Novel Columnar Liquid-Crystalline Nanomaterials Designed toward Anhydrous Organic Proton Conductors

摘要

Urea derivative with double long alkyl chains and the corresponding rare-earth metal complex were prepared and their thermotropic liquid-crystalline behavior was evaluated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffractometry, electron microscopy. It was found that in spite of the compounds without disk-like molecular shape, they exhibit a columnar phase with two-dimensional rectangular lattice in which each column is built up from one-dimensional molecular chains, i.e., non-covalently linked polymer architectures on the basis of one-dimensional hydrogen bond. In the columnar liquid-crystalline materials, we predicted that delocalization of protons along the one-dimensional self-assembled molecular chains is induced, resulting in useful channels for prototropy. To verify this prediction, we evaluated preliminarily the electric conductivity of the urea liquid-crystalline thin films by electrochemical impedance spectroscopy. The solid-state films retaining a columnar structure showed a protonic conductivity even under dry conditions.