Pyridyl-Endcapped Polyynes: Stabilized Wire-like Molecules.

A 4-ethynylpyridyl derivative with sterically shielding phenyl groups in the 3- and 5-positions has been synthesized and used to terminate a series of polyynes. This approach allows for the synthesis of stable polyynes up to an octayne, twice as long as previous accessible for "unstabilized" pyridyl-endcapped polyynes. The potential of these polyynes as wire-like linkers to metal centers is demonstrated by axial coordination of pyridyl groups to zinc- and ruthenium-metalloporphyrins.