The present invention relates to heteroaromatic isothiocyanates of formula N

##STR00001##

as defined in claim 1, to liquid-crystalline media comprising one or more compounds of formula N and to high-frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g. phased array antennas.

A liquid crystal composition as a material used for elements for controlling electromagnetic wave signals in a frequency range of 1 GHz to 10 THz, and an element containing this composition are provided. In the liquid crystal composition, a characteristic balance is excellent, and at least one of characteristics of a wide temperature range of a nematic phase, a large refractive index anisotropy in a frequency region used for control, and a small dielectric loss tangent (tan ?) is satisfied.

A liquid crystal composition containing at least one compound selected from compounds represented by Formula (1) is provided.

##STR00001##

For example, R.sup.1 is an alkyl having 1 to 12 carbon atoms; ring A.sup.1 is 1,4-phenylene; L.sup.11, L.sup.13, L.sup.14, L.sup.16, Y.sup.11, and Y.sup.12 are each hydrogen; L.sup.12 is fluorine; and L.sup.15 is methyl.

Provided are a liquid crystal compound satisfying at least one of physical properties such as high stability to heat or light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, large optical anisotropy, large negative dielectric anisotropy, a suitable elastic constant and good compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound is represented by formula (1):

##STR00001##

wherein, R.sup.1 and R.sup.2 are alkyl having 1 to 15 carbons; A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are 1,4-cyclohexylene and 1,4-phenylene; Z.sup.1, Z.sup.2, Z.sup.3 and Z.sup.4 are a single bond; Y.sup.1, Y.sup.2 and Y.sup.3 are fluorine; and a, b, c and d are 0 or 1, and a sum of a, b, c and d is an integer from 0 to 3, or the like.

A liquid crystal composition as a material used for elements for controlling electromagnetic wave signals in a frequency range of 1 GHz to 10 THz, and an element containing this composition are provided. In the liquid crystal composition, a characteristic balance is excellent, and at least one of characteristics of a wide temperature range of a nematic phase, a large refractive index anisotropy in a frequency region used for control, and a small dielectric loss tangent (tan ) is satisfied. A liquid crystal composition containing at least one compound selected from compounds represented by Formula (1) is provided: ##STR00001##
wherein R.sup.1 is an alkyl having 1 to 12 carbon atoms; ring A.sup.1 is 1,4-phenylene; L.sup.11, L.sup.13, L.sup.14, L.sup.16, Y.sup.11, and Y.sup.12 are each hydrogen; L.sup.12 is fluorine; and L.sup.15 is methyl.

Heteroaromatic isothiocyanates of formula N ##STR00001##
wherein R.sup.N, A.sup.N1, A.sup.N2, Z.sup.N1, Z.sup.N2, W, X.sup.1, X.sup.2, and n are as defined herein can be used in liquid crystalline media. Liquid-crystalline media comprising one or more compounds of formula N are suitable for use in high-frequency components, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g., phased array antennas.