The Alkaline-earthides based parallel-stacked dimer and trimer of Janus face C6H6F6 showing extremely large nonlinear optical responses

Abstract

To research the aggregate effect on first hyperpolarizability (β0), we selected the dimer (2) and trimer (3) of all-cis 1,2,3,4,5,6-hexafluorocyclohexane C6H6F6 (1) in their parallel-stacked conformations as two ligands. And a series of excess electron compounds MA-2-MAE and MA-3-MAE (MA = Li, Na and K; MAE = Be, Mg and Ca) were successfully designed by doping alkali metal atom and alkaline-earth metal atom into the 2 or 3. In this work, we studied the geometric structures, electronic structures and NLO properties of MA-2-MAE and MA-3-MAE compounds by density functional theory (DFT). The HOMO orbitals analysis showed that MA-2-MAE and MA-3-MAE are alkaline-earthides. Among these alkaline-earthides, the largest β0 of the Li-3-Be is 1.46 × 107 au, which is almost 21 times larger than those values of M-C6H6F6 (M = Li, Na and K) (7.00 × 105 au). We sincerely hope this work will not only enrich the variety of excess electron compounds but also further reveal the impact of aggregate effect.