Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene.
Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene.
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DOI：
10.1021/acsnano.5b06153
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发表时间：
2016-02
期刊：
影响因子：
17.1
通讯作者：
N. Néel;M. Lattelais;M. Bocquet;J. Kröger
中科院分区：
文献类型：
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作者：
N. Néel;M. Lattelais;M. Bocquet;J. Kröger
用扫描隧道显微镜进行的单分子化学主要是在金属表面上进行的。然而，分子-金属杂化往往不利于真正的分子性质，并掩盖了它们在化学反应中的变化。我们在Ir(111)表面使用石墨烯来降低Ir(111)与被吸附的酞菁分子之间的耦合。通过扫描隧道显微镜尖端的局域电子注入，将两个吡咯氢原子从单一的酞菁类化合物中移除。H原子对的脱离引起了分子电子结构的强烈改变，但吸附几何构型没有改变。微分电导的光谱和图谱与密度泛函计算相结合，揭示了H抽出时最高占据分子轨道的全部退居现象。完整分子的占据π态被认为是通过分子内电子转移到无氢氮原子的悬挂σ态而被清空的。
Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.