Synthesis and Characterization of New Ferrocene, Porphyrin and C60 Triads, Connected by Triple Bonds

Electron and energy transfer are important topics in the chemistry of biological and artificial systems and have been extensively studied over the past twenty years.1 Photosynthesis in plants and bacteria is based on chemical reactions induced by the electron-transfer phenomena between natural tetrapyrrolic pigments, such as chlorophyls and related molecules, and quinones, both embedded in a protein matrix.2 The entire process is not yet well3understood and more information can be obtained by the use of synthetic models. During our studies on the possibility to use molecular wires to connect to the beta-pyrrole positions of the porphyrins one C60 unit through the assembling of one or more triple bond, we found that it was very convenient and important to have a large delocalization of the π electrons between the donor and the acceptor moieties of the models.4 Recently we have reported the beta functionalization of H2TPP by one or two ferrocene molecules in the 2 and 3 positions through ethynyl or phenylethynyl groups, applying a new approach of the Sonogashira reaction, never used before in the case of porphyrins.5 In this communication we report on the synthesis of new triads, useful as a model for investigating the electron-transfer processes, connecting ferrocene and C60 to the 2,12 pyrrole positions of H2TPP through ethynyl bonds. In Figures 1 the structure of triad 1 free base and its zinc complex is reported. We will also show the fluorescence spectra of the triads compared to the related reference compounds