wherein R1, R2, R3 and R4 are each a substituent, which may be selected from the group consisting of hydrogen, an alkyl group with for example from 1 to about 25 carbon atoms and more specifically from 1 to about 6 carbon atoms, an aryl group with about 6 to about 30 carbon atoms, an alkoxy group with from 1 to about 25 carbon atoms and more specifically from 1 to about 6 carbon atoms, a halogen,