Molecular modelling of self-assembled alkynyl monolayer structures-Unnatural symmetry units,surface bonding,and topochemical polymerization.

摘要

Geometrc modelling techniques are used to map the potential energies of packing for self-=assembled alkyl-and phenyl-backboned monolayers across a range of intermolecular separations.Natural packing distances of 4.2-4.4A produce less stable,more isotropic monolayers because of repulsive interchain contacts.Optimizations at unnatural surface densities found thin films of lower energy and higher symmetry existed at increasedchain-chain separations.head-group bonding is therefore identified as a force for controlling monolayer order.Analysis of the natural monolayer structures on a silicon dioxide surface determined the favourable head-group structures,and allowed the topochemical polymerization of p-bis(butadiynyl)benzene monolayers to be rationalized.