A relationship between the electride characteristics and the NLO properties is found: the more delocalization the excess electron of the electride experiences, the larger the β0 value is.

The design of stable organic electrides with high nonlinear optical (NLO) properties is a challenge in organic and materials chemistry. Here we theoretically design of a novel organic molecular electride model, Li + (C 20 H 15 Li 5 )e − , by modifying the lithiation and Li-doping based on dodecahedrane (C 20 H 20 ). Its electride characteristic is verified by the quantum theory of atoms in molecules and electron localization function analyses. For the first time, the strategy of steric protection is applied to improve the stability of the organic electride Li + @(C 20 H 15 Li 5 )e − , in which the closed C 20 cage serves not only as the ligand with a negative inner electric field to stabilize the Li cation but also as a barrier to prevent the Li cation from escaping. Meanwhile, the released excess electron is firmly captured in the cavity of Li 5 . Moreover, Li + (C 20 H 15 Li 5 )e − displays a remarkably large first hyperpolarizability of 1.4 × 10 4 au with potential application in organic second-order NLO materials.Electrides are a novel kind of ionic compounds in which electrons serve as anions, and considered to have potential applications in nonlinear optics. Here, a new and stable organic electride, Li@C 20 H 15 Li 5 , was theoretically designed based on dodecahedrane (C 20 H 20 ). First, five H atoms in one five-membered carbon ring of C 20 H 20 are substituted by five Li atoms to form the Li salt (C 20 H 15 ) δ-(Li 5 ) δ+ with the large dipole moment of 9.6 D, forming the molecular field. Second, an additional Li atom is encapsulated in the cage, and the valence electron of Li is polarized in the molecular field of C 20 and then pushed outside the cage to give rise to the excess electron, which is captured by the cavity formed by five Li atoms to form the electride Li + (C 20 H 15 Li 5 )e − . Additionally, in the dimer of the electride Li@C 20 H 15 Li 5 , both the Li cation and the electron are sealed in the carbon and Li cages, effectively improving the stability of the electride. In addition, the electride characteristics of the monomer and dimer were verified by the topology AIM and ELF. This electride has a remarkably large first hyperpolarizability and thus may be a promising building block for high-performance NLO materials based on electrides. ACKNOWLEDGEMENTS

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