Super‐Fluorinated Liquid Crystals: Towards the Limits of Polarity

Kirsch, Peer; Binder, Werner; Hahn, Alexander; Jährling, Kai; Lenges, Marc; Lietzau, Lars; Maillard, David; Meyer, V.; Poetsch, Eike; Ruhl, Andreas; Unger, Gerald; Fröhlich, Roland

doi:10.1002/ejoc.200800149

Cited by 46 publications

(26 citation statements)

References 39 publications

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“…6.7 kcal mol À1 für die s CHs* CF -Hyperkonjugation, während die s CC -s* CF -Hyperkonjugation nur etwa 3.5 kcal mol À1 zur elektronischen Stabilisierung des Gesamtsystems beiträgt. Kristallstrukturen von CF 2 O-verbrückten Flüssigkristallen [21] (z. B.…”

Section: Difluorether-verbrückte Flüssigkristalle Für Die Ips/ffs-tecunclassified

Der Fernseher in der Westentasche: Flüssigkristall‐ Materialentwicklung für das neue Jahrtausend

et al. 2013

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Neue Flüssigkristalle mit sehr niedriger Viskosität, gutem Mesophasenverhalten und hoher Zuverlässigkeit ermöglichen den Durchbruch vom flachen Computermonitor zum großformatigen LCD‐Fernseher. Fluor spielt hierbei eine entscheidende Rolle, nicht nur, weil es Polarität in organischen Molekülen induziert, sondern auch wegen seiner niedrigen Polarisierbarkeit und seiner schwach ausgeprägten Tendenz zur Ionensolvatation. Zusätzlich sind in fluorierten Flüssigkristallen subtile stereoelektronische Effekte am Werk und ermöglichen eine Feinabstimmung der gewünschten Eigenschaften. Dafür ist eine aufwendige Chemie erforderlich, wie sie sich normalerweise in der Spezialchemie allein schon aus Kostengründen verbietet. Der Markt für Fernseh‐Displays tritt heute in eine Phase der Sättigung ein. Bedingt durch die weite Verbreitung des Internets gibt es jedoch einen neuen Trend zu mobilen Geräten. Tablet‐PCs und Smartphones benötigen berührungsempfindliche Bildschirme und niedrigen Stromverbrauch. Neue LC‐Modi mit hocheffizienten Flüssigkristallen und zusätzlichen Komponenten, z. B. polymerisierbaren Materialien, werden in solchen Produkten verwendet.

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Section: Difluorether-verbrückte Flüssigkristalle Für Die Ips/ffs-tecunclassified

Der Fernseher in der Westentasche: Flüssigkristall‐ Materialentwicklung für das neue Jahrtausend

et al. 2013

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“…Fluorinated substituents, in fact, have been successfully incorporated into liquid crystalline molecules because of the excellent stability that is offered by the C-F bond as well as the small size and the low polarizability of the fluorine atom, which gives rise to very low intermolecular dispersion interactions 25 26 27 . Moreover the segregation occurring between PFC and HC chains allowed control over supramolecular liquid-crystalline phases, enhancing the smectic character of a mesomorphic material 28 29 30 .…”

Section: Introductionmentioning

confidence: 99%

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Cavallo

Bruce²,

Terraneo

et al. 2018

JoVE

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Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid crystals (ILCs). Taking advantages of the high specificity of XB for haloperfluorocarbons and the ability of anions to act as XB-acceptors, we obtained supramolecular complexes based on 1-alkyl-3-methylimidazolium iodides and iodoperfluorocarbons, overcoming the well-known immiscibility between hydrocarbons (HCs) and perfluorocarbons (PFCs). The high directionality of the XB combined with the fluorophobic effect, allowed us to obtain enantiotropic liquid crystals where a rigid, non-aromatic, XB supramolecular anion acts as mesogenic core.X-ray structure analysis of the complex between 1-ethyl-3-methylimidazolium iodide and iodoperfluorooctane showed the presence of a layered structure, which is a manifestation of the well-known tendency to segregation of perfluoroalkyl chains. This is consistent with the observation of smectic mesophases. Moreover, all the reported complexes melt below 100 °C, and most are mesomorphic even at room temperature, despite that the starting materials were non-mesomorphic in nature.The supramolecular strategy reported here provides new design principles for mesogen design allowing a totally new class of functional materials.

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“…For instance, the replacement of hydrogen by fluorine is commonly practised in medicinal [4–5] and agrochemical [6–7] research programmes. The dipole moment associated with the C–F bond has also rendered fluorine containing compounds important in the development of organic materials such as liquid crystals [8–9]. Strategic fluorination can add polarity to a molecule, however, such compounds do not generally increase in their hydrophilic capacity, thus selective fluorination leads to polar-hydrophobic properties [10].…”

Section: Introductionmentioning

confidence: 99%

Organofluorine chemistry: Difluoromethylene motifs spaced 1,3 to each other imparts facial polarity to a cyclohexane ring

Jones¹,

Callejo²,

Slawin³

et al. 2016

Beilstein J. Org. Chem.

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2,2-Dimethyl-5-phenyl-1,1,3,3-tetrafluororocyclohexane has been prepared and characterised as an example of a facially polarised cyclohexane containing 1,3 related CF2 groups. The dipolar nature of the ring arises from the axial orientation of two of the C–F bonds pointing in the same direction, and set by the chair conformation of the cyclohexane. This electrostatic profile is revealed experimentally both in the solid-state (X-ray) packing of the rings and by solution (NMR) in different solvents. A computationally derived electrostatic profile of this compound is consistent with a more electronegative and a more electropositive face of the cyclohexane ring. This placing of CF2 groups 1,3 to each other in a cyclohexane ring is introduced as a new design strategy which could be applicable to the preparation of polar hydrophobic cyclohexane motifs.

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Super‐Fluorinated Liquid Crystals: Towards the Limits of Polarity

Cited by 46 publications

References 39 publications

Der Fernseher in der Westentasche: Flüssigkristall‐ Materialentwicklung für das neue Jahrtausend

Der Fernseher in der Westentasche: Flüssigkristall‐ Materialentwicklung für das neue Jahrtausend

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Organofluorine chemistry: Difluoromethylene motifs spaced 1,3 to each other imparts facial polarity to a cyclohexane ring

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