Tachikawa Hiroto, Lund Anders
Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden.
Phys Chem Chem Phys. 2022 May 4;24(17):10318-10324. doi: 10.1039/d1cp04638a.
Coronene (CH), a charge transfer complex with low-cost and high-performance energy storage, has recently attracted attention as a model molecule of graphene nano-flakes (GNFs). The stacking structures of the trimer radical cation correlate strongly with the conduction states of the GNFs. In the present paper, the structures and electronic states of the monomer, dimer and trimer radical cations of coronene were investigated by means of density functional theory calculations. In particular, the proton hyperfine coupling constants of these species were determined. The radical cation of coronene (monomer) showed two structures corresponding to the A and B states due to the Jahn-Teller effect. The A state was more stable than the B state, although the energy difference between the two states was only 0.03 kcal mol. The dimer and trimer radical cations took stacking structures distorted from a full overlap structure. The intermolecular distances of the molecular planes were 3.602 Å (dimer) and 3.564 and 3.600 Å (trimer). The binding energies of the dimer and trimer were calculated to be 8.7 and 13.3 kcal mol, respectively. The spin density was equivalently distributed on both coronene planes in the dimer cation. In contrast, the central plane in the trimer cation had a larger spin density, = 0.72, than the upper and lower planes, both with = 0.14. The proton hyperfine coupling constants calculated from these structures and the electronic states of the monomer, dimer, and trimer radical cations of coronene were in excellent agreement with previous ESR spectra of coronene radical cations. The structures and electronic states of (coronene) ( = 1-3) were discussed on the basis of the theoretical results.
蒄（CH）作为一种具有低成本和高性能储能的电荷转移复合物，最近作为石墨烯纳米片（GNFs）的模型分子受到了关注。三聚体自由基阳离子的堆积结构与GNFs的导电状态密切相关。在本文中，通过密度泛函理论计算研究了蒄的单体、二聚体和三聚体自由基阳离子的结构和电子态。特别地，确定了这些物种的质子超精细耦合常数。由于 Jahn-Teller 效应，蒄的自由基阳离子（单体）显示出对应于 A 态和 B 态的两种结构。A 态比 B 态更稳定，尽管这两种状态之间的能量差仅为 0.03 kcal/mol。二聚体和三聚体自由基阳离子采取了从完全重叠结构扭曲的堆积结构。分子平面的分子间距离分别为 3.602 Å（二聚体）和 3.564 Å 以及 3.600 Å（三聚体）。计算得出二聚体和三聚体的结合能分别为 8.7 和 13.3 kcal/mol。在二聚体阳离子中，自旋密度在两个蒄平面上等效分布。相比之下，三聚体阳离子的中心平面具有比上下平面更大的自旋密度，分别为 = 0.72 和 = 0.14。从这些结构以及蒄的单体、二聚体和三聚体自由基阳离子的电子态计算得到的质子超精细耦合常数与之前蒄自由基阳离子的电子自旋共振（ESR）光谱结果非常吻合。基于理论结果讨论了（蒄）（ = 1 - 3）的结构和电子态。
