Designing a new class of excess electron compounds with unique electronic structures and extremely large non-linear optical responses

• Published in: New journal of chemistry Vol. 44; no. 16; pp. 6411 - 6419
• Main Authors: Li, Xiang-Hui, Zhang, Li, Zhang, Xiao-Ling, Ni, Bi-Lian, Li, Chun-Yan, Sun, Wei-Ming
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 28.04.2020
• Subjects: Alkali metals; Calcium; Cartesian coordinates; Electric fields; Electrons; Lithium; Magnesium; Mathematical analysis; Sodium
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d0nj00896f

An intriguing class of excess electron compounds with unique electronic structures was obtained on the basis of a facially polarized molecule, namely, all- cis -1,2,3,4,5,6-hexafluorocyclohexane ( 1 ). By doping two different faces of this Janus molecule with an alkaline earth atom and an alkali-metal atom, a series of M- 1 -M′ (M = Be, Mg, and Ca; M′ = Li, Na, and K) compounds were first constructed. The calculated results show that unlike Be and Mg, one 4s electron of Ca in Ca + - 1 -M′ − (M′ = Li, Na, and K) can be transferred to the upper alkali metal atom, thus forming an alkali metal anion, while the remaining 4s electron of Ca is pushed away from Ca + , yielding localized electrons around it by the instinctive facial polarization of 1 or with the assistance of oriented external electric fields (OEEFs). Interestingly, these novel compounds exhibit extremely large first hyperpolarizabilities ( β 0 ) in the range of 9.94 × 10 5 -1.81 × 10 6 a.u. and high stability. Thus, this work can provide first members simultaneously containing typical alkalide features and electride-like characteristics to further enrich the family of excess electron compounds and offer novel candidates for NLO materials with high performance. New Ca + - 1 -M′ − (M′ = Li, Na, and K) compounds with typical alkalide features and electride-like characteristics have been obtained.