A Closely-Coupled Pyrene Dimer Having Unusually Intense Fluorescence

A synthetic route is described for the preparation of 1,4-di(1-pyrenyl)butadiyne. The target compound, after purification by extensive column chromatography, has been characterized by NMR and exact-mass spectrometry. This material is highly-fluorescent in solution and, relative to pyrene, strongly absorbing in the near-UV region. Phosphorescence is observed at 77 K and formation of the metastable triplet state has been confirmed by laser flash photolysis. In marked contrast to pyrene, fluorescence from the target compound is not susceptible to self-quenching nor to the presence of dissolved oxygen. The average conformation of the molecule has been established by molecular modeling. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)