Theoretical Study of the Substituent Effects on the Nonlinear Optical Properties of a Room-Temperature-Stable Organic Electride.

Excess-electron compounds can be considered as novel candidates for nonlinear optical (NLO) materials because of their large static first hyperpolarizabilities (ß0 ). A room-temperature-stable, excess-electron compound, that is, the organic electride Na@(TriPip222), was successfully synthesized by the Dye group (J. Am. Chem. Soc. 2005, 127, 12416). In this work, the ß0 of this electride was first evaluated to be 1.13×106  au, which revealed its potential as a high-performance NLO material. In particular, the substituent effects of different substituents on the structure, electride character, and NLO response of this electride were systemically studied for the first time by density functional theory calculations. The results revealed that the ß0 of Na@(TriPip222) could be further increased to 8.30×106  au by introducing a fluoro substituent, whereas its NLO response completely disappeared if one nitryl group was introduced because the nitro-group substitution deprived the material of its electride identity. Moreover, herein the dependence of the NLO properties on the number of substituents and their relative positions was also detected in multifluoro-substituted Na@(TriPip222) compounds.