Effects of the cage unit size and number of cage units as well as bridge unit on the second order nonlinear optical response in multicage electride molecules.

Interesting effects of the cage unit size and number of cage units as well as bridge unit on the static first hyperpolarizabilities (β0) for novel multicage electrides are revealed. (1) The small cage unit C8 systems have larger β0 for cage unit size effect. (2) The β0 increases with increasing cage unit number. (3) The effect of the bridge between cage units on β0 is O > NH > CH2. Specially, a novel relationship between the excess electron cloud and β0 is revealed. Assembling the three effects, the constructed multicage electride structure with three small C8 cage units connected by the O-bridge (K···3C8(O)) is a electride salt K(+)[e@3C8(O)](-) and has the considerable β0 value of 7.1 × 10(5) au, which is about 55 times larger than the 13 000 au of the single-cage electride molecule Na3O(+)(e@C20F20)(-). The novel multicage strategy is effective to enhance nonlinear optical (NLO) response.