Expanded Rosarin: A Versatile Fullerene (C 60 ) Receptor

An expanded rosarian ( P 3 P 6 ) with a bowl-like conformation has been prepared and characterized in a one-pot procedure that involves condensing a bispyrrole pyridine precursor ( P 1 P 2 ) with benzaldehyde, followed by oxidation. Single crystal X-ray diffraction analysis reveals a bowl-like conformation in the solid state with an upper rim diameter defined by the meso -phenyl substituents of ca. 13.5 Å and a depth of roughly 6.3 Å. P 3 P 6 forms both 1:1 and 2:1 complexes with C 60 in the solid state. DFT reveals similar energies for the two binding modes. A 1:1 binding stoichiometry dominates in 1,2-dichlorobenzene- d 4 at the millimolar concentrations dictated by solubility consideration. The solution phase interactions between rosarian and C 60 were studied using 1 H NMR, UV–vis, and femtosecond transient absorption spectroscopies in 1,2-dichlorobenzene- d 4 or toluene. To our knowledge, this is the first report of an unfunctionalized porphyrinoid that forms a well-defined complex with C 60 in solution as well as in solid state.