A polar compound has a high chemical stability, high ability to align liquid crystal molecules and high solubility in a liquid crystal composition, and causes no decrease of liquid crystallinity of the liquid crystal composition, a liquid crystal composition contains the compound, and a liquid crystal display device includes the composition.
The compound is represented by formula (1), the composition contains the compound, and the liquid crystal display device uses the composition.
In formula (1), R1 is alkyl having 3 to 15 carbons, alkenyl having 4 to 15 carbons or the like; a is an integer from 2 to 12; and R2 is a group represented by formula (1a), formula (1b) or formula (1c).
In the formulas, S1 and S2 are independently a single bond, alkylene having 1 to 10 carbons; S3 is >CH— or >N—; S4 is >C< or >Si<; and X1 is —OH, —NH2 or the like.