"Such substituent groups are limited only by the ability of one of ordinary skill in the art to prepare stable compounds which have the protein error indicator properties of the present invention, and include such groups as unsubstituted and substituted alkyl, unsubstituted and substituted aryl, alkoxy, aryloxy, halo (e.g., fluoro, chloro, bromo), nitro and substituted amino such as dialkylamino." . . . .