Synthesis of Monodisperse Platinum Acetylide Oligomers End-Capped with Naphthalene Diimide Units

Abstract

We report the synthesis and structural characterization of a series of monodisperse platinum acetylide oligomers with the general structure NDI-[Ph−C≡C−Pt(PBu 3 ) 2 −C≡C−] n −Ph−NDI, where n = 2, 3, 6, or 10, Ph = 1,4-phenylene, NDI is a substituted 1,4,5,8-naphthalene diimide, and the geometry at the Pt centers is trans . The oligomers were synthesized via an iterative-convergent approach utilizing organometallic synthons that feature orthogonally protected terminal acetylene units. The 31 P NMR spectra of the oligomers are especially revealing as to their structure, due to a difference in chemical shift for the internal and terminal Pt(PBu 3 ) 2 units. The oligomers were also characterized by electrochemistry, UV−visible absorption, and photoluminescence spectroscopy. The emission spectroscopy reveals that the triplet exciton is efficiently quenched in the NDI end-capped oligomers, and the quenching is thought to arise due to photoinduced charge separation.