Third-order nonlinear optical property contrast as self-assembly recognition for nanorings⊃C60

Abstract

Nonlinear optical (NLO) switches have been probed aiming at the improvement of the storage capacity of optical memories. Recently, large NLO contrasts have been proposed for characterization and detection processes. To extend the application of high NLO contrasts to other important aspects, the third-order NLO contrast of host–guest nanorings⊃C₆₀ tuned by self-assembly was studied in this work. The calculated third-order NLO responses showed that contrasts were displayed on the γ values between the nanoring and nanorings⊃C₆₀. In particular, the γ value (3919 × 10⁻³⁶ esu evaluated at the ωB97XD/6-31+G(d) level) of [6]CPT⊃C₆₀ is 23.2 times as large as that of [6]CPT (169 × 10⁻³⁶ esu). The TDDFT calculations further demonstrated that the large third-order NLO response can be enlarged by self-assembly, and the nature of the nanorings⊃C₆₀ with a larger third-order NLO response is mainly due to the π → π* transition of the nanoring and weak charge transfer from the nanoring to C₆₀.