Doping alkali metal ions and introducing electron donor groups to fulleropyrrolidine derivatives: Large second-order nonlinear optical responses

The present study is focused on the nature of the structure-properties relationships of 2,5-diaryl fulleropyrrolidine derivatives. 2,5-diaryl fulleropyrrolidines modified by electron donor groups, and doped endohedrally with alkali metal ions (M@1-D, D = –CH3, –OCH3, –NH2; M = Li+, Na+, K+) are designed and investigated. Surprisingly, the K@1-NH2 shows remarkable NLO response. [Display omitted] •The 2,5-Diaryl fulleropyrrolidine derivatives are designed and investigated.•M@1-D shows remarkable NLO response compared to 1-D and M@1.•The K+@1-NH2 possesses the largest βtot value of 4.58 × 103 a.u..•Uv–vis absorption spectrum explains tendency of the βtot value. The present study is focused on the nature of the structure-properties relationships of the 2,5-diaryl fulleropyrrolidine (1) derivatives by the density functional theory (DFT). 1 derivatives are designed and investigated, which are modified by electron donor groups and doped with alkali metal ions (1-D, M@1 and M@1-D, D = –CH3, –OCH3, –NH2; M = Li+, Na+, K+). Surprisingly, M@1-D compounds show a remarkable NLO response compared to 1-D and M@1. The K+@1-NH2 possesses the largest βtot value of 4.58 × 103 a.u.. Furthermore, the Uv–vis absorption spectrum by the time-dependent (TD-DFT) method is carried out to study tendency of the NLO responses for 1-D, M@1 and M@1-D. Calculated maximum absorption wavelength of K+@1-NH2 is significantly red-shifted compared to 1-NH2 and K+@1. The current work presents that 2,5-diaryl fulleropyrrolidine modified by introducing electron donor groups and doping alkali metal ions is a good candidate for well-performance NLO nanomaterial.