Design of functional solids employing pi-electron systems connected with hydrogen-bonds

点击翻译按钮获取中文摘要

Hydrogen-bonded systems, in which the proton transfer is coupled with the pi-electron configurational change, are the subject of this study. If the interaction between the molecules is sufficiently strong in the crystalline state, the proton motion is expected to modulate the electronic properties of the crystal. In this research project, structures and physical properties of intra-and inter-molecular hydrogen-bonded systems have been investigated to explore the possibilities of constructing novel functional solids based on the proton transfer.1. N-Salicylideneaniline derivatives and their charge transfer complexes have been selected for the intramolecular hydrogen-bonded system. From X-ray analyses of the OH・・・N hydrogen-bond structures, it has been confirmed that the equilibrium position of the proton changes by chemical modification of the molecule or by the strength of the charge-transfer interaction operating between molecules. This structural change can also be verified from the … More differences in their thermochromic behavior and in their infrared spectra. From the measurements of the NMR relaxation time of^1H, the proton dynamics has been found to depend strongly on the structural change in the hydrogen bond by chemical modification. Since the coupling between the proton motion and conduction electrons is expected to lead a novel type of electrical properties, various derivatives have been employed as a donor component for preparing charge transfer complexes. Although no highly conducting single crystals have been obtained yet, it has been found that some combinations yield conducting powder. Efforts for the crystal growth will be continued.2. Some compounds which belong to the intermolecular hydrogen-bonded system, which are composed of aromatic amines and TCNQ type or benzoquinone type acceptors, have been found to be highly conducting. However, most of them have a mixed-type stacking structure, which is quite different from typical conductors. It has also been found that some complexes can be converted from non-conducting to conducting state by heat treatment. Although DAP-TCNQ(DAP; 1,6-pyrenediamine), which is the only complex which has a segregated-type stacking structure, has been found to show high conductivity at room temperature, the activation energy of conduction is anomalously high. Elucidation of the relation between these unique phenomena found and the hydrogen-bonding will be the next step of this study. Less