New meso-tetrafluorenylethynyl porphyrin platform

To improve conjugation between a central porphyrin core and its peripheral fluorenyl antennae, we have introduced in the meso-tetrafluorenyl porphyrin (TFP-Bu) unit an ethynyl spacer at the meso positions. By this means, we have synthesized and characterized a new meso-alkynyl fluorenyl porphyrin (TAFlP). We discuss the effect of this extra extension of the π manifold on the optical properties. This enlarged porphyrin core, TAFlP, is foreseen as a key building block for the design of new dendrimers for theranostic applications. The constant improvement of porphyrin-based dendrimers featuring conjugated fluorenyl dendrons is recalled herein and demonstrates the important role of the central core structure in determining linear and nonlinear optical properties. Further improvement of these properties seems possible with TAFlP-like structures based on observations made for dendrimers recently obtained. This makes the exploration of such new molecular architectures appealing for photodynamic therapy (PDT) and related applications.