Synthesis and optical properties of[C60/C70]fullerene derivatives containing spirobifluorene and imidazole units

Abstract

Aseries of [C60/C70]]fullerene derivatives containing different spirobifluorene and triphenyl imidazole were synthesized andconfirmed by IR, 1H NMR, 13C NMR, MALDI-TOF-MS. Their optical limiting properties were investigated by nanosecond and femtosecond laser systems. Results showed that fullerene derivatives exhibited high optical limiting properties.Lower OL thresholds of 13.7, 14.9, 15.3, 23.3, and 24.0 J/cm2were observed for C70-SBF, C60-TPI, C 60-SBF, C60-FSBF, and C60-BTPI respectively with the linear transmittance of 75%, which implied that these optical limiting properties increased with the degree of conjugation and electron-donating or electron-accepting abilities of donors or acceptors in donor-acceptor (D-A) structures. The strong D and A with large conjugation is an effective way to enhance OL properties.