Abstract: A compound of formula (I) or a dimer thereof; where R1 and R2 are independently selected from optionally substituted alkyl, optionally substitituted alkenyl, optionally substituted alkynyl, a functional group or a group of sub-formula (i) —(O)m—(CH2)p—R7??(i) where m is 0 or 1; p is an integer of from 1 to 12; R7 is a group of formula —CqX2q+1 where q is an integer of from 1 to 12 and X is halogen such as fluoro, or R7 a group of sub-formula (ii) where k is an integer of from 1 to 10, R8, R10, and R12 and each R9 and R11 are independently selected from alkyl, alkenyl or aryl, such as lower alkyl and in particular methyl; provided that at least one of R1 or R2 is a group of sub-formula (i); R3, R4, R5 and R6 are independently selected from hydrogen or halogen, and in particular fluorine, n is 0 or 1, and A is a ring structure as specified. Compounds of formula (I) may have liquid crystal properties and/or be useful in liquid crystal devices.