Synthesis, characterisation and electronic properties of a series of platinum(II) poly-ynes containing novel thienyl-pyridine linker groups

The synthesis and characterisation of a series of novel poly-yne polymers, trans-[-(PⁿBu₃)₂Pt(C≡C-L-C≡C)-] _n (L = 2-(2′-thienyl)-pyridine (L1), 2,5-bis(2′-thienyl)pyridine (L2), 6,6′-bis(2″-thienyl)-3,3′-bipyridine (L3)), and the corresponding platinum dimers trans-[(PEt₃)₂(Ph)Pt(C≡CLC≡C)Pt(Ph)(PEt ₃)₂] are described. The dimers were prepared by the reaction of two equivalents of trans-[Pt(PEt₃)₂(Ph)Cl] with one equivalent of the diterminal diyne HC≡C-L-C≡CH, in CuI catalysed dehydrohalogenation reactions in CH₂Cl₂-Prⁱ₂NH, while the polymers are obtained similarly from the diyne and one equivalent of trans-[Pt(PⁿBu₃)₂Cl₂]. The optical absorption and photoluminescence spectra of the polymers with L1 and L2 linker groups are reported. The optical gaps are 465 nm (2.67 eV) and 486 nm (2.55 eV), respectively. The photoluminescence spectrum for each polymer exhibits one band at room temperature. At 10 K, low-energy emission bands emerge which are attributed to emission from the triplet excited state. The results of these studies are compared with those obtained for other platinum-containing poly-yne and related organometallic polymers.