Synthesis of imine-ester-linked benzothiazole mesogen containing liquid crystalline monomers with different terminal substituents

<p>A series of imine-ester-linked benzothiazole mesogen-based liquid crystalline (LC) monomers (<b>M1–M4</b>) having polymerizable methacrylate functional group as the terminal were designed and synthesized. These monomers were differentiated from each other by varying the terminal substituents (-H, -CH₃, -OCH₃, and -OCH₂CH₃) at the sixth position on the benzothiazole moiety. The chemical structures of the synthesized monomers were characterized and confirmed by spectroscopic techniques such as FTIR, ¹H NMR, and ¹³C NMR. Thermogravimetric analysis (TGA) was used to study the thermal properties of the investigated monomers. The ethoxy substituted monomer (<b>M4</b>) showed higher thermal stability compared with the other monomers. The mesomorphic behavior of all the monomers was studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). DSC and POM studies revealed that the monomer (<b>M1</b>) having no substituent at the sixth position on the benzothiazole ring exhibited both smectic and nematic mesophases, whereas -CH₃-, -OCH₃-, and -OCH₂CH₃-substituted compounds revealed only nematic mesophase.</p

EDS elemental analysis of different points on the Si+C pellet.

<p>EDS elemental analysis of different points on the Si+C pellet.</p

The schematic illustrating: Si+C embedded centrifugal thermite and a compacted graphite crucible assembly charged with the loaded green mixture A: before reaction (left), B: after reaction (right) while subjected to centrifugal force, the front and behind side of Si-C pellet is identified after reaction.

<p>The schematic illustrating: Si+C embedded centrifugal thermite and a compacted graphite crucible assembly charged with the loaded green mixture A: before reaction (left), B: after reaction (right) while subjected to centrifugal force, the front and behind side of Si-C pellet is identified after reaction.</p

FESEM micrographs and EDS elemental analyses of a Si-C pellet removed from the tube of a centrifugal thermite-assisted reaction: (a) overall topography, (b), (c), and (d) microstructure of typical points; (e) and (f) high magnification of region (d).

<p>FESEM micrographs and EDS elemental analyses of a Si-C pellet removed from the tube of a centrifugal thermite-assisted reaction: (a) overall topography, (b), (c), and (d) microstructure of typical points; (e) and (f) high magnification of region (d).</p

Schematic representation of forces acting on a moving particle during the hybrid centrifugal SHS process.

<p>Schematic representation of forces acting on a moving particle during the hybrid centrifugal SHS process.</p

XRD patterns of the Silicon-Carbon pellet after being exposed to centrifugal SHS.

<p>XRD patterns of the Silicon-Carbon pellet after being exposed to centrifugal SHS.</p

The pyrometer temperature reading and calculated values of viscosity versus time during the hybrid SHS process; d = 1.00E-04 m, n = 58 RPS, ρ_o = 7800 kgm^-3, ρ_m = 2700 kgm^-3, R = 2.50E-02 m.

<p>Region (i) shows a sudden temperature decline immediately after the reaction started (point A to B), region (ii) temperature drops to the melting point of Fe the point B to C. At region (iii), (iv) the crucible temperature stays steady for 1.5 s around Fe melting point, the solidification of the molten Fe starts at point E.</p

The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials

<p>A series of azo-ester linked mesogen containing liquid crystalline acrylate compounds <b>C1-C6</b> having different terminal groups (–F, –Cl, –Br, –OCH₃, –OC₂H₅ and –OC₃H₇) were successfully synthesised and characterised. The chemical structure, purity, thermal stability, mesophase behaviour and optical property of the synthesised compounds were investigated by different instrumental techniques. X-ray crystal structure showed that compounds <b>C1</b>, <b>C4</b> and <b>C5</b> exhibited more stable <i>E</i> configuration with two bulky group in the opposite side of the N=N double bond motifs. The fluoro-substituted derivative (<b>C1</b>) is connected by the R¹₂(5) type of C–H…O hydrogen bond motifs whereas the molecules of <b>C4</b>, and <b>C5</b> are connected to each other by means cyclic R²₂(8) type of C–H…O hydrogen bond motifs. Thermogravimetric study revealed that the investigated compounds exhibited excellent thermal stability. All the compounds showed enantiotropic liquid crystal (LC) phase behaviour and the mesophase formation was greatly influenced by the terminal substituents. Alkoxy (–OCH₃, –OC₂H₅ and –OC₃H₇) substituted compounds exhibited greater mesophase stability than those of halogen (–F, –Cl and –Br) terminated derivatives. UV-vis spectroscopic study revealed that the investigated compounds exhibited a broad absorption band around 300–420 nm with absorption maximum (<i>λ</i>_max) of nearly 370 nm.</p

Perovskite-Structured PbTiO₃ Thin Films Grown from a Single-Source Precursor

Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi­(μ₂-O₂CCF₃)₄(THF)₃(μ₃-O)]₂ (<b>1</b>), which was isolated in quantitative yield from the reaction of tetraacetatolead­(IV), tetrabutoxytitanium­(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex <b>1</b> has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, ¹H and ¹⁹F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from <b>1</b> by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV–visible spectrophotometry

Perovskite-Structured PbTiO₃ Thin Films Grown from a Single-Source Precursor

Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi­(μ₂-O₂CCF₃)₄(THF)₃(μ₃-O)]₂ (<b>1</b>), which was isolated in quantitative yield from the reaction of tetraacetatolead­(IV), tetrabutoxytitanium­(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex <b>1</b> has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, ¹H and ¹⁹F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from <b>1</b> by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV–visible spectrophotometry