aromatic group, ???(Y???O)??? is represented by the formula (3) in which R9 and R10 may be the same or different and are a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group and R11 and R12 may be the same or different and are a hydrogen atom, a halogen atom, an alkyl group having 6 or less carbon atoms or a phenyl group, ???(Y???O)??? is an arrangement of one kind of st