Triplet Emission in Platinum-Containing Poly(alkynylsilanes)

Abstract

Synthetic routes to novel oligomeric and polymeric platinum(II)-containing alkynylsilanes were developed. Soluble and thermally stable platinum(II) poly(alkynylsilanes) trans-[−Pt(PBu3)2C⋮C(p-C6H4)C⋮CSiPh2C⋮C(p-C6H4)C⋮C−]n were prepared in good yield by CuI-catalyzed condensation polymerization of trans-[PtCl2(PBu3)2] with HC⋮C(p-C6H4)C⋮CSiPh2C⋮C(p-C6H4)C⋮CH. The regiochemical structure of the polymer was studied by NMR (1H, 13C, 29Si, and 31P) spectroscopy. We report the optical absorption and photoluminescence spectra of such metal-based organosilicon polymer and compare the data with their oligomeric model complexes trans-[Pt(Ph)(PEt3)2C⋮C(p-C6H4)C⋮CSiPh2C⋮C(p-C6H4)C⋮CPt(Ph)(PEt3)2] and trans-[Pt(Ph)(PEt3)2C⋮C(p-C6H4)C⋮CSiPh2C⋮C(p-C6H4)C⋮CPt(PBu3)2C⋮C(p-C6H4)C⋮CSiPh2C⋮C(p-C6H4)C⋮CPt(Ph)(PEt3)2]. Our studies indicate that such organometallic poly(alkynylsilanes) show a strong triplet emission with a very high efficiency of intersystem crossing from the S1 singlet excited state to the T1 triplet excited state. The dependence of intersystem crossing and the spatial extent of singlet and triplet excitons as a function of the central spacer group is discussed in polymetallaynes possessing SiPh2, C6H4 and Pt(PR3)2 (R = Et, Bu) linkers. The photoconducting properties of such silicon-linked platinum polyyne are described.