Bergmeister Stefan, Kollotzek Siegfried, Calvo Florent, Gruber Elisabeth, Zappa Fabio, Scheier Paul, Echt Olof
Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, A-6020 Innsbruck, Austria.
Laboratoire Interdisciplinaire de Physique, CNRS, Université Grenoble Alpes, F-38000 Grenoble, France.
Molecules. 2022 Aug 3;27(15):4937. doi: 10.3390/molecules27154937.
The adsorption of helium or hydrogen on cationic triphenylene (TPL, CH), a planar polycyclic aromatic hydrocarbon (PAH) molecule, and of helium on cationic 1,3,5-triphenylbenzene (TPB, CH), a propeller-shaped PAH, is studied by a combination of high-resolution mass spectrometry and classical and quantum computational methods. Mass spectra indicate that HeTPL complexes are particularly stable if = 2 or 6, in good agreement with the quantum calculations that show that for these sizes, the helium atoms are strongly localized on either side of the central carbon ring for = 2 and on either side of the three outer rings for = 6. Theory suggests that HeTPL is also particularly stable, with the helium atoms strongly localized on either side of the central and outer rings plus the vacancies between the outer rings. For HeTPB, the mass spectra hint at enhanced stability for = 2, 4 and, possibly, 11. Here, the agreement with theory is less satisfactory, probably because TPB is a highly fluxional molecule. In the global energy minimum, the phenyl groups are rotated in the same direction, but when the zero-point harmonic correction is included, a structure with one phenyl group being rotated opposite to the other two becomes lower in energy. The energy barrier between the two isomers is very small, and TPB could be in a mixture of symmetric and antisymmetric states, or possibly even vibrationally delocalized.
通过高分辨率质谱以及经典和量子计算方法相结合，研究了氦气或氢气在阳离子型三亚苯（TPL，CH）（一种平面多环芳烃（PAH）分子）上的吸附，以及氦气在阳离子型1,3,5 - 三苯基苯（TPB，CH）（一种螺旋桨状PAH）上的吸附。质谱表明，当 = 2或6时，HeTPL络合物特别稳定，这与量子计算结果高度一致，量子计算表明，对于这些尺寸，当 = 2时，氦原子强烈定位于中心碳环的两侧，当 = 6时，氦原子强烈定位于三个外环的两侧。理论表明，HeTPL也特别稳定，氦原子强烈定位于中心环和外环的两侧以及外环之间的空位处。对于HeTPB，质谱暗示当 = 2、4以及可能 = 11时稳定性增强。在这里，与理论的一致性不太令人满意，可能是因为TPB是一种高度易变的分子。在全局能量最小值处，苯基沿相同方向旋转，但当包含零点谐波校正时，一个苯基与另外两个苯基反向旋转的结构能量更低。两种异构体之间的能垒非常小，TPB可能处于对称和反对称状态的混合态，甚至可能是振动离域态。
