Efficient External Electric Field Manipulated Nonlinear Optical Switches of All-Metal Electride Molecules with Infrared Transparency: Nonbonding Electron Transfer Forms an Excess Electron Lone Pair

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• 作者：Hui-Min He ; Ying Li ; Hui Yang ; Dan Yu ; Si-Yi Li ; Di WuJian-Hua Hou ; Rong-Lin Zhong ; Zhong-Jun Zhou ; Feng-Long Gu ; Josep M. Luis ; Zhi-Ru Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：958-968
• 全文大小：610K
• ISSN：1932-7455

文摘

Focusing on the interesting new concept of all-metal electride, centrosymmetric molecules e<sup>–sup>+M<sup>2+sup>(Ni@Pb<sub>12sub>)<sup>2–sup>M<sup>2+sup>+e<sup>–sup> (M = Be, Mg, and Ca) with two anionic excess electrons located at the opposite ends of the molecule are obtained theoretically. These novel molecular all-metal electrides can act as infrared (IR) nonlinear optical (NLO) switches. Whereas the external electric field (F) hardly changes the molecular structure of the all-metal electrides, it seriously deforms their excess electron orbitals and average static first hyperpolarizabilities (β<sub class="stack">0sub><sup class="stack">esup>(F)). For e<sup>–sup>+Ca<sup>2+sup>(Ni@Pb<sub>12sub>)<sup>2–sup>Ca<sup>2+sup>+e<sup>–sup>, a small external electric field F = 8 × 10<sup>–4sup> au (0.04 V/Å) drives a long-range excess electron transfer from one end of the molecule through the middle all-metal anion cage (Ni@Pb<sub>12sub>)<sup>2–sup> to the other end. This long-range electron transfer is shown by a prominent change of excess electron orbital from double lobes to single lobe, which forms an excess electron lone pair and electronic structure Ca<sup>2+sup>(Ni@Pb<sub>12sub>)<sup>2–sup>Ca<sup>2+sup>+2e<sup>–sup>. Therefore, the small external electric field induces a dramatic β<sub class="stack">0sub><sup class="stack">esup>(F) contrast from 0 (off form) to 2.2 × 10<sup>6sup> au (on form) in all-metal electride molecule Ca(Ni@Pb<sub>12sub>)Ca. Obviously, such switching is high sensitive. Interestingly, in the switching process, such long-range excess electron transfer does not alter the valence and chemical bond nature. Then, this switching mechanism is a distinct nonbonding evolution named electronic structure isomerization, which means that such switching has the advantages of being fast and reversible. Besides, these all-metal electride molecules also have a rare IR transparent characteristic (1.5–10 μm) in NLO electride molecules, and hence are commendable molecular IR NLO switches. Therefore, this work opens a new research field of electric field manipulated IR NLO switches of molecular all-metal electrides.