Halldin Stenlid Joakim, Johansson Adam Johannes, Brinck Tore
Applied Physical Chemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Teknikringen 30, SE-100 44, Stockholm, Sweden.
Phys Chem Chem Phys. 2018 Jan 24;20(4):2676-2692. doi: 10.1039/c7cp06259a.
Using local DFT-based probes for electrostatic as well as charge transfer/polarization interactions, we are able to characterize Lewis basic and acidic sites on copper, silver and gold nanoparticles. The predictions obtained using the DFT-probes are compared to the interaction energies of the electron donating (CO, HO, NH and HS) and the electron accepting (BH, BF, HCl [H-down] and Na) compounds. The probes include the local electron attachment energy [E(r)], the average local ionization energy [Ī(r)], and the electrostatic potential [V(r)] and are evaluated on isodensity surfaces located at distances corresponding to typical interaction distances. These probes have previously been successful in characterizing molecular interactions. Good correlations are found between Lewis acidity and maxima in V(r), appearing as a consequence of σ-holes, as well as minima in E(r), of the noble metal nanoparticles. Similarly are Lewis basic sites successfully described by surface minima in V(r) and Ī(r); the former are indicative of σ-lumps, i.e. regions of enhanced σ-density. The investigated probes are anticipated to function as reliable tools in nanoparticle reactivity and interaction characterization, and may act as suitable descriptors in large-scale screenings for materials of specific properties, e.g. in heterogeneous catalysis. Because of the similarity between the noble metal nanoparticle's interactions with Lewis bases and the concepts of halogen and hydrogen bonding, a new class of bonds is introduced - regium bonds - taking place between a σ-hole of a Cu, Ag or Au compound and an electron donor.
使用基于密度泛函理论（DFT）的局部探针来研究静电以及电荷转移/极化相互作用，我们能够表征铜、银和金纳米颗粒上的路易斯酸碱性位点。将使用DFT探针获得的预测结果与给电子化合物（CO、HO、NH和HS）和吸电子化合物（BH、BF、HCl [H向下]和Na）的相互作用能进行比较。这些探针包括局部电子附着能[E(r)]、平均局部电离能[Ī(r)]和静电势[V(r)]，并在对应于典型相互作用距离的等密度表面上进行评估。这些探针此前已成功用于表征分子间相互作用。发现路易斯酸度与V(r)中的最大值之间存在良好的相关性，V(r)中的最大值是由σ-空穴导致的，同时与贵金属纳米颗粒的E(r)中的最小值也存在良好相关性。类似地，路易斯碱位点也可以通过V(r)和Ī(r)中的表面最小值成功描述；前者表示σ-团块，即σ-密度增强的区域。预计所研究的探针将成为纳米颗粒反应性和相互作用表征的可靠工具，并可作为大规模筛选具有特定性质材料（例如在多相催化中）的合适描述符。由于贵金属纳米颗粒与路易斯碱的相互作用与卤素键和氢键的概念相似，因此引入了一种新型的键——配位键——它发生在铜、银或金化合物的σ-空穴与电子供体之间。
