Exploration of Molecular Materials based on Cooperative Proton-Electron Systems

基于质子与电子的协同作用，人们已经开始寻找新的分子材料。我们制定了探索新分子材料的总体策略。氢键电荷转移(HBCT)体系中的协同质子-电子转移(PET)可能产生氢键中性自由基的分子组装。这类PET体系的固态性质取决于质子-电子协作性的类型和强度。分子水平的考虑导致了两个合理的分子设计策略：探索具有较小分子间CT间隙的新的电子系统和通过电子修饰来稳定氢键中性自由基态。根据这些策略，我们合成了新的PET体系：(1)给体和受体取代的喹氢酮，(2)扩展的共轭喹氢酮，以及(3)具有氢键网络的过渡金属络合物。例如，对于方法(1)，我们通过引入电子给体和受体取代基对原型苯并喹氢酮进行了修饰。至于(2)，我们合成了扩展共轭的萘基、联苯基和二苯基的喹氢酮。在这些喹氢酮中，我们发现了氢键和CT相互作用之间的协同现象。为了扩展PET系统，现在正在积极进行新的方法(3)。在氢键过渡金属络合物中，我们可以利用金属原子氧化还原性质的附加特性以及金属原子之间或金属原子与配体之间的分子间相互作用。作为第一步，我们成功地构建了双咪唑过渡金属配合物的氢键二聚体模型。我们现在集中精力构建双咪唑型和蝶烷型过渡金属络合物的新的氢键分子体系。

Search for new molecular materials based on the cooperative interactions between proton and electron has been performed. We developed a general strategy to explore new molecular materials. Cooperative proton-electron transfer (PET) in the hydrogen-bonded charge transfer (HBCT) systems might produce a molecular assembly of H-bonded neutral redicals. The solid state properties of such PET systems depend on the type and strength of the proton-electron cooperativity. A molecular level consideration leads to two reasonable molecular design strategies : the exploration of new electronic systems having smaller intermolecular CT gap and an electronic modification to stabilize H-bonded neutral radical state. According to the strategies, we synthesized new PET systems : (1) the donor and acceptor substituted quinhydrones, (2) the extended conjugated quinhydrones, and (3) the transition metal complexes having H-bonding networks. For example, as for the approach (1), we modified the prototype benzoquinhydrone by introducing the electron donor and the acceptor substituents. As for (2), we synthesized naphtho-, bipheno-, and stilben-quinhydrone as extended conjugated quinhydrones. In these quinhydrones, we have found cooperative phenomena between H-bonding and CT interaction. In order to expand the PET systems, new approach (3) are now actively performed. In the H-bonded transition metal complexes, we can utilize the additional characteristics of redox properties of the metal atoms and the intermolecular interactions between the metal atoms or between the metal atom and the ligand. As a first step, we succeeded to construct a H-bonded dimer model of the biimidazole transition metal complex. We are now concentrated to construct new H-bonded molecular systems of biimidazole-type and pteridine-type transition metal complexs.