Interactions of “organic fluorine” have gained great interest not only in the context of crystal engineering, but also in the systematic design of functional materials. The first part of this tutorial review presents an overview on interactions known by organic fluorine. This involves π–πF, C–F⋯H, F⋯F, C–F⋯πF, C–F⋯π, C–F⋯M+, C–F⋯CO and anion–πF interactions, as well as other halogen bonds. The effect of the exchange of H vs. F is discussed by means of several examples and a short introduction to the young field of “fluorous” chemistry is given. The second part is dedicated to numerous applications of fluorine and fluorous interactions. It is shown how application of fluorination is used to enable a number of reactions, to improve materials properties and even open up new fields of research.

Organic fluorine compounds: a great opportunity for enhanced materials properties.

The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy (Δe), which contains at least one compound selected from the group of compounds of the formula I, II A and II B and at least one compound of the formula I* in which R0, R1, R2, R1*, X1, X2, A1, A1*, A2*, Z1, Z1*, Z2*, L1*, L2*, p, q, v, m and m* are as defined in Claim 1, and to the use thereof for an active-matrix display based on the ECB, VA, PS-VA, FFS, PALC or IPS effect.

Liquid Crystalline Medium

This critical review begins with a brief, but essential, introduction to the special nature of liquid crystal materials, their peculiar properties, and their commercial applications, followed by an introductory insight into the remarkable nature of the fluoro substituent, and its fascinating influence on the properties of organic compounds. However, the main focus of the review is to discuss the enormous amount of exciting research on fluorinated liquid crystals that has been reported. The small size of the fluoro substituent enables its incorporation into all types of liquid crystal, including calamitic, discotic, banana, lyotropic, and polymers, without ruining the liquid crystalline nature of the material. However the fluoro substituent is larger than hydrogen, and hence causes a significant steric effect, which combined with the high polarity, confers many fascinating, and often remarkable, modifications to melting point, mesophase morphology and transition temperatures, and the many other very important physical properties, such as dielectric anisotropy, optical anisotropy, and visco-elastic properties. There are many different positions within a liquid crystal structure where a fluoro substituent can be located, including (i) a terminal position, (ii) within a terminal chain, as a semi-fluorinated or as a perfluorinated chain, or as one fluoro substituent at a chiral centre, (iii) as part of a linking group, and (iv) a lateral position in the core section. Such variety enables the interesting and advantageous tailoring of properties, both for the fundamental purposes of establishing structure–property relationships, and for materials targeted towards commercially-successful liquid crystal display applications.

Fluorinated liquid crystals – properties and applications

The invention is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a large optical anisotropy, a large positive dielectric anisotropy, a large specific resistance, a large elastic coefficient, a high stability to ultraviolet light and heat, or that is suitably balanced between at least two of the characteristics. As the liquid crystal display device containing the compositions is to provide an AM device that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth, thus it can be used for the liquid crystal projector, liquid crystal television and so forth.

Liquid crystal composition and liquid crystal display device

Disclosed are: a liquid crystal composition, which satisfies at least one property selected from a high upper-limit temperature in a nematic phase, a low lower-limit temperature in a nematic phase, a low viscosity, high optical anisotropy, high dielectric anisotropy, a high specific resistivity, high stability to ultraviolet ray, high stability to heat and the like, or which has an adequate balance between at least two properties selected from the above-mentioned properties; and an AM element having a short response time, a high voltage holding ratio, a high contrast ratio, a long service life and the like. Specifically disclosed are: a liquid crystal composition which comprises a specific pentacyclic compound having high optical anisotropy and high dielectric anisotropy as the first component, a specific compound having a low viscosity as the second component, and a specific tetracyclic compound having a high upper-limit temperature as the third component, and which has a nematic phase; and a liquid crystal display element comprising the composition.

Liquid crystal composition and liquid crystal display element

Super‐Fluorinated Liquid Crystals: Towards the Limits of Polarity

Optionally-substituted 2-fluoro-4'-phenoxydifluoromethyl-biphenyl compoundes are new. Compounds of formula (I) are new. R 1> : H, F, Cl, Br, optionally halogenated 1-15C alkyl (optionally with in-chain -Ctriple boundC-, -CH=CH-, -COO-, -OCO-, -CO- or -O-); A 1> : trans-1,4-cyclohexylene or cyclohexenylene (both optionally substituted with F and/or having non-adjacent CH 2 group(s) replaced by O and/or S), or 1,4-phenylene (optionally with 1 or 2 CH groups replaced by N and/or with one or more H replaced by Br, Cl, F, CN, methyl, methoxy, fluorinated methyl or fluorinated methoxy); Z 1> : single bond, -CH 2O-, -COO-, -CF 2O-, -CH 2CH 2CF 2O-, -CF 2CF 2-, -CH 2CF 2-, -CH 2CH 2-, -(CH 2) 4-, -CH=CH-, -CH=CF-, -CF=CF- or -Ctriple boundC-; L 1>, L 2> : H or F; X 1> : F, Cl, CN, NCS, SF 5, or 1-7C halogenated alkyl, alkoxy, alkenyl or alkenyloxy; a : 0, 1 or 2. Independent claims are also included for (1) a method (M1) for the production of (I) by reacting boronic acids or esters of formula (IIA) or (IIB) with compounds of formula (III) in presence of transition metal catalysts (2) a method (M2) for the production of (I) by reacting compounds of formula (IV) with boronic acids or esters of formula (V) in presence of transition metal catalysts (3) liquid crystalline (LC) media with at least two mesogenic components, containing at least one compound (I) (4) electro-optical LC displays containing such media. R 3>, R 4> : 1-12C alkyl, or R 3>+R 4> = alkylene or phenylene (all optionally substituted); Hal : -O(SO 2)CF 3, Cl, Br or I. [Image] [Image] [Image] [Image].

Fluorophenyl compounds for liquid-crystalline mixtures

New materials based on the 1,1,6,7-tetrafluoroindane skeleton were synthesized via ortho-metallation and intramolecular Heck cyclization followed by an oxidative fluorination procedure. The materials offer improved properties over liquid crystals currently employed in flat panel LCD-TVs.

1,1,6,7-Tetrafluoroindanes: improved liquid crystals for LCD-TV application

Disclosed are dibenzofuran and dibenzothiophene derivatives of the general formula I, in which X 1 , X 2 , W, Y, R, A, Z and m have the meaning defined in claim 1, to a process for the preparation thereof, to the use thereof as components in liquid-crystalline media, and to electro-optical display elements which contain the liquid-crystalline media according to the invention.

Fluorinated dibenzofuran and dibenzothiophene derivatives

The invention relates to a liquid-crystalline medium, preferably having a nematic phase and dielectric anisotropy of 0.5 or more, which has particular dielectric properties, in that it has 
- either a dielectric constant perpendicular to the director (e ⊥ ) in the range of 2 or more to less 8 or less and at the same time a ratio of the dielectric constant perpendicular to the director (e ⊥ ) to the dielectric anisotropy (Δe), i.e. (e ⊥ / Δe) of 1.0 or more or 
- or a dielectric constant perpendicular to the director (e ⊥ ) of 8 or more and a dielectric anisotropy (Δe) of 26 or less and 
preferably comprises one or more compounds having a high dielectric constant perpendicular to the director (e ⊥ ) and a high average dielectric constant (eav.), 
to the use thereof in an electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect, to displays of this type which contain a liquid-crystalline medium of this type, and to the use of the compounds of formula I for improvement of the transmission and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

Lars Lietzau

Papers

Super‐Fluorinated Liquid Crystals: Towards the Limits of Polarity

Fluorophenyl compounds for liquid-crystalline mixtures

1,1,6,7-Tetrafluoroindanes: improved liquid crystals for LCD-TV application

Fluorinated dibenzofuran and dibenzothiophene derivatives

Liquid-crystalline medium and liquid-crystal display comprising the same