Examples of aryl groups which are bonded to a carbon atom in a ring of a compound of this invention via the above-mentioned divalent linking groups and represented by R1 to R4 include aryloxy groups (for example, phenoxy groups or naphthoxy groups, etc.), aryloxycarbonyl groups (for example, phenoxycarbonyl groups or naphthoxycarbonyl groups, etc.), acyl groups (for example, benzoyl groups or naph