We show, that one molecule can communicate its logic output as input to another molecule. This transfer is achieved as an electronic energy transfer from a donor to an acceptor. We discuss a specific pair, the rhodamine 6G-azulene, for which there is considerable data, but the scheme is general enough to allow a wide choice of D and A pairs. We present results pertaining to a newly synthesized bichromophoric molecule based on this pair, in which a for the first time an all optical full adder is implemented, utilizing two-photon nonlinear optical excitation and intramolecular electronic energy transfer between the two moieties. (C) 2007 Elsevier B.V. All rights reserved.