New conjugated meso-tetrathienylporphyrin-cored derivatives as two-photon photosensitizers for singlet oxygen generation

A series of conjugated meso-porphyrin dendrimers containing conjugated fluorenyl dendrons, incorporating overall either four (3) or eight (4) fluorenyl units have been synthesized and characterized. These new molecular architectures are based on a central meso-tetra(thien-2-yl)porphyrin core (TThP). Their linear optical properties, absorption and photoluminescence, as well as selected nonlinear optical properties, were investigated and compared to those of the unsubstituted meso-(thien-2-yl)porphyrin core (5) and also to those of previously reported analogues featuring 1,4-phenylene groups (1 and 2) in place of 2,5-thienylene moieties. The positive role of these thienylene linkers over phenylene linkers on the two-photon absorption (2PA) cross-sections is clearly evidenced. A new family of conjugated meso-tetrathienylporphyrin-based dendrimers with fluorenyl arms has been synthesized. Their detailed luminescence properties and selected photophysical properties are discussed in the frame of two-photon-induced theranostics. [Display omitted] •Two new meso-tetra(thien-2-yl)porphyrins 3 and 4 have been obtained and characterized.•The two-photon absorption (2PA) cross-sections (σ2) of 3 and 4 were measured by TPEF, revealing strongly enhanced σ2.•Replacement of the 1,4-phenylene spacer at the periphery of the porphyrin core by a 2,5-thienylene one allows improvement of the 2PA cross-sections.•Porphyrins 3 and 4 are efficient Two-photon Photosensitizers for Singlet Oxygen Generation.