A new strategy for simultaneously enhancing nonlinear optical response and electron stability in novel cup–saucer+–cage−-shaped sandwich electride molecules with an excess electron protected inside the cage

Abstract

Novel cup–saucer–cage-shaped sandwich electride molecules calix[4]pyrrole⋯K₃O⁺⋯e@C_nF_n⁻, (n = 8, 10, 14, 20, and 36) with an excess electron protected inside the C_nF_n cage are constructed theoretically. In the sandwich structures, the below calix[4]pyrrole cup pushes the valence electron of the sandwiched superalkali atom K₃O saucer, forming an excess electron, which is further pulled and protected inside the above C_nF_n cage, thus an electron-transfer relay occurs. In particular, owing to the unusual electron transfer, an unusual and fortunate phenomenon is discovered that increasing the C_nF_n cage size enhances not only the nonlinear optical response (β₀), but also the electron stability (VIP). Thus, a new strategy of simultaneously enhancing β₀ and VIP values is found for the first time, namely by increasing the C_nF_n cage size in novel cup–saucer–cage-shaped sandwich electride molecules, with the excess electron protected inside the cage.