] {Ln = La, Pr, Sm, Gd, Tb; LH=(E)-2-((1, 3-dihydroxy-2-(hydroxyl methyl) propan- 2-ylimino)methyl)-5-(hexadecyloxy) phenol} have been synthesised. The compounds were characterised by FT-IR, 1H NMR, 13C NMR, UV–Vis, and FAB-mass spectroscopy. Thermal behaviour of these compounds was studied using polarising optical microscopy (POM) and differential scanning calorimetry. The phase confirmation and molecular organization in the mesophase was ascertained by variable temperature powder X-ray diffraction (XRD) study. The ligand and the complexes both showed highly viscous smecticA and columnar mesophase, respectively. A bilayer self organization of the ligand molecules with interdigitation of the alkyl chains in the mesophase is proposed. Molecular organizations of the complexes in the mesophase involve arrangement of all the aliphatic chain pointing in same direction leading to lamellar columnar phase. The ligand showed an intense blue emission at 452 nm while the gadolinium(III) complex exhibited an intense emission at 458 nm (λex = 310 nm). The samarium(III) complex is a bright orange light emitter over a wide range upon UV irradiation.

Three new series of photoluminescent nickel(II) metallomesogens, [NiL]; H2L = N,N′-Bis(4-n-alkoxysalicylidene)-4-fluoro/bromo/chloro-1,2-diaminobenzene (n = 12, 14, 16) based on ‘salphen’ ligands h...

Hemi-disc shaped zinc(II) complexes of two new series of halogen-substituted ‘salphen’ type Schiff base ligands [ZnL]; H 2 L = [ N , N ′-Bis(4-n-alkoxysalicylidene)-4-fluoro/bromo-1,2-diaminobenzene] ( n = 12, 14, 16) have been synthesized and their mesomorphism and photophysical properties investigated. The ligands and zinc(II) complexes displayed columnar mesophases over a much wider temperature range. Depending on the halogen substitution at the ligand's spacer; different variant of columnar phases were exhibited by the ligands and the zinc(II) complexes. The ligands and the complexes displayed fluorescence at ambient temperature in the blue-green region with moderate to low intensity. Density functional theory (DFT) calculations indicated a distorted square-planar geometry around the zinc(II) center in the complexes. The coordinative unsaturation of the zinc(II) center in these complexes leads to interesting aggregation properties in a dilute solution of non-coordinating solvents. However, in coordinating solvent, axial coordination to the zinc(II) ion occurred leading to complete de-aggregation to monomer.

Mesomorphism induced by metal (VO2+, Ni2+, Cu2+ and Zn2+) coordination and its influence on the photophysical properties of a new series of symmetric “salphen”-type N,N-bis(4-n-alkoxysalicylidene)-4,5-dichloro-1,2-phenylenediamine ligands (n = 12, 14, 16) bearing highly electronegative spacer substituents and alkoxy arms of varied length have been investigated. The mesomorphism has been probed by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and variable-temperature powder X-ray diffraction (XRD). The Schiff base ligands are non-mesomorphic; however, coordination to NiII and ZnII ions induces columnar mesomorphism, this being stable down to room temperature in the latter case. Interestingly, the complexes of CuII and VOIV did not show any mesomorphism. The free ligands and the ZnII complexes are luminescent both in the condensed state and in solution, with emission maxima in the condensed state being significantly red-shifted with respect to those in solution. The energy-optimized structure of a representative ZnII complex was ascertained to be distorted square planar in a DFT study employing the GAUSSIAN 09 program. The ZnII and VOIV complexes exhibited solvatochromic effects, showing interesting aggregation behavior in the former case.

Silica nanoparticle embedded carbon 2D-nanocomposite material has been synthesized using a green procedure from a blue green alga, Scytonema guyanense, by direct pyrolysis at 600°C under inert atmosphere. The nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction and energy dispersive spectroscopy (EDS). Characteristic Si-O-Si vibrational absorptions at ~720 cm-1, ~790 cm-1 and ~1080 cm-1 attested the occurrence of silica in the nanocomposite material. Transmission electron microscopy (TEM) analysis revealed five-fold multiply twinned quasi spherical silica nanoparticles (~40 nm) embedded in ~3 nm thick carbon nanoflakes. The material exhibited weak luminescence at 340 nm. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging study showed moderate antioxidant activity of the material.

Biogenic synthesis of gold nanoparticles have been accomplished using dried biomass of two high altitude lichen species, collected from the alpine region of Eastern Himalaya in Arunachal Pradesh state of North East India, without addition of any external reducing or stabilizing chemicals. The nanoparticles were characterised by UV–visible, FT-IR spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained gold nanoparticles showed surface plasmon resonance (SPR) band at ~535 nm. The XRD study furnished evidence for the formation of face-centered cubic structure of gold nanomaterials. The nanoparticles produced with Acroscyphus sp. consisted of multiply twinned quasi-spherical and prismatic shapes while those accessed with Sticta sp. are exclusively multiply twinned. The biomatrix loaded gold nanomaterial exhibited pronounced antioxidant activity.

A series of four-coordinate d10-metal complexes of the type [ML2] {M = Zn, Cd, Hg; L = 4-nitro-2-((octadecylimino)methyl)phenol}, incorporating a new N-alkylated bidentate [N,O]-donor salicylaldimine Schiff base ligand, has been synthesized and characterized by elemental analyses, FT-IR, UV–Vis, 1H NMR and FAB-mass spectroscopies. The ligand is non-mesomorphic and devoid of any photoluminescence. The zinc(II) and cadmium(II) complexes displayed highly ordered mesophases reminiscent of soft crystals. The phases have been characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies. The complex of mercury(II) decomposed prior to melting. An orthogonal symmetry with a ‘herringbone’ array for the zinc complex and a primitive triclinic symmetry (p1) for the cadmium complex, respectively, has been proposed. The complexes exhibited fluorescence at room temperature, both in the solution and in the solid state, with emission maxima in the blue region. Density functional theory (DFT) calculations carried out using the gaussian 09 program at the B3LYP level revealed a distorted tetrahedral geometry around the metal center in all the complexes. Natural bond orbital (NBO) analysis suggested appreciable charge transfer from the ligand to the metal center in the complexes.

Six mixed ligand complexes, namely, [Co(acac)L 1 ] ( 1 ), [Fe(acac)L 1 ] ( 2 ), [Co(acac)L 2 ] ( 3 ), [Fe(acac)L 2 ] ( 4 ), [Co(acac)L 3 ] ( 5 ), and [Fe(acac)L 3 ] ( 6 ) (H 2 L 1 = NN / -bis(salicylidene)-trans 1,2 diaminocyclohexane, H 2 L 2 = NN / -bis(salicylidene)-1,2 phenylenediamine, H 2 L 3 = NN / -bis(salicylidene)-4-methyl-1,2-phenylenediamine) were synthesised and characterized using elemental analysis, IR spectra, UV–Vis spectra, mass spectra, magnetic susceptibility measurements, 1 H and 13 C NMR spectroscopy, thermogravimetric analysis. The molar conductance measurement confirmed the non-electrolytic nature of the complexes in DMF solution. Antioxidant activity of the complexes was studied using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging method. Biological studies of the complexes have been carried out in vitro for antimicrobial activity against some selected gram-positive and gram-negative bacteria. DFT calculations were performed using GAUSSIAN 09 program to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the complexes.

Multiwalled carbon nanotubes (MWCNTs) have been synthesized at low temperature on silicon substrates in a thermal chemical vapor reactor from ghee , clarified butter from cow׳s milk as the carbon source without using any catalyst. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses revealed bundles of micrometer long MWCNTs with an interlayer separation of 0.33 nm consisting of 25 concentric graphene sheets with outer and inner diameters of 27.45 and 13.68 nm, respectively. The powder X-ray diffraction (XRD) pattern showed a hexagonal structure of graphitic carbon with average crystallite size of 4.6 nm. The MWCNTs exhibited pronounced antioxidant activity.

A novel water soluble five coordinate oxovanadium(IV) complex, [VO(C16H15N4O8S)HSO4] incorporating cefuroxime, a cephalosporin group of antibiotic have been prepared from an interaction of vanadyl sulfate and cefuroxime in aqueous solution. The compound was characterized by Fourier transform infrared spectroscopy (FTIR), CHN microanalyses, ultraviolet-visible spectroscopy (UV-Vis), fast atom bombardment (FAB) mass spectrometry and thermogravimetric analysis (TGA). Density Functional Theory (DFT) computation using Gaussian 09 program at B3LYP level revealed a distorted square pyramidal energy optimized geometry for the vanadyl(IV) complex. The molecular docking studies show that the interaction between the vanadium complex and protein receptor, clathrin is dominated by hydrophobic forces. The experimental (1)H nuclear magnetic resonance (NMR) features of the analogous Zn(II) complex matched well with the theoretically computed values further affirming the distorted square pyramidal geometry for the vanadyl(IV) complex. Cyclic voltammetry revealed a metal centered single-electron oxidation-reduction response for VO(IV)/VO(V) couple. The antioxidant activity of the vanadium(IV)-complex vis-à-vis the antibiotic has been assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The vanadium complex showed comparatively better radical scavenging ability compared to the antibiotic cefuroxime. The antimicrobial activity of the compound has been assayed for five different microbial strains using minimum inhibitory concentration (MIC) method. Immunomodulatory studies carried out using phagocytosis index, myeloperoxidase release and cytokine assay indicated the vanadium(IV)-complex to be immunosuppressant. The cytotoxicity of the compound was evaluated by MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) reduction assay.

Liquid crystal-gold nanoparticle (GNP-LC) composite were accessed via covalent coupling of 4-mercaptophenol capped gold nanoparticles (GNP) and a carboxylic acid functionalised rod shaped mesomorphic Schiff base (LC). The Schiff base ligand and the composite both showed schlieren texture with distinct difference in phase transition temperature. The X-ray diffraction study suggested a smectic C mesophase for the compounds. The LC and GNP-LC, both exhibited room temperature photoluminescence when excited at 264nm.The transmission electron micrography revealed the composite to be nearly monodisphersed having almost spherical shape of ~ 2nm size. The composite material in addition to being mesomorphic exhibited pronounced AC conductivity in the semiconductor domain and antioxidant activity.

Human populace of Assam, India repeatedly exposed to high concentration of iron in groundwater results in adverse health effects like hemochromatosis, liver cirrhosis and siderosis. In the present study, human hair and nail analysis were carried out to establish a possible relationship between iron toxicity and its deposition among the residents. Nail and hair iron concentrations ranged from 28.2 to 1046μgg(-1) (n=114) and 26.5-838 (n=108)μgg(-1) levels, respectively, among all the study participants. The iron content of the groundwater (421-5340μgL(-1)) (n=64) used for drinking purposes was positively correlated with both nail (r=0.788, p0.0001) and hair (r=0.709, p0.0001) iron concentrations. Age- and sex-matched controls corresponding to each group were selected from population residing in other parts of the country where groundwater does not have excess iron. All the study groups included population drinking iron-contaminated water above the WHO/BIS limit (300µgL(-1)) for 5 years (Group 1), for more than 5-10 years (Group 2) and for more than 10 years (Group 3). Results suggested that the participants consuming groundwater exceeding the WHO limit of iron had significantly more iron accumulation than those using groundwater containing ≤300μgL(-1) iron (p0.01). There was statistically higher concentration of iron in the nail samples than the hair samples in all the study groups (p0.01). There was a positive correlation in iron concentration and the residence time of the participants (p0.01). Iron levels in the male participants were significantly higher than the female participants in the present study (p0.01). The current findings are sufficiently compelling to warrant more extensive study of iron exposure through drinking water and adverse effects to the human in the areas where iron concentration is high.

Zinc oxide (ZnO) nanorods were synthesized via a low-temperature thermal decomposition of zinc(II) acetylacetonate monohydrate, [Zn(C 5 H 7 O 2 ) 2 ].H 2 O. A relatively inexpensive surfactant, octadecylamine (C 18 H 37 NH 2 ) served both as a reaction solvent and a capping agent during the synthesis of ZnO nanorods. The synthesized nanorods were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, UV–visible, and photoluminescence (PL) studies. The XRD spectrum furnished evidence for the hexagonal wurtzite structure of ZnO. TEM images revealed the material to be rod shaped having diameter 30 nm and length 200 nm. The HRTEM image showed that the lattice fringes between the two adjacent planes are 0.244 nm apart, which corresponds to the interplanar separation of the (1 0 1) plane of hexagonal ZnO. The electron diffraction (ED) pattern confirmed the single crystalline nature of the nanorods. The PL spectrum showed two UV emissions at 356 nm (~3.48 eV) and 382 nm (~3.25 eV). ZnO nanorods also showed very weak blue bands at 445, 453 and 470 nm.

Biosynthesis of gold nanoparticles has been accomplished via reduction of an aqueous chloroauric acid solution with the dried biomass of an edible freshwater epilithic red alga, Lemanea fluviatilis (L.) C.Ag., as both reductant and stabilizer. The synthesized nanoparticles were characterized by UV-visible, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and dynamic light scattering (DLS) studies. The UV-visible spectrum of the synthesized gold nanoparticles showed the surface plasmon resonance (SPR) at around 530 nm. The powder XRD pattern furnished evidence for the formation of face-centered cubic structure of gold having average crystallite size 5.9 nm. The TEM images showed the nanoparticles to be polydispersed, nearly spherical in shape and have sizes in the range 5-15 nm. The photoluminescence spectrum of the gold nanoparticles excited at 300 nm showed blue emission at around 440 nm. Gold nanoparticles loaded within the biomatrix studied using a modified 2,2-diphenyl-1-picrylhydrazyl (DPPH) method exhibited pronounced antioxidant activity.

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), 1 H, 13 C 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 to16-OR show SmC phase at ∼113–118 °C and an unidentified SmX phase reminiscent of soft crystal at ∼77–91 °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.

Cupric oxide (CuO) nanoparticles have been successfully synthesized via low-temperature thermal decomposition of bis(dimethylglyoximato)copper(II) complex. The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and Raman spectroscopy. The powder XRD pattern furnished evidence for a monoclinic structure of CuO with average crystallite size 28.9 nm. The TEM image showed aggregation of some quasi-spherical nanoparticles. The Raman spectrum showed three characteristic modes of CuO which further affirmed the phasic purity of the obtained material. The CuO nanoparticles studied in an in vitro system using the modified diphenylpicrylhydrazyl (DPPH) method exhibited pronounced antioxidant activity.

Biosynthesis of gold nanoparticles has been achieved via reduction of an aqueous chloroauric acid solution with dried biomass of a freshwater epilithic green alga, Prasiola crispa , collected from a high altitude river ecosystem in Arunachal Pradesh state, India. The synthesized nanoparticles were characterized by UV–visible, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and DLS studies. The UV–visible spectrum of the synthesized gold nanoparticles showed a surface plasmon resonance (SPR) around 535 nm after 12 h. The powder XRD pattern furnished evidence for the formation of face-centered cubic structure of gold having average crystallite size 9.8 nm. The TEM images showed the nanoparticles to be nearly spherical in shape with sizes in the range of 5–25 nm.

Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2′-hydroxy acetophenone) glycinate, X = imidazole (im) 2 , benzimidazole (benz) 3, pyridine (py) 4 , hydrazine (hz) 5, 8-hydroxyquinoline (8-hq) 6 , pyrrolidine (pyrr) 7, piperidine (pip) 8 , and nicotinamide (nic) 9 ) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H 2 O)]·H 2 O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H 2 O)]·H 2 O , L = N-(2′-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2′ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO–LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

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...

Cubic CoO solid nanoparallelepipeds have been successfully synthesized via a low-temperature thermal decomposition of cobalt(II) acetylacetonate in the presence of a relatively inexpensive surfactant octadecylamine (C18H37NH2). Octadecylamine served both as reaction media and capping agent during the synthesis. The synthesized nanomaterial was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR and energy dispersive X-ray (EDX) studies. The XRD pattern furnished evidence for the face-centered cubic structure of CoO with average crystallite size of about 20 nm. The TEM images showed the nanoparticles to be monodispersed, parallelepiped shaped of 10—20 nm sizes. The electron diffraction pattern indicated polycrystalline nature of the synthesized material.

A novel photoluminescent room-temperature liquid-crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (Ln = La, Pr, Sm, Gd, Tb, Dy; LH = (E)-5-(hexyloxy)-2-[{2-(2-hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, (1)H and (13)C NMR, UV/Vis, and FAB-MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Col(h)) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (Col(L)) phase at around 120 °C with high thermal stability. Based on XRD results, different space-filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright-orange light (ca. 560-644 nm) and the terbium complex emitting green light (ca. 490-622 nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine-coordinate structure for the lanthanide complexes.

article i nfo Mixed metal hydroxide (MMH) is a purely inorganic viscosifier of montmorillonite suspensions, having environmental and thixotropic advantages over conventional viscosifiers. It was observed that the particle size distribution of the clay plays a crucial role in building up viscosity of clay-MMH suspensions. Two drilling clays, their separated b2 μm fractions and a pharmaceutical grade bentonite were studied. It was found that in a clay with 80% (w/w) particles below the 2 μm level the yield point (YP) rise of 2.5% (w/w) aqueous clay suspension is not stopped even on 0.3% (w/v) MMH treatment, whereas in a clay with less than 30% (w/v) particles below the 2 μm level the YP reaches a constant level of 8 lb/100 ft 2 after 0.1% MMH (w/v) treat- ment. When the b2 μm separated fraction is taken from the latter clay and hydrated it was found that YP rises even above the constancy level. On further homo-ionising this separated fraction to Na form and treating with MMH the YP rise was found still higher. When some carefully separated fraction containing a high amount of particles with less than b1 μm fraction was treated with MMH the YP rise was even higher. With the decrease of the particle size of the clay there is associated an increase of cation exchange capacity (CEC). Therefore, both CEC and particle size play a vital role in viscosity buildup which is due to the formation of an extended gel-network of clay and LDH particles at the prevailing alkaline pH of the system giving rise to high thixotropy. Finally, to reach a bench mark level of YP ≈ 20 lb/100 ft 2 with the latter clay one must opt for a base mud concentration of a minimum of 4% (w/v) aqueous system.

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 structure around each zinc(II...

Multiply twinned phase pure copper nanoparticles were successfully synthesized without any inert gas protection via a low-temperature thermal decomposition of a new precursor copper malonate, [CuCH 2 C 2 O 4 ]·2H 2 O in the presence of surfactant stabilizers oleylamine (C 18 H 35 NH 2 ) and triphenylphosphine ((C 6 H 5 ) 3 P). The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR and UV–vis spectroscopy. Freshly prepared copper nanoparticles showed surface plasmon resonance (SPR) around 574 nm. TEM studies revealed a five-fold multiply twinned morphology of decahedral shape for the copper nanoparticles. Powder XRD pattern furnished evidence for a face-centered cubic crystal structure of pure metallic copper having an average crystallite size of about 35 nm.

GNP-LC hybrid incorporating giant gold nanoclusters was accessed with tailor made liquid crystalline Schiff base bearing amine function as reactive end group without using any external reducing agent. The liquid crystal phase (smectic C) of the Schiff base remained unaltered in the hybrid material. The ligand and hybrid both exhibited interesting concentration-dependent fluorescence quenching of 9,10-diphenylanthracene when excited at 345 nm wavelength in dichloromethane solution. The GNP-LC hybrid exhibited reasonably good electrical conductivity showing an Arrhenius-type behaviour in the smectic mesophase and a tunnelling behaviour in the crystalline state.

A low-temperature synthesis of tricobalt tetraoxide, Co 3 O 4 nanoparticles was accomplished via thermal decomposition of a new precursor cobalt malonate, [CoCH 2 C 2 O 4 ]· 2H 2 O in presence of surfactant stabilizers oleylamine (C 18 H 35 NH 2 ) and triphenylphosphine ((C 6 H 5 ) 3 P). The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR and Raman spectroscopy. Powder XRD pattern furnished evidence for a face-centered cubic structure of Co 3 O 4 with average crystallite size of about 10 nm. TEM studies revealed Co 3 O 4 nanoparticles to be monodispersed, mostly cubic having sizes 4–12 nm. Electron diffraction pattern indicates polycrystalline nature of the synthesized material. Raman spectrum showed four characteristic peaks of Co 3 O 4 which further affirmed the phasic purity of the material.

Tricobalt tetraoxide nanoparticles have been successfully synthesized following a ‘bottom-up’ approach by surfactant-free thermal decomposition of cobalt(II)-tartrate complex obtained by a modified sol–gel route. The synthesized complex was characterized by Fourier transform infrared (FT-IR) spectroscopy, elemental and thermogravimetric-differential thermal analysis (TG–DTA). The nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman studies. The powder XRD pattern furnished evidence for a face-centered cubic structure of Co3O4. With the rise in calcination temperature from 400 through 500 to 600 °C, the average crystallite sizes of Co3O4 were found to increase from 28 through 36 to 46 nm. The TEM image revealed a faceted morphology of the as-synthesized Co3O4 nanoparticles. The high-resolution TEM image indicated the interplanar separation to be 0.28 nm which corresponds to the (220) plane in face-centered cubic Co3O4. The electron diffraction (ED) pattern showed single-crystalline nature of the synthesized nanoparticles. Raman spectrum showed four characteristic peaks of Co3O4 which further confirmed the phasic purity of the material.

A series of half-discoid [N2O2]-donor tetradentate alkoxy substituted salicylaldimine ligands, [N,N′-di- (4-n-alkoxysalicylidene)-4-Cl-l,2-diamino-benzene] (L; n = 12, 14, 16 and 18) have been prepared. The reaction of the ‘salphen’-type Schiff base ligand with Zn(OAc)2.4H2O afforded a series of mononuclear zinc(II) complexes. The ligands and the corresponding zinc(II) complexes were characterised by elemental analysis, Fourier transform infrared, proton nuclear magnetic resonance and ultraviolet-visible spectroscopy. Although the ligands are non-mesogenic, columnar mesomorphism is induced upon complexation with the metal. The p2gg symmetry of the rectangular columnar phase is confirmed by variable temperature powder X-ray diffraction study. Two ‘half-disc’-shaped molecules with four alkoxy legs are presumed to self-assemble via a dimeric interaction filling the space. In contrast to the ligands, the zinc(II) complexes all exhibited moderately intense green emission at room temperature both in solution an...

Zinc oxide nanocrystals were synthesized via thermal decomposition of a new precursor zinc malonate, [ZnCH2C2O4]·2H2O in the presence of surfactant stabilizers oleylamine (C18H35NH2) and triphenylphosphine ((C6H5)3P). The nanocrystals were characterized by X-ray diffraction, transmission electron microscopy, FT-IR and UV–visible spectroscopy. XRD pattern showed a hexagonal wurtzite structure of ZnO having average crystallite size of about 22 nm. The TEM image showed the nanocrystallites constituting the flower-like pattern to be of 25–55 nm sizes. The band gap luminescence was observed at 354 nm (∼3.50 eV) alongwith defect related blue emission at 450 nm (∼2.75 eV).

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.

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, 1H and 13C 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 by differential scanning calorimetry and polarised optical microscopy. The ligands are non-mesogenic, but upon coordination with vanadium(IV), exhibited enantiotropic rectangular columnar mesomorphism. The mesophase symmetry and the molecular organisation in the mesophases were confirmed by variable temperature powder X-ray diffraction study. An interesting phase behaviour exhibiting two types of rectangular columnar phases (Colr1 to Colr2) was observed for the vanadyl complexes, th...

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 functional theory calcula...

Novel photoluminescent salicylaldimine ligands condensed from 3 / , 3 / , 4 / , 4 / -tetraminobiphenyl and 4-substituted long alkoxy salicylaldehyde possessing two sets of tetradentate [N 2 O 2 ] 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, 1 H and 13 C 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 CH 2 Cl 2 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.

Cationic iron(III) complexes of the type [FeLn(H2O)2]NO3 (n = 1 or 2) were accessed from the interaction of Fe(NO3)3·9H2O with [N2O2] donor Schiff base (L) in 1:1 molar ratio. The Schiff base ligands were prepared from condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine or ethylenediamine in 2:1 molar ratio. Reaction of the aquated complexes with neutral N-donor molecules (X) viz. imidazole, benzimidazole and pyridine led to substitution of weakly held axial aquo groups affording new mixed ligand complexes, [FeLnX2]NO3. The compounds were characterized by elemental analyses, FT-IR, UV–Vis, solution electrical conductivity, FAB mass, 1H and 13C NMR (ligands only) spectroscopy. The thermal study provided unambiguous evidence for the occurrence of coordinated water in the complexes. Room temperature magnetic susceptibility measurements are consistent with high spin octahedral iron(III) complexes. Cyclic voltammetry revealed a quasi-reversible one electron redox response (ΔEp > 100 mV) assignable to Fe(III)/Fe(II) couple with negative half wave potential. The ground state geometries of the aquo complex, [FeL2(H2O)2]NO3 and pyridine complex, [FeL2(Py)2]NO3 were ascertained by density functional theory using dmol 3 program with BLYP functional.

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 the substituents but also on metal centre. The ligands all showed a smectic or nematic mesophase. However, nitro-substituted compounds with (n = 4) lacked any mesomorphism. Complexes (X = Cl, NO2, n = 4, 6 and M = Cu) exhibited smectic A phases. The vanadyl complexes did not show any mesogenicity. Variable temperature magnetic susceptibility measurements were carried out for the copper and vanadyl complexes. The complexes obey the Curie–Weiss law. Cyclic voltammetry showed a single electron quasireversible response for the complexes. Density functional the...

A series of hemi-disc shaped non-mesomorphic tetradentate salicylaldimine ligands [ N , N ′-di-(4-hexadecyloxysalicylidene)-l,2-diamino-benzene, N , N ′-di-(4-hexadecyloxysalicylidene)-4-Me-l,2-diamino-benzene, and N , N -di-(4-hexadecyloxysalicylidene)-4-NO 2 -l,2-diamino-benzene, (H 2 L)] were synthesized. Incorporation of nickel(II) in the tetradentate core via reaction with Ni(OAc) 2 ·4H 2 O afforded a series of four coordinate mesogenic NiL derivatives. The ligands and complexes were characterized by elemental analyses, FT-IR, UV–Vis, FAB-mass, 1 H and 13 C NMR (for ligands only). The mesomorphic behavior of the complexes were probed by polarizing optical microscopy, differential scanning calorimetry and powder X-ray diffraction technique. The non-mesogenic ligands upon coordination with nickel(II) exhibited monotropic/enantiotropic phase transition showing rectangular columnar mesophases (Col r ) with c 2 mm symmetry. A antiparallel dimeric association forming a disc-like arrangement in the mesophase is proposed on the basis of XRD-study. Solution electrical conductivity measurements are consistent with the non-electrolytic nature of the complexes. At room temperature with 330 nm excitation, the complexes showed blue emission both in the solid state (∼481 nm, Φ = 7%) and in solution (∼456 nm, Φ = 23%) while the ligands are non-emissive. The DFT study carried out at BLYP/DNP level revealed a distorted square planar structure for the nickel(II) complexes.

Thermal decomposition has been employed to access spherical nickel oxide (NiO) nanoparticles from a new precursor, nickel-salicylate, [Ni(C7H5O3)2(H2O)4]. Surfactants, triphenylphosphine ((C6H5)3P), and oleylamine (C18H35NH2) were added to control the particle size. The products were characterized by X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and thermogravimetric analysis. TEM images showed particles nearly spherical having sizes 5–15 nm. The magnetism of NiO nanoparticles was studied with a vibrating sample magnetometer. Due to smaller particle size and increased surface uncompensated spins, a superparamagnetic behavior is observed. The synthetic process is simple and affords high-purity material at a relatively lower calcination temperature.

A series of new photoluminescent hemidisc-shaped NiII Schiff-base complexes has been synthesized. The ligands and their complexes were characterized by FTIR and 1H and 13C NMR spectroscopy, FAB-MS and elemental analysis. The mesomorphic behaviour of the ligands and their complexes was probed by polarizing optical microscopy and differential scanning calorimetry. The molecular organization in the mesophase was determined by X-ray diffraction techniques. The ligands are nonmesogenic but their complexes exhibited thermally stable rectangular columnar (Colr) mesophases at about 227 °C. The complexes are blue-light emitters in solution (ca. 434 nm, Φ = 19 %) and in the solid state (ca. 469 nm, Φ = 7 %) at λex = 350 nm. A DFT study was carried out using DMol3 at the BLYP/DNP level to obtain a stable, optimized structure, which revealed a distorted square-planar geometry for the nickel complexes.

A series of bis[4-(n-alkoxy)-N-(4′-R-phenyl)salicylideneiminato]oxovanadium(IV) complexes (n = 6, 10, 14, 16, 18 and R = C3H7) were prepared and their mesogenic properties were investigated. The mesomorphic behaviors of the compounds were studied by polarized optical microscopy and differential scanning calorimetry. Ligands display SmA/SmC and unexpected nematic mesophases. The complexes bearing longer alkoxy carbon chain (n = 10, 14, 16, and 18) showed both monotropic or enantiotropic transitions with smectic A and high ordered smectic E phases. However, the complex with shorter carbon chain length (n = 6) showed monotropic transition with an unprecedented nematic (N) phase. A density functional theory study was carried out using DMol3 at BLYP/DNP level to obtain a stable optimized structure. A square-pyramidal geometry for the vanadyl complexes has been suggested. A νV=O stretching value of ∼970 cm−1 corroborated absence of any V = O ··· V = O interactions. Cyclic voltammetry revealed a quasireversible ...

Oxovanadium(IV)-Schiff-base complexes, [VOL2] {L = N,N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n = 10, 18; X = Cl, NO2}, have been synthesized from the interaction of vanadyl (VO2+) and the bidentate [N,O] donor in methanol/ethanol. The compounds were characterized by FT–IR, 1H- and 13C-NMR, FAB-mass spectra, elemental analyses, and solution electrical conductivity. Mesomorphic behavior of the ligands and their vanadyl complexes were probed by polarizing optical microscopy and differential scanning calorimetry. The compounds are thermally stable and exhibit enantiotropic smectic A mesomorphism over the temperature range of 57–231°C. The mesophase–isotropic transition temperatures for the complexes are much higher than the ligands. Melting and clearing points of the compounds did not show any definitive trend with regards to alkoxy chain length or electronegative substituent. Variable temperature magnetic susceptibility measurements of the vanadyl complexes clearly show the absence of exch...

A series of oxovanadium(iv) complexes of the type [VO(L)2], [L = N-(4-n-alkoxysalicylaldimine)-4-hexadecyloxyaniline, n = 8, 10, 12, 14, 16 or 18] have been synthesised and characterised by FT–IR, 1H NMR, 13CNMR, UV–Vis, and FAB mass and magnetic susceptibility measurements. The ligands are coordinated to the vanadyl ion in a bidentate fashion. The mesomorphic behaviour of the ligands and their vanadyl complexes was investigated by polarising optical microscopy and differential scanning calorimetry. The compounds were all highly thermally stable, and their mesomorphic properties were found to depend on the length of the carbon chain. Both the ligands and their higher homologue complexes exhibited a SmC mesophase. In the case of the lower homologues the ligands exhibited the SmC phase but their complexes a SmA mesophase. The mesophase–isotropic transition temperatures for the complexes were significantly higher than those of the ligands. Variable temperature magnetic susceptibility measurements on the vana...

Two new mixed-ligand iron(III) complexes, [Fe(L(n))(acac)(C(2)H(5)OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac)(3)] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H(2)L(1)) or 2-aminobenzoic acid (H(2)L(2)). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L(n))(acac)X] (n=1, 2; X=Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, (1)H and (13)C NMR spectroscopy. Room temperature magnetic susceptibility measurements (μ(eff)∼5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (ΔE(p)>100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential (E(1/2)) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level.