A compound of the formula: ##STR32## wherein: X is O or S and Y is N (E)p R, where E is selected from the group consisting of CO and S02, p is an integer from 0-1, and R is selected from the group consisting of H, lower alkyls and halogenated lower alkyls; Z is a group linking X and Y and is a chain 2 carbon atoms in length, said chain being part of a fused benzene ring; and where one or mo