A simple derivative of a well-known dye bodipy appears to be a satisfactory sensitizer for singlet oxygen. Moreover, the rate of singlet oxygen generation can be modulated by two cancer-related cellular parameters, sodium ion concentration and acidity. Singlet oxygen generation rate is maximal when sodium ions and an organic acid were added. The operation of this molecular automaton follows AND logic, which introduces an additional layer of selectivity in the photodynamic action of the reagent. It should also be noted that in this system sensing, computing and actuating functions are realized within a single molecule. Copyright © 2008 American Chemical Society.