Conjugated Assembly of Viologens with Spin Manipulation

在一些具有光电化学活性的吡啶单元的偶联组装中报道了多步氧化还原过程，从而导致功能集成的分子组装。(1)芳烯连接的紫蛋白二聚体呈现出单自由基、三重双自由基、半醌和全醌结构受光电化学控制的四步还原过程。(2)双齿吡啶基吡啶配体与顺磁性金属离子的配位组装通过中间的吡啶基自由基的反铁磁耦合表现出光化学可调的自旋有序。(3)各种双（吡啶）-β-二酮金属配合物及其盘状柱状结构均具有d-π依赖的多步氧化还原过程。讨论了相互作用路径分析，为今后的分子电子通信器件提供了指导。有趣的是，两种吡啶基自由基的配体间反式构型和配体内构型均证实了三重态基态，而配体间顺式构型为热激三重态，即基态为单线态双自由基。通过在聚芳基异氰酸酯中精确制造吡啶单元，介绍了螺旋共轭聚合物几何和电子结构的电化学控制。此外，还将引入吡啶衍生物的阳极亲核取代来修饰导电聚合物。设计良好的配位聚合物的研究取得了显著进展，在超分子化学中占据了主要地位，它通过小构件的自组装提供了几十纳米尺度的各种纳米结构。

Multi-step redox processes are reported in several it-conjugated assemblies of photoelectrochemically active pyridinium units, leading to function-integrated molecular assembly. The strategy has been set to strongly link each redox active unit and then to understand the correlated redox properties, (1) The arylene-linked viologen dimers showed four-step reduction processes in which mono-radical, triplet diradical, half and full quinoid structures are controlled photoelectrochemically. (2) The coordination assembly of bidentate pyridyl pyridinium ligands with paramagnetic metal ions exhibited photochemically tunable spin ordering through antiferromagnetic coupling of the intervening pyridyl radicals. (3) The d-π-dependent multi-step redox processes were demonstrated in various bis(pyridinio)-β-diketone metal complexes, together with their discotic columnar structures. The interaction path analysis giving a guideline for the coming molecular devices with electronic communication will be discussed. Interestingly, triplet ground state was confirmed in inter-ligand trans-configuration and intra-ligand configuration of two pyridinylradicals, while the inter-ligand cis-configuration was thermally excited triplet state, i.e., singlet biradical in the ground state. The electrochemical control of both geometric and electronic structures of the helical conjugated polymers will be also introduced by precisely fabricating pyridinium units in poly (arylisocyanide). Additionally, new modification of conducting polymers will be also introduced by anodic nucleophilic substitution of pyridine derivatives. Remarkable progress has been made in the study of well-designed coordination polymers to take the major place in supramolecular chemistry, which is providing various kinds of nano-structures, in several-to-decades nanometer scales, by self-assembly of small building blocks.