Collect. Czech. Chem. Commun. 1985, 50, 1553-1564

Stability of molecular aggregates of hydrocarbons with all-trans chains and translation of the molecules

Ján Gajdoša and Tomáš Blehab

a Institute of Chemistry
b Polymer Institute, Centre of Chemical Research, Slovak Academy of Sciences, 842 38 Bratislava


Potential energy has been calculated for molecular aggregates formed of all-trans extended hexanes with various arrangements of the central molecule surrounded by the first coordination sphere. Differences in stabilities of the aggregates are connected with biaxial character of asymmetry of the interaction energy of extended paraffins. When investigating the multiparameter interaction potential of the partially ordered systems of hydrocarbon chains, the first step consisted in determination of the energy barriers to longitudinal shifts of the central molecules at various distances of the surrounding molecules. Destabilization of the aggregates with displaced molecules is due to both the mismatch of the central molecule to the matrix and effective shortening of that part of the central molecule which is "immersed" in the aggregate. The energetics of the model aggregates is made use of in elucidating the role of translation of paraffins and cognate molecules in rotational phase, in mesophases, and at a forced shortening of the chains connected with conformational transition.