Extended‐Core Discotic Liquid Crystals Based on the Intramolecular H‐Bonding in <i>N</i>‐Acylated 2,2′‐Bipyridine‐3,3′‐diamine Moieties

Palmans, Anja R. A.; Vekemans, Jef A. J. M.; Fischer, Hartmut; Hikmet, R. A. M.; Meijer, E. W.

doi:10.1002/chem.19970030220

Cited by 140 publications

(150 citation statements)

References 19 publications

Supporting

Mentioning

141

Contrasting

Unclassified

Order By: Relevance

“…Structure 1 served just as a model for comparison with intramolecularly hydrogen-bonded structure 2, a precursor for extended core discotic liquid crystals of enhanced thermal stability. 5 The transparent, hexagon-shaped crystals of 1, obtained upon crystallization from methanol, suggested hexagonal symmetry and prompted us to investigate a single crystal by X-ray diffraction. As indicated in Fig.…”

Section: Take Down Policymentioning

confidence: 99%

Hydrogen-bonded porous solid derived from trimesic amide

Palmans

Vekemans

Kooijman³

et al. 1997

Chem. Commun.

Self Cite

View full text Add to dashboard Cite

Section: Take Down Policymentioning

confidence: 99%

Hydrogen-bonded porous solid derived from trimesic amide

Palmans

Vekemans

Kooijman³

et al. 1997

Chem. Commun.

Self Cite

View full text Add to dashboard Cite

“…Inspired by previous reports, 17,27 and the discotic columnar packing motif present in the structure of 2, the existence of additional high-temperature crystalline phases or thermotropic mesophases of 1 -5 was investigated (Table 2) using differential scanning calorimetry (DSC) and polarised optical microscopy (POM). Although the synthesis and characterisation of the methyl ester precursor to 1, 1-Me 3 has been previously reported, 6 no thermal studies have been previously carried out.…”

Section: Thermal Analysismentioning

confidence: 99%

Benzene-1,3,5-tricarboxamide n-alkyl ester and carboxylic acid derivatives: tuneable structural, morphological and thermal properties

et al. 2017

View full text Add to dashboard Cite

A family of five benzene-1,3,5-tricarboxamide (BTA) compounds with varied side arm functionality [alkyl: n =3, 4 and 5 chains; and ester and carboyxic acids) is reported. Investigations into their self-assembly behaviour revealed the extent to which minor changes in the side arm functionality can affect the structures formed. The carboxylic acid derivatives have a tendency to form gels, while the ester derivatives instead form crystalline phases with associated thermotropic phase transitions. The influence of the side chain length and terminal functional group is rationalised by a combination of single crystal X-ray diffraction studies and examinations of the bulk material properties.

show abstract

“…1). [3] As a result, a D ho phase exists in broad temperature ranges (250±350 K). However, the high viscosity and the high clearing temperatures of this mesophase might not be desirable for future applications.…”

mentioning

confidence: 99%

Lyotropic Liquid-Crystalline Behavior in Disc-Shaped Compounds Incorporating the 3,3′-Di(acylamino)-2,2′-bipyridine Unit

Palmans¹,

Vekemans

Hikmet

et al. 1998

Adv. Mater.

Self Cite

View full text Add to dashboard Cite

The rapidly increasing field of extended-core discotic liquid crystals has resulted in a number of compounds featuring mesophases in broad temperature ranges.[1] The introduction of secondary interactions in the construction of such large disc-shaped cores is expected to facilitate their synthesis.[2] Recently, we have reported on the synthesis of a new class of extended-core, C 3 -symmetrical liquid crystals such as 1, based on the 3,3¢-di(acylamino)-2,2¢-bipyridine unit. Intramolecular hydrogen bonding preorganizes the interior of the molecules in conformations close to planarity ( Fig. 1). [3] As a result, a D ho phase exists in broad temperature ranges (250±350 K). However, the high viscosity and the high clearing temperatures of this mesophase might not be desirable for future applications. Therefore, controlling these features by the addition of a suitable solvent might be highly attractive. The existence of both thermotropic and lyotropic mesomorphism in disc-shaped compounds is rather unusual as columnar mesophases normally show insufficient stability to support the latter. Enhanced p-stacking interactions arising from extended cores, strong phase separation of the core from the solvent, [4] intermolecular hydrogen bonding, [5] or metal±ligand interactions [6] can, however, overcome the stability problem and encourage the formation of stable columnar phases. Here, we report on the lyotropic mesomorphism observed when compound 1 is dissolved in alkane solvents. The nature of the mesophase present has been investigated using polarization microscopy and X-ray diffraction. Furthermore, the effect of the solvent on the clearing temperature has been evaluated. Finally, the feasibility of orienting the columnar mesophase in large monodomains using an electric field is discussed.Compound 1 gives rise to viscous solutions when dissolved in alkane solvents such as hexane, cyclohexane, and dodecane starting from concentrations of approximately 1 mg/mL. In dodecane, the solutions become birefringent starting from approximately 5 wt.-%. Solutions of compound 1 in dodecane have been studied in concentrations ranging from 5 to 55 wt.-%. Figure 2 summarizes the clearing temperatures of the birefringent solutions as a function of their composition. The temperature range over which the mesophase is displayed is rather broad: a 25 wt.-% solution of compound 1 shows a transition into the isotropic state at a temperature as high as 138 C. This stability may find its origin in the strong p-stacking interactions between the discs owing to the size of the aromatic core and to a strong phase separation of the aromatic core with respect to the solvent applied. [7] The relationship between the amount of 1 in dodecaneÐexpressed in wt.-%Ðand the clearing temperature T cl seems to be linear. Hence, the

show abstract

Extended‐Core Discotic Liquid Crystals Based on the Intramolecular H‐Bonding in N‐Acylated 2,2′‐Bipyridine‐3,3′‐diamine Moieties

Cited by 140 publications

References 19 publications

Hydrogen-bonded porous solid derived from trimesic amide

Hydrogen-bonded porous solid derived from trimesic amide

Benzene-1,3,5-tricarboxamide n-alkyl ester and carboxylic acid derivatives: tuneable structural, morphological and thermal properties

Lyotropic Liquid-Crystalline Behavior in Disc-Shaped Compounds Incorporating the 3,3′-Di(acylamino)-2,2′-bipyridine Unit

Contact Info

Product

Resources

About