Triplet Emission in Platinum-Containing Poly(alkynylsilanes)

Synthetic routes to novel oligomeric and polymeric platinum(II)-containing alkynylsilanes were developed. Soluble and thermally stable platinum(II) poly(alkynylsilanes) trans -[−Pt(PBu 3 ) 2 C⋮C( p -C 6 H 4 )C⋮CSiPh 2 C⋮C( p -C 6 H 4 )C⋮C−] n were prepared in good yield by CuI-catalyzed condensation polymerization of trans -[PtCl 2 (PBu 3 ) 2 ] with HC⋮C( p -C 6 H 4 )C⋮CSiPh 2 C⋮C( p -C 6 H 4 )C⋮CH. The regiochemical structure of the polymer was studied by NMR ( 1 H, 13 C, 29 Si, and 31 P) 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)(PEt 3 ) 2 C⋮C( p -C 6 H 4 )C⋮CSiPh 2 C⋮C( p -C 6 H 4 )C⋮CPt(Ph)(PEt 3 ) 2 ] and trans -[Pt(Ph)(PEt 3 ) 2 C⋮C( p -C 6 H 4 )C⋮CSiPh 2 C⋮C( p -C 6 H 4 )C⋮CPt(PBu 3 ) 2 C⋮C( p -C 6 H 4 )C⋮CSiPh 2 C⋮C( p -C 6 H 4 )C⋮CPt(Ph)(PEt 3 ) 2 ]. Our studies indicate that such organometallic poly(alkynylsilanes) show a strong triplet emission with a very high efficiency of intersystem crossing from the S 1 singlet excited state to the T 1 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 SiPh 2, C 6 H 4 and Pt(PR 3 ) 2 (R = Et, Bu) linkers. The photoconducting properties of such silicon-linked platinum polyyne are described.