Low Molecular Weight Calamitic Metallomesogens

Serrano, José Luís; Sierra, Teresa

doi:10.1002/9783527615094.ch3

Cited by 8 publications

(9 citation statements)

References 181 publications

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“…β-Diketones are key precursors for the synthesis of various five-membered heterocyclic and metallomesogenic derivatives. [2] The presence of hetero atoms such as N, O and S causes significant effects on dipole moment, polarisability and electronic nature of the molecules. Therefore, a large number of liquid crystals (LCs) have been derived from these heterocyclic cores.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of novel isoxazole-based banana liquid crystals from naturally occurring curcumin

2015

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Isoxazole-based bent-core liquid crystals (LCs) derived from naturally occurring curcumin were synthesised and their LC properties were investigated by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction techniques. Five compounds, including a branched alkyl chain derivative, were prepared and characterised. These derivatives exhibit enantiotropic mesophases. While lower homologues display widetemperature-range nematic phase, a longer-chain derivative 3d shows smectic C phase in addition to the nematic phase. The bent angle in these compounds is in between calamitic LCs and banana LCs. Therefore, the molecules escape from polar order packing observed in typical bent-core LCs. Increasing the length of alkyl chain reduces both melting and isotropic temperatures in the series. However, the compound with branched alkyl chains exhibits significant reduction in the nematic-isotropic temperature only. Detailed XRD experiments confirm the presence of the N phase in the lower homologues and SmC phase in a higher homologue.

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Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of novel isoxazole-based banana liquid crystals from naturally occurring curcumin

2015

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“…4,21 According to the literature mentioned above and Schiff base (azomethine) has been widely utilized as a linking group in the synthesis of many types of LC molecules. 22 Its derivative, salicylaldimine[N-(2-hydroxy-4-alkoxybenzylidene) aniline], possesses a quasi-six-membered ring resulting from intramolecular hydrogen (H)-bonding between the H-atom of the hydroxy group and the nitrogen (N)-atom of the imine linkage and thus exhibits more stability to moisture and heat than that of Schiff base analogues. With their synthetic versatility and ability to coordinate metals, they have also been applied in metallomesogens.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Functional Groups of Racemic Rodlike Schiff Base Mesogens on the Stabilization of Blue Phase in Binary Mixture Systems

Huang

Sie

et al. 2016

J. Phys. Chem. B

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Four series of rodlike racemic Schiff base mesogens possessing different alkyl chains and two types of linkages, ester and alkynyl linkages, were synthesized and applied to induce cubic blue phases (BPs) in simple binary mixture systems. The mesophases of these Schiff base mesogens were confirmed by variable-temperature X-ray diffraction and the characteristic texture from polarized optical microscopy (POM). In general, when chiral additive S-(+)-2-octyl 4-(4-hexyloxybenzoyloxy)benzoate (S811; 20-40 wt %) is added into the rodlike racemic salicylaldimine-based mesogens, the cubic BPs could be observed and its temperature range is larger than 20 K. The widest temperature range of the cubic BP (35 K) can be observed in the blending mixture composed of rodlike racemic salicylaldimine-based mesogen OH-TI possessing alkynyl linkage and 35-40 wt % S811. However, Schiff base mesogens possessing alkynyl linkage show a direct isotropic to chiral nematic transition when equal amount of chiral dopant is added. Notably, the termination temperature of BPs is very close to room temperature (ca. 35 °C) after 40.0 wt % S811 is added into the salicylaldimine-based mesogens possessing terminal alkyl chains and ester linkage. Interestingly, wide BPs (>30 K) can also be induced by adding chiral additive 1,4:3,6-dianhydro-2,5-bis[4-(n-hexyl-1-oxy)benzoic acid]sorbitol (ISO(6OBA)) with a high helical twisting power into the racemic Schiff base mesogen possessing ester linkage. Cubic BPI and BPII can be confirmed by reflectance spectra and POM. The results of reflectance spectra indicate that the binary mixture composed of salicylaldimine-based mesogens and S811 easily exhibits a supercooling effect and induces BPI. However, only BPII can be observed in all binary mixtures containing Schiff base mesogens. On the basis of our experimental results and molecular modeling, we suppose that the values of biaxiality, polarizability, and the dipole moment of molecular geometry are the main factors that affect BP stabilization.

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“…In these surfactants, the metal complex entity containing the central metal ion with its primary coordination sphere, acts as the head group and the hydrophobic entity of one or more ligands acts as the tail part. Surfactant metal complexes are expected to provide a wide range of interesting phenomena on aggregation in aqueous solution due to variations in charge numbers, size and extent of hydrophobicity through combination of the central metal and ligands [16]. The biological active compounds generally become more bacteriostatic and carcinostatic upon chelation with metal ions [17].…”

Section: Introductionmentioning

confidence: 99%

Structure and Biological Behaviors of Some Metallo Cationic Surfactants

Adawy

Khowdiary

2013

J Surfact & Detergents

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In this study, different cationic surfactants were prepared by esterification with bromoacetic acid of different fatty alcohols, i.e., dodecyl, tetradecyl and hexadecyl species. The products were then reacted with diphenyl amine, and the resulting tertiary amines were quaternized with benzyl chloride to produce a series of quaternary ammonium salts. The metallocationic surfactants were prepared by complexing the cationic surfactants with nickel and copper chlorides. Surface tension of these surfactants were investigated at different temperatures. The surface parameters including critical micelle concentration (CMC), maximum surface excess (C max ), minimum surface area (A min ), efficiency (PC 20 ) and effectiveness (p CMC ) were studied. The thermodynamic parameters such as the free energy of micellization (DG mic ) and adsorption (DG ads ), enthalpy (DH m ), (DH ads ) and entropy (DS m ), (DS ads ) were calculated. FTIR spectra and 1 H-NMR spectra were obtained to confirm the compound structures and purity. In addition, the antimicrobial activities were determined via the inhibition zone diameter of the prepared compounds, which were measured against six strains of a representative group of microorganisms. The results indicate that these metallocationic surfactants exhibit good surface properties and good biological activity on a broad spectrum of microorganisms.

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Low Molecular Weight Calamitic Metallomesogens

Cited by 8 publications

References 181 publications

Synthesis and characterisation of novel isoxazole-based banana liquid crystals from naturally occurring curcumin

Synthesis and characterisation of novel isoxazole-based banana liquid crystals from naturally occurring curcumin

Effect of the Functional Groups of Racemic Rodlike Schiff Base Mesogens on the Stabilization of Blue Phase in Binary Mixture Systems

Structure and Biological Behaviors of Some Metallo Cationic Surfactants

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