Safranines have the ability to catalyze electron transfer reactions similar to those catalyzed by flavins without the oxygen activation side reactions that flavins are also structured to perform. We are constructing a series of de novo-designed helical bundle enzymes in which safranines act as the cofactors which catalyze the NADH-dependent reduction of nitroaromatics. A novel chemical synthesis has been developed which allows the rapid generation of many safranine derivatives, each of which has differing reduction potentials, visible and fluorescent spectra. Selection of the appropriate derivative will allow the tuning of the catalytic activity towards particular nitroaromatic substrates. These novel proteins are intended for use in explosives sensing, chemotherapeutic prodrug activation and �green' chemical catalysis.