Influence of the Complexation of Sodium and Lithium Triflate on the Self-Assembly of Tubular-Supramolecular Architectures Displaying a Columnar Mesophase Based on Taper-Shaped Monoesters of Oligoethyleneoxide with 3,4,5-Tris(p-(n-dodecan-l-yloxy)benzyloxy)benzoic Acid and of Their Polymethacrylates.

摘要

The monoesters of mono-(la), di(lb), tri(1c) and tetra(ld) ethylene glycol with 3,4,5-tris(p-(n-dodecan-1-yloxy)benzyloxy)benzoic acid (1), the polymethacrylates derived from them (2) and the complexes of both 1 and 2 with LiCF3SO3 and NaCF3SO3 self-assemble into cylindrical supramolecular architectures which exhibit a hexagonal columnar (Phi sub h) mesophase. The generation of the Phi sub h mesophase depends on the stabilization of this assembly by endo-recognition in the core of the cylinder (H-bonding and ionic interactions) and exo-recognition that occurs between the tapered groups and also between the cylinders (i.e., the hexagonal arrangement of the columns). The low molecular weight compounds 1 are able to complex more salt in the Phi sub h mesophase and have larger increases in (Phi sub h-isotropic transition temperature (T Phi sub h-i) per increase in salt concentration than the corresponding polymethacrylates 2 derived from them. Molecular modeling appears to indicated that positional and conformational restrictions imposed by both the tapered side groups and the polymer backbone are responsible for these results. Both the polymers and the low molar mass compounds have their T Phi sub h-i shifted to lower temperatures and allow more LiCF3SO3 to be complexed with the increase in the number of oxyethylene segments present in the flexible spacer. A comparison of the difference in the effectiveness Of the Li cation versus the Na cation in providing an increased stabilization of the Phi sub h mesophase does not show any significant differences between the two cations.