Configurational Isomers of a Stilbene-Linked Bis(porphyrin) Tweezer: Synthesis and Fullerene-Binding Studies

A new stilbene-tethered bis(porphyrin) tweezer 5 has been synthesized through a Sonogashira cross-coupling reaction. The tweezer exists as two configurational isomers [(Z) + (E)], which have distinct cavity sizes. Fullerene-binding studies show that the (Z) isomer of the tweezer has a significantly higher affinity toward both C-60 and C-70 compared to the (E) congener. In addition, the (Z) -> (E) photoisomerization of tweezer 5 is also discussed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)