The structure of poly(di-n-hexyl germane) has been investigated using X-ray and conformational energy analysis. Wide-angle X-ray diffraction analysis shows that the polymer undergoes an order/disorder transition at about 15°C. The polymer is known to exhibit thermochromism associated with this phase transition. Below the transition temperature, the backbone conformation is all-trans and the molecules are arranged in an orthorhombic unit cell. Above the transition temperature, the backbone disorders and the polymer loses long-range ordering. Fixed bonding conformational energy calculations found the lowest energy structure to be a 7/3 helix, very similar to that found for poly(di-n-hexyl silane). Most probably, the observed all-tram backbone conformation is due to intermolecular interactions which force the germanium backbone to an all-trans conformation. In order to carry out the molecular mechanics calculations, non-bonded energy parameters for germanium atoms were derived.
Посилання на статтю:
The low-temperature structure of poly (di-n-hexyl germane) / S. S. Patnaik, A. J. Greso and B. L. Farmer* // Polymer. – 1992. – Vol 33. – P. 5115-5120.