Synthesis, structure, and one- and two-photon absorption properties of N-substituted 3,5-bisarylidenepropenpiperidin-4-ones

A series of 3,5-bisarylidenepropenpiperidin-4-one compounds with a D–π–A–π–D structure, containing donors (R1 = NEt2, NMe2) and terminal groups at the central nitrogen ring atom (R2 = H, Me, Et, P(O)(OEt)2) was synthesized with the goal of improving one- and two-photon absorption properties of the earlier designed compounds, which potential activity as photosensitizers was demonstrated with appeal of biological and spectroscopic data. Several of the compounds studied have a two photon absorption cross section approximately six times larger than previously measured for 3,5-bisarylidenemethylenpiperidin-4-ones with short alkene chains. Spectral data are discussed in connection with structural characteristics of studied materials.