Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
Phys Chem Chem Phys. 2013 Feb 14;15(6):1918-28. doi: 10.1039/c2cp43627b. Epub 2012 Dec 20.
We report results of quantum chemical calculations for the neutral and anionic species of (4,4')-bipyridine (44BPY), a prototypical molecule with a floppy degree of freedom, placed in vacuo and in solvents. In addition to equilibrium geometries and vibrational frequencies and spectra, we present adiabatic energy curves for the vibrational modes with significant intramolecular reorganization upon charge transfer. Special attention is paid to the floppy strongly anharmonic degree of freedom of 44BPY, which is related to the most salient structural feature, namely the twist angle θ between the two pyridine rings. The relevance of the present results for molecular transport will be emphasized. We show that the solvent acts as a selective gate electrode and propose a scissor operator to account for solvent effects on molecular transport. Our result on the conductance G vs. cos(2)θ is consistent with a significant transmission in perpendicular conformation indicated by previous microscopic analysis.
我们报告了（4,4'）-联吡啶（44BPY）中性和阴离子物种的量子化学计算结果，44BPY 是一个具有柔软自由度的典型分子，存在于真空中和溶剂中。除了平衡几何形状和振动频率和光谱外，我们还展示了在电荷转移时具有显著分子内重排的振动模式的绝热能曲线。特别关注 44BPY 的柔软强非谐自由度，这与最显著的结构特征有关，即两个吡啶环之间的扭转角θ。我们将强调当前结果对于分子输运的相关性。我们表明，溶剂充当选择性门电极，并提出了一个剪刀算子来解释溶剂对分子输运的影响。我们关于电导 G 与 cos(2)θ 的结果与以前的微观分析所表明的垂直构象中的显著传输一致。
