Widening or Lengthening? Enhancing the First Hyperpolarizability of Tubiform Multilithium Salts

Abstract

Very recently, tubiform multilithium salts have been investigated as new candidates for high-performance nonlinear optical (NLO) materials because of their large static first hyperpolarizability (β0) (J. Phys. Chem. C 2009, 113, 4984−4986). The interesting question of how to further enhance the β0 value of the multilithium salt, by widening or lengthening the tubiform cyclacene, is studied in this work. On one hand, the effect of widening on the β0 value of tubiform multilithium salts is investigated using Lin-[n]cyclacene (n = 5–8). We found that the β0 value (15497 au) of Li8-[8]cyclacene is 3 times larger than the 5028 au value of the Li5-[5]cyclacene, with the total number of carbon atoms increasing from 20 to 32. On the other hand, lengthening Li5-[5]cyclacene to form Li5–CNT (5,0) results in the dramatically enhanced β0 value of 146642 au, which is 29 times larger than the value for the Li5-[5]cyclacene, even though the total number of carbon atoms is increased only from 20 to 30. Further, the secon...