Designer Ionic Liquid Crystals Based on Congruently Shaped Guanidinium Sulfonates
作者:Martin Butschies、Wolfgang Frey、Sabine Laschat
DOI:10.1002/chem.201101925
日期:2012.3.5
determine the influence of congruently shaped anions, in comparison with their spherical counterparts, on mesophase behaviour, which was investigated by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X‐ray diffraction (XRD). All the liquid crystalline salts exhibit smectic A mesophases with strongly interdigitated bilayer structures. The guanidinium sulfonate ion pairs
Role of Terminal Heterocyclic Ring on Mesomorphic Properties of Homologous Series*
作者:B. T. Thaker、B. S. Patel、D. B. Solanki、Y. T. Dhimmer、J. S. Dave
DOI:10.1080/15421400903290501
日期:2010.2.25
new homologous series of compounds with a heterocyclicring having sulfur and oxygen as a hetero atom derived from p-hydroxy acetophenone and alkoxy aniline containing cinnamate-azomethine as central linkages have been synthesized. viz. 4(furalacryloxy) α-methyl benzylidine-4′-alkoxy aniline and 4(thianylacryloxy) α-methyl benzylidine-4′-alkoxy aniline. The compound of both the series have been characterized
Studies of Calamitic Liquid Crystalline Compounds Involving Ester-Azo Central Linkages with a Biphenyl Moiety
作者:B. T. Thaker、Y. T. Dhimmar、B. S. Patel、D. B. Solanki、N. B. Patel、N. J. Chothani、J. B. Kanojiya
DOI:10.1080/15421406.2011.591677
日期:2011.10.14
Two mesogenic homologous series involving ester-azo central linkages with a biphenyl moiety have been synthesized, such as 4 '-[(4-n-alkoxyphenyl)diazenyl]biphenyl-4-ol (series I) and 4 '-[(4-n-alkoxyphenyl) diazenyl]-4-butoxy phenyl biphenyl-4-carboxylate (series II). Azobiphenyl of series I having a free hydroxyl group with strong hydrogen bonding exhibits a high-temperature enantiotropic smectic phase. Whereas in series II, compounds containing C-1-C-8 carbon atoms exhibit only a monotropic smectic phase and compounds with C-10, C-12, C-14, and C-16 atoms show an enantiotropic smectic phase. These compounds were characterized by elemental analysis, FT-IR, H-1-NMR, and mass spectral studies. The phase transition and mesogenicity of these substances were studied by polarizing optical microscopic and differential scanning calorimetric techniques. Their thermal stabilities and other characteristics are discussed.
Rod shaped oxovanadium(IV) Schiff base complexes: Synthesis, mesomorphism and influence of flexible alkoxy chain lengths
作者:Bishop Dev Gupta、Chitraniva Datta、Gobinda Das、Chira R. Bhattacharjee
DOI:10.1016/j.molstruc.2014.03.006
日期:2014.6
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. (C) 2014 Elsevier B.V. All rights reserved.
Molecular recognition at the air-water interface. Specific binding of nitrogen aromatics and amino acids by monolayers of long-chain derivatives of Kemp's acid
作者:Yasuhiro Ikeura、Kazue Kurihara、Toyoki Kunitake
DOI:10.1021/ja00019a035
日期:1991.9
Long-chain derivatives of Kemp's acid formed stable monolayers at the air-water interface, where the carboxylic acid groups produced the cyclic dimer species and served as a molecular cleft for specific binding of nitrogen aromatics and amino acids. The structure of the long-chain substituents was crucial for forming the cyclic dimer. Combinations of FT-IR, XPS, and UV spectroscopies of LB films and surface pressure-area isotherms revealed that substrates of complementary shape and functionality bound to the cleft mainly by hydrogen bonding. Phthalazine formed the 1:2 (substrate/amphiphile) complex, and enhanced binding of phthalazine (binding constant, 30 M-1) compared to that of quinazoline, quinoxaline, and pyridazine was ascribable to the proper location of nitrogen atoms within the molecule as well as smaller solubility in water. A more basic substrate, benzimidazole, bound to the monolayer 5 times more strongly probably in a form of the 1:1 complex. It is remarkable that significant substrate binding was attained even when the host monolayer and the substrates remained in exposure to the aqueous microenvironment. The monolayer of octadecanoic acid was not an effective receptor, implying that the convergent carboxylic acids were the intrinsic element of the molecular recognition.