New luminescent fluorenyl-armed linear porphyrin trimers with diphenylacetylene bridges

• Synthesis of new porphyrin trimers within totally eight peripheral fluorenyl arms is presented.
• New bis zinc trimer exhibits a relatively high luminescence quantum yield (9%), higher than reference compound ZnTPP (3.3%) and parent compound ZnTFP (5%).
• We report an efficient energy transfer from the fluorenyl arms toward the porphyrins, as well as from the zinc complexes toward the free base central porphyrin.

First a series of porphyrins bearing various fluorenyl donor groups is presented; an intermediate porphyrin bearing three fluorenyl arms (zinc complex 12) and compound 13, bearing only two fluorenyl groups. Then starting from these building blocks, synthesis of new porphyrin trimers 7 and 8, with in totally eight peripheral fluorenyl arms is performed by using a palladium catalyst. Photophysical properties; absorption and luminescence, of new trimers 7 and 8 are presented. We can then compare these properties to those of reference porphyrin monomer TFP (2), as well as to those of porphyrin dendrimers bearing various numbers of fluorenyl arms (3 and 4) and finally to those of the corresponding dimers 5 and 6, which are the precursor models of this work.

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