Attaching Gold and Platinum to the Rim of Pyrene: A Synthetic and Spectroscopic Study

A series of pyrenyl complexes containing one or two AuPPh3 or Pt(PEt3)2Br groups have been synthesized to probe the effects of metal on the absorption and emission properties of the organic molecule. The absorption spectra of the complexes showed perturbation of the metal centers on the pyrenyl ring, as manifested by a red shift of the π → π* transitions of pyrene and intensification of the forbidden 1Lb band. The perturbation increased with the number of metal ions attached to the pyrenyl ring. The Pt ion was stronger than the Au ion in perturbing the electronic structure of the pyrenyl ring. All pyrenyl complexes displayed fluorescence and phosphorescence in degassed solutions. The heavy-atom effect of the metal ions enhanced the phosphorescence. The quantum yield of phosphorescence was sensitive to the positions of metalation.