From an electride-like super alkali earth atom to a superalkalide or superalkali electride: M(HF)3M (M = Na or Li) as field-induced excellent inorganic NLO molecular switches

Exploration of novel molecular switches is an ongoing hot issue in molecular electronics. Alkalides and electrides are two typical representatives of excess electron compounds. It was found that M(HF)3M (M = Li or Na) induced by an oriented external electric field are good candidates for inorganic multi-response nonlinear optical (NLO) molecular switches. Their off forms (C3h) exhibit electride-like super alkali earth atom characteristics, while their on forms (C3v) exhibit charming superalkalide (M = Na or Li) or superalkali electride characteristics (M = Li). The increases of the static first hyperpolarizabilities (βe0) from off to on forms constitute a 2–3 orders of magnitude improvement for both M = Li and Na. These extremely large differences in βe0 reinforce the potential of M(HF)3M for applications in excellent multi-response nonlinear optical materials.