Structure of a Transition Metal-Containing Polyyne

Electron diffraction and low-dose, high-resolution imaging techniques have been used to obtain structural information for a rigid-rod polyyne containing platinum atoms directly bonded into the main chain. The high-resolution images show details of the arrangement of the molecular chains into crystallites ~50 nm in diameter; dislocations and grain boundaries have also been imaged. A combination of electron diffraction and information derived from image processing of the high-resolution images indicates a unit cell in which parameters of a = 2.08 nm, c = 1.20 nm, and 90° < β < 93° have been measured and where b has tentatively been assigned as ~ 1.9 nm. The variations in β relate to improvements in the degree of orientation of the polymer chains that arise from slight stretching of the thin films.