Intramolecular photo-induced electron transfer in nonlinear optical chromophores: Fullerene (C60) derivatives

•N,N-Dimethylanilin can narrow the energy gap between the HOMO and LUMO.•The order of is in roughly consistent with anisotropy polarizability.•N,N-Dimethylanilin significantly increases the first hyperpolarizabilities (βtot).•The enhancement of βtot is related to the intramolecular electron transfer.

The push-pull functionalized fullerenes consisting of multi-N,N-diethylamine donors covalently attached to N-methylpyrrolidine derivative of C60 have been designed and investigated. The structures and first hyperpolarizabilities of these fullerene derivatives were calculated using density functional theory. Furthermore, absorption spectra of the complexes along with electron density difference maps corresponding to the most intense electronic transitions were achieved by time-dependent density functional theory. It suggests that with the growing numbers of N,N-Dimethylanilin acting as electron-donating group, the polarizabilities, dipole moments and the first hyperpolarizabilits increase, however, transition energies of the crucial electronic transitions decrease and the absorption wavelength shows bathochromic effect. The excitation transitions have significant charge transfer character and, as a consequence, the novel complexes can behave as second-order nonlinear optical chromophores, in which the N,N-Dimethylanilin act as donors towards fullerenes.

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