Synthesis, redox and optical properties of low-bandgap platinum(II) polyynes with 9-dicyanomethylene-substituted fluorene acceptors

In view of the strong electron-withdrawing nature of the cyano substituent, a blue donor/acceptor-type organometallic polymer (trans[Pt(PBu3)(2)-C=C-R -C=C-](n) (R = 9-dicyanomethylenefluorene-2,7-diyl)) was prepared in good y ield by CuI-catalyzed polymerization involving the dehydrohalogenating coup ling of trans-[Pt(PBu3)(2)Cl-2] and H-C=C-R-C=C-H. The thermal, redox and p hotoconducting properties of the polymer are reported. Electronic absorptio n studies indicate that it has a bandgap of L58 eV which is the lowest amon g any of the metal poly-yne polymers reported in the literature. The deriva tization of the polymer backbone with electron deficient dicyano-substitute d electron acceptor in the side chain is found to be effective to tune the bandgap of this class of materials while maintaining their solubility and p rocessability.