scholarly journals Effect of Lateral Substitution on the Electronics and Phase Transitions of Stilbazoles, Benzoic Acids, Phenols, and Hydrogen Bonded Mixtures

2015 ◽  
Vol 2015 ◽  
pp. 1-14
Author(s):  
Jeremy R. Wolf
Keyword(s):  
Liquid Crystalline ◽  
Benzoic Acids ◽  
Minimal Effect ◽  
Melting Points ◽  
Effective Technique ◽  
Liquid Crystalline Phases ◽  
The Individual ◽  
Bonded Complexes ◽  
Hydrogen Bonded

The preparation and characterization of laterally substituted 4-alkoxy-stilbazoles, 4-alkoxy-benzoic acids, and 4-alkoxy phenols and hydrogen bonded heterodimeric mixtures of these compounds are reported. Lateral substitution has a minimal effect on the ring electronics of 4-alkoxy benzoic acids and 4-alkoxy phenols; however the ring electronics of stilbazole units is extremely sensitive to lateral substitution. While lateral substitution is an effective technique for lowering the melting points of both hydrogen bonded complexes and their individual components, its effect on the electronics of stilbazoles and steric disruption of both intermolecular hydrogen bonding and molecular packing in the solid state disrupts the formation of liquid crystalline phases in both the individual components and hydrogen bonded complexes.

Separation and Characterization of Standard Propoxyphene Diastereomers and Their Determination in Pharmaceutical and Illicit Preparations

1981 ◽  
Vol 64 (4) ◽  
pp. 875-883
Author(s):  
Shiv K Soni ◽  
Daniel Van Gelder
Keyword(s):  
High Pressure ◽  
Optical Isomers ◽  
Gold Chloride ◽  
Melting Points ◽  
Eutectic Melting ◽  
Racemic Mixtures ◽  
The Individual ◽  
Isomeric Mixtures ◽  
Asymmetric Carbon

Abstract Due to the existence of 2 asymmetric carbon atoms in: the propoxyphene molecule, there are 4 diastereomers: alpha dextro, alpha levo, beta dextro, and beta levo. Only α-d-propoxyphene is included under the federal Controlled Substances Act. Baseline separations of propoxyphene from various incipients (aspirin, caffeine, phenacetin, and acetaminophen) present in pharmaceutical and illicit preparations, and between the alpha and beta diastereomers, were achieved by high pressure liquid chromatography. The column eluant was collected and propoxyphene was extracted. The optical isomers were differentiated and characterized by melting points and by chemical microcrystalline tests. Using hot stage thermomicroscopy, the eutectic melting points of binary isomeric mixtures of propoxyphene bases and salts were found to be depressed about 10° and 15-30°C, respectively, below the individual isomer melting points. The characteristic microcrystals formed with the alpha racemic mixtures by using a glycerin-aqueous gold chloride reagent were not produced by the beta racemic mixtures.

Characterization of some mesogenic alkyl 1-thioglycosides

2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Solid State ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
Liquid Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

Synthesis and characterization of novel dibenz[a,c]anthracenedicarboxythioimides: the effect of thionation on self-assembly

RSC Advances ◽  
2016 ◽  
Vol 6 (82) ◽  
pp. 78784-78790 ◽  
Author(s):  
Katie. M. Psutka ◽  
Kenneth E. Maly
Keyword(s):  
Self Assembly ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Crystalline Phases ◽  
Liquid Crystalline Phases ◽  
Self Association

The effect of thionation on the formation of columnar liquid crystalline phases of dibenzanthracenedicarboximides as well as their self-association in solution is described.

Synthesis and Characterization of Stilbene Derivatives for Possible Incorporation as Smart Additives in Polymers Used as Packaging Films.

1997 ◽  
Vol 50 (4) ◽  
pp. 425 ◽  
Author(s):  
Gary M. Day ◽  
Owen T. Howell ◽  
Michael R. Metzler ◽  
Paul D. Woodgate
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Packaging Films ◽  
Multiple Phase ◽  
Liquid Crystalline Phases ◽  
Crystal Properties ◽  
Stilbene Derivatives

Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.

Mixed-dimer formation in binary systems of 4-substituted benzoic acids and structure considerations

2008 ◽  
Vol 86 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Maren Roman ◽  
Annett Kaeding-Koppers ◽  
Peter Zugenmaier
Keyword(s):  
Benzoic Acid ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Binary Systems ◽  
Benzoic Acids ◽  
Dimer Formation ◽  
Crystalline Phases ◽  
Cholesteric Phase ◽  
Liquid Crystalline Phases ◽  
Substituted Benzoic Acids

The phase behavior of binary systems of 4-substituted benzoic acids is governed by the formation of mixed dimers. This study was conducted to determine the effect of the components’ structural difference on mixed-dimer formation in crystalline and liquid-crystalline phases. The phase diagrams of two systems, with 4-[(S)-(–)-2-methylbutoxy]benzoic acid (MBOBA) as one component and 4-(hex-5-enoxy)benzoic acid (HOBA) and 4-(dec-9-enoxy)benzoic acid (DOBA), respectively, as the second component, were determined by differential scanning calorimetry, polarized-light microscopy, and X-ray diffraction. The MBOBA-HOBA system exhibited a cholesteric phase, two solid solutions, and above 58 °C for compositions between 40 and 80 mol% HOBA a crystalline phase of mixed dimers. The MBOBA-DOBA system showed a crystalline phase of mixed dimers at all compositions, a cholesteric phase, and a twisted smectic C phase, which was dominated by mixed dimers at 60 and 70 mol% DOBA. We conclude that liquid-crystalline phases are generally dominated by mixed dimers, but in crystalline phases the formation of mixed dimers is promoted by a greater difference in molecular structure. The crystal structure of two of the pure compounds MBOBA and DOBA and comparable compounds have been determined for an evaluation of the arrangements of the molecules in the crystal and liquid-crystalline state.Key words: benzoic acid, crystal arrangement, phase diagrams, liquid crystal.

Physicochemical Characterization of PEG1500-12-acyloxy-stearate Micelles and Liquid Crystalline Phases

Langmuir ◽  
2005 ◽  
Vol 21 (18) ◽  
pp. 8146-8154 ◽  
Author(s):  
Cathy E. McNamee ◽  
Markus Nilsson ◽  
Christian von Corswant ◽  
Olle Söderman
Keyword(s):  
Liquid Crystalline ◽  
Physicochemical Characterization ◽  
Crystalline Phases ◽  
Liquid Crystalline Phases

Liquid Crystalline Nano-Segregated Structures in Hydrogen-Bonded Complexes of Fluoroalkyl Substituted Benzoic Acids

2001 ◽  
Vol 709 ◽  
Author(s):  
Etsushi Nishikawa ◽  
Jun Yamamoto ◽  
Hiroshi Yokoyama
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Cubic Phase ◽  
Benzoic Acid Derivatives ◽  
Smectic C ◽  
Texture Change ◽  
Double Gyroid ◽  
Substituted Benzoic Acids ◽  
Bonded Complexes ◽  
Hydrogen Bonded

ABSTRACTSeveral new benzoic acid derivatives having perfluorinated substituents were synthesized and their hydrogen-bonded complexes with 4, 4’-dipyridyl were prepared. In these acid/base complexes the incompatibility between perfluoroalkyl moieties and hydrocarbon parts is large, which can lead to organize nano-segregation structures. We have found in one of such complexes, that has a long flexible fluorinated moiety, a thermotropic cubic phase with Ia3d symmetry formed by double gyroid of two interpenetrating jointed rod networks with an estimated cell parameter of 10.9 nm. Furthermore another complex with a branched long perfluoroalkyl terminal chain exhibits a first order smectic A to smectic C phase transition, which is confirmed with thermal analysis detecting a large enthalpy change of 5.3 kJxmol-1, X-ray scattering experiments revealing a tilt angle jump, and polarized optical microscopy observing a remarkable texture change at the phase transition temperature.

Supramolecular ferroelectric liquid crystals. Hydrogen-bonded complexes between benzoic acids and chiral stilbazoles

1996 ◽  
Vol 21 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Hideyuki Kihara ◽  
Takashi Kato ◽  
Toshiyuki Uryu ◽  
Seiji Ujiie ◽  
Uday Kumar ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Benzoic Acids ◽  
Ferroelectric Liquid Crystals ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Mesophase Morphologies of Hydrogen-Bonded Complexes of Biphenyl-Substituted Diamino-1,3,5-triazines with Semiperfluorinated Benzoic Acids

2007 ◽  
Vol 19 (18) ◽  
pp. 4460-4466 ◽  
Author(s):  
Tachita Vlad-Bubulak ◽  
Jens Buchs ◽  
Alexandra Kohlmeier ◽  
Maria Bruma ◽  
Dietmar Janietz
Keyword(s):  
Benzoic Acids ◽  
Bonded Complexes ◽  
Hydrogen Bonded
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