1 Results Over the past few years significant research has been directed toward the development of organic materials for potential application in molecular photonic devices[1] and the development of sensors[2].Interest in these materials is primarily due to the infinite numbers of possible molecular structures with the desired properties,by virtue of the tremendous capabilities of organic synthesis.For the development of a new fluorescent molecular sensor consisting of a recognition moiety linked to a fluorescent moiety,the choice of the fluorophore is of major importance[3] in order to ensure better sensitivity.This presentation will focus on the design,the synthesis and the photophysical investigation on new fluorophores based on phosphane oxide[4] and phosphane sulfide[5] derivatives (See Fig.1). 1 Results Over the past few years significant research has been directed toward the development of organic materials for potential applications in molecular photonic devices [1] and the development of sensors [2] .Interest in these materials are primarily due to the infinite numbers of possible molecular structures with the desired properties, by virtue of the tremendous capabilities of organic synthesis. For the development of a new fluorescent molecular sensor consisting of a recognition moiety linked to a fluorescent moiety, the choice of the fluorophore is of major importance [3] in order to ensure better sensitivity. This presentation will focus on the design, the synthesis and the photophysical investigation on new fluorophores based on phosphane oxide [4] and phosphane sulfide [5] derivatives (See Fig.1).