Conjugated Assembly of Viologens with Spin Manipulation

报道了几种光电化学活性吡啶单元的共轭组装体中的多步氧化还原过程，导致功能集成的分子组装体。（1）亚芳基连接的紫精二聚体表现出四步还原过程，其中单自由基、三重双自由基、半醌和全醌结构受光电化学控制。(2)双齿吡啶吡啶配体与顺磁性金属离子的配位组装表现出光化学可调的自旋有序通过反铁磁耦合的介入吡啶基自由基。(3)在各种双（吡啶）-β-二酮金属配合物中发现了依赖于d-π的多步氧化还原过程，以及它们的分散柱状结构.讨论了相互作用路径分析对未来具有电子通讯功能的分子器件的指导作用。有趣的是，在两个吡啶基自由基的配体间反式构型和配体内构型中证实了三重基态，而配体间顺式构型是热激发三重态，即，基态的单线态双自由基。螺旋共轭聚合物的几何结构和电子结构的电化学控制也将通过精确地制造在聚（芳基异氰）吡啶单元。此外，吡啶衍生物的阳极亲核取代反应也将为导电聚合物的改性带来新的进展。设计良好的配位聚合物的研究已经取得了显著的进展，在超分子化学中占据了主要地位，它通过小的构建块的自组装提供了各种纳米结构，在几个到几十个纳米尺度。

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.