Improved methods for selective detection of highly toxic organophosphorus compounds are needed. In an effort to develop sensors that distinguish between various organophosphorus compounds based on their toxicity, we have developed a series of dual electrochemical and optical sensors based on dipyrido-[3,2-a:2'3'-c]phenazine (DPPZ). The synthesis of a series of DPPZ ligands were synthesized, characterized, and their interaction with various organophosphorous compounds was studied. In acetonitrile, DM-BDPPZ fluoresces green. Addition of the nerve gas analogue diethylchlorophosphate (DCP) resulted in fluorescence color change from green to orange accompanied by an increase in fluorescence intensity and lifetime, accompanied by shifts in electrochemical signals. However, addition of the nerve gas analogue dimethyl methylphosphonate (DMMP) resulted in a slight increase in fluorescence intensity and lifetime, but no color change or electrochemical changes. Fluorescence intensity of DM-BDPPZ upon addition of fenthion, an organophosphorus pesticide, resulted in fluorescence quenching and the lifetime decreased, accompanied by dramatic electrochemical shifts. The ability of DPPZ derivatives to distinguish between various organophosphorus compounds, is a unique feature and a significant requirement for building novel organophosphorus sensors.