Laboratoire de Chimie Inorganique Rédox, Département de Chimie Moléculaire, Université Joseph Fourier/CNRS, Grenoble, France.
J Am Chem Soc. 2012 Feb 8;134(5):2653-71. doi: 10.1021/ja209766e. Epub 2012 Jan 18.
Rotational motions of ferrocene-based carousels have been achieved by electron transfer centered on π-dimerizable 4,4'-bipyridinium substituents introduced on both cyclopentadienyl rings through covalent linkers of different size, geometry, and flexibility. Detailed spectroscopic, electrochemical, and theoretical analyses demonstrate that rigid and fully conjugated linkers allow the quantitative formation of intramolecular π-dimers resulting from optimized orbital overlaps within the HOMO of the electrochemically generated bis-radical species. The tetra-cationic "charge-repelled" conformers, the self-assembled π-dimers, and their electron triggered interconversions have been investigated by UV-vis, NMR, and ESR spectroscopy, electrochemistry, X-ray diffraction analysis, and theoretical calculations. These studies support the conclusion that the rotation of both cyclopentadienyl rings in ferrocene can be controlled electrochemically using noncovalent reversible interactions arising from π-radical coupling processes.
通过在两个茂环上通过不同大小、几何形状和柔性的共价连接体引入可π-二聚的 4,4'-联吡啶取代基，实现了基于二茂铁的旋转木马的电子转移中心的旋转运动。详细的光谱、电化学和理论分析表明，刚性和完全共轭的连接体允许定量形成分子内π-二聚体，这是由于电化学生成的双自由基物种的 HOMO 内轨道重叠得到优化。通过 UV-vis、NMR 和 ESR 光谱、电化学、X 射线衍射分析和理论计算研究了四阳离子“电荷排斥”构象、自组装的π-二聚体及其电子触发的互变异构。这些研究支持这样的结论，即使用源自π-自由基偶联过程的非共价可逆相互作用，可以通过电化学控制二茂铁中环戊二烯基环的旋转。
