New mesogenic compounds possessing a biphenyl ester and ether moiety comprising 1,3-dimethylbarbituric acid: synthesis, characterisation and mesomorphic studies

New substituted derivatives of 5-vinyl-1,3-dimethylbarbituric acid were synthesised and evaluated for liquid crystal properties. Two sets of molecules were prepared. One end of all the molecules possesses the 1,3-dimethylbarbituric core. The first set comprises biphenyl ethers, 4a–n and the second set biphenyl esters, 5a–g. Liquid crystalline properties were investigated by POM and DSC techniques. All the compounds exhibited enantiotropic smectic A and nematic mesophases. The LC properties were found to depend on the spacer and terminal alkoxy- chain and alkoxy- ester moiety of the molecules. Smaller alkyl chain members showed a smectic phase, while higher alkyl chain members showed a nematic phase

Synthesis mesomorphic and theoretical studies of some new unsymmetrical dimeric ethers of 6-amino-1,3-dimethyluracil and biphenyl cores

New sets of unsymmetric calamitic molecules with uracil unit at one end and biphenyl core at another end were synthesized. Liquid crystal property of these molecules was investigated by POM and DSC techniques. All compounds exhibit LC property depending on the spacer and terminal alkoxy chain of the molecules. First set shows smectic phase in lower members and nematic phase appeared in higher members. The second set favour nematic liquid crystalline phase with respect to spacer alkyl chain length. Molecules are escaped from the planarity as a result disturbing the layer stacking leads to nematic phase in higher analogues. Theoretical studies have been performed for all the compounds and are found to be in agreement with the results of the current studies

Synthesis, molecular structures of alkyliminophenols and studies of their derivatives 1,3-oxazepine-4,7-diones

AbstractA series of alkyliminophenols (HOC6H4)CNCnH2n+1CH3 where n are even parity number ranging from 0 to 16 have been isolated and their molecular structures were studied. The molecular structure of 3-((dodecylimino)methyl)phenol has further been ascertained via the single-crystal X-ray diffraction analysis in which the compound possesses space group of P21/c. Crystal structures also revealed that the dodecyl chain in this molecule was fully extended in zig-zag form. The novel derivatives 1,3-oxazepine-4,7-diones with general formula (HOC6H4)CONCnH2n+1CHCH(CO)2 in which n are even parity numbers ranging from 2 to 18 have been synthesized from the reaction of 3-((alkylimino)methyl)phenol with maleic anhydride

Novel oxazepinedione-derived symmetric dimers: synthesis and mesophase characterisation of seven-membered heterocyclic compounds

<p>The synthesis and characterisation of three sets of symmetric dimeric compounds composed of seven-membered oxazepinedione heterocyclic rings were carried out. All the dimers possess the tetradecyl- (<i>n</i> = 14) alkyl side chain attached to the nitrogen atom of the oxazepinedione core. The oxazepinedione core in turn was connected with varied connecting spacers (<i>n</i> = 4, 6, 8, 10 and 12). The dimers were spectroscopically characterised by FT-IR, ¹H-NMR, ¹³C-NMR and elemental analysis techniques. The compounds were investigated for liquid crystalline properties using differential scanning calorimetry and polarising optical microscopy with heating assembly. The precursor imines <b>2a–e</b> itself started exhibiting liquid crystalline SmA/tilted hexatic mesophase. Further fusion of <b>2a–e</b> with maleic anhydride, succinic anhydride and phthalic anhydride gave the novel oxazepinedione-derived symmetric dimers <b>3a–e, 4a–e</b> and <b>5a–e</b> respectively. The dimers <b>3a–e</b> and <b>4a–e</b> did not exhibit any liquid crystal (LC) properties. However, the phthalic anhydride-fused oxazepinediones <b>5a–e</b> show monotropic nematic liquid crystalline phase. The results indicate that the formation of mesophase is dependent on the type of fused oxazepinedione ring.</p

Preparation, spectral and thermal properties of new Isoflavone derivatives: mesomorphic properties and DFT studies

<p>The four new homologous series of symmetric Isoflavon dimers were synthesised using varied alkyl/aryl diamines in linear sense. The chemical structures of the molecules were characterised by IR, NMR and CHNS analysis. Further, Liquid crystalline properties were verified using the combination of differential scanning calorimetry (DSC) and polarised optical microscope (POM). The molecular systems studied here reveal that LC property depends on the length of the middle connecting diamine spacer along with terminal alkyl spacer. The lower members favour to exhibit smectic A phase, whereas higher members exhibit nematic mesophase. The nature of LC property behaviours is supported by molecular geometries studied by DFT calculations.</p