The electronic structures and nonlinear optical properties of Alkali and Alkali earth metal atoms doped C6H6Cl6: A density functional theoretical study

The all-cis 1,2,3,4,5,6-hexafluorocyclohexane C6H6F6 (1) is a well-known molecule which has an unusually large molecular dipole moment (6.2 Debye), and plentiful novel excess electron compounds have been successfully designed on the basis of it recently. Inspired by 1, in this study, we tried to replace all the F atoms in molecule C6H6F6 with Cl atoms and obtained the all-cis 1,2,3,4,5,6-hexachlorocyclohexane C6H6Cl6 (2). By introducing alkali metal atoms and alkaline earth metal atoms, a novel series of alkalides and excess electron compounds, namely MA*+ -2 -MA- (MA* = Na, K; MA = Li, Na and K) and MA*-2-MAE (MA* = Na, K; MAE = Be, Mg and Ca), were theoretically constructed and studied in this work. Our results exhibit the apparent charge transfer in MA*+ -2 -MA- systems by NBO analysis. And these compounds all show good stability from the values of VIE and Gap. Especially, Na+-2-Li- compound exhibit the largest first hyperpolarizability value (3.4 x 106 au). The calculated results indicate these novel proposed species possess significantly large nonlinear optical responses. We hope this work will attract more experimental interests and efforts to design and synthesize new excellent NLO materials.