Complexation of Unsaturated Carbon−Carbon Bonds in π-Conjugated Polymers with Transition Metals

The present paper explores the possibility of preparing π-conjugated organometallic polymer hybrid systems based on a poly(p-phenylene ethynylene) (PPE) derivative, in which the ethynylene moieties of the polymer are coordinated to platinum(II) centers. The use of the “bifunctional” [Pt−(μ-Cl)Cl(PhCHCH2)]2 (2) allows, under appropriate conditions, the formation of three-dimensionally cross-linked, conjugated PPE−platinum(II) networks. The synthesis of [Pt−(μ-Cl)Cl(PhC⋮CPh)]2, as a model compound, and a series of model reactions of 2 with diphenylacetylene (3) have enabled an NMR study which has revealed a number of equilibria, and suggests a mixed Pt−styrene−acetylene complex as a key structure. As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift upon complexation with 2.