摘要：

wherein R is an alkyl or alkenyl group which is optionally interposed with one or more oxygen or sulphur atoms, Y is independently selected from oxygen or sulphur, n is an integer of from 2 to 8, X is a direct bond, C 1-4 alkylene or C 2-4 alkenylene, and A is selected from a various specified ring structures. The liquid crystal material (compounds) are of low birefringence and are U.V. stable and are useful in liquid crystal devices that need low birefringence such as reflective displays, or which are exposed to high levels of U.V. light such as phosphor display cells.

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