Influence of the spacer in bis-porphyrinic tweezers on the association constant for host/guest complexes

Abstract

Detailed complexation studies of two rigid tweezers bearing mono- or tris-anthracenic spacers is reported, along with the synthesis and characterization of two new tweezers bearing flexible nucleosidic linkers. For flexible tweezers bearing the two porphyrins at O -5' and O -3' positions of the ribose, the association constant for the complexation of DABCO increases, when compared to the association constant for the same base with a reference mono-porphyrin. The nucleoside seems to confer sufficient preorganization to this dimer to enhance the binding constant, documenting the fact that rigid dimers are not necessary for preorganization, and opening new routes to the rapid synthesis of flexible tweezers capable of complexing guests with high association constants.