Synthesis and optical spectroscopy of linear long-chain di-terminal alkynes and their Pt–σ-acetylide polymeric complexes

Abstract

A variety of straight-chain alkynes with extended π-conjugation through benzene, anthracene and thiophene linker units in the backbone, H—CC—R′—CC—R—CC—R′—CC—H (R =p-C₆H₄, 9,10-C₁₄H₈, 2,5-C₄H₂S; R′=p-C₆H₄, p-C₆H₄-C₆H₄-p) has been synthesized. The alkynyl chromophores with an anthracene spacer unit are highly emissive in solution with luminescence quantum yields of up to 0.5. The platinum σ-acetylide polymeric complexes of the above ligands show strong absorptions associated with metal-to-alkynyl ligand charge transfer (MLCT) transitions. It is clear that the π-conjugation is maintained through the metal centres and the optical gap for the polymer, [graphic omitted]Pt(PBuⁿ₃)₂-CC-p-C₆H₄-CC-9,10-C₁₄H₈-CC-p-C₆H₄-CC[graphic omitted]_n is lower than for the complexes [graphic omitted]Pt(PBⁿ₃)₂-CC-R′-CC-R-CC-R′-CC[graphic omitted]_n(R =p-C₆H₄, 2,5-C₄H₂S; R′=p-C₆H₄; p-C₆H₄-C₆H₄-p).