Blue-green photoluminescence from pyridine-C60 adduct

The freshly prepared solution of C60 in pyridine has a purple-pinkish color, which turns gradually into a brown color. We report for the first time the observation of a bright blue-green photoluminescence from the brown C60/pyridine solution upon UV excitation. The luminescent species is identified to be the zwitterionic adduct formed between pyridine and C60 as revealed by 1H-NMR, mass spectra, and the solvatochromic effect of the photoluminescence to protic solvent. The fluorescence excitation spectra of the luminescent species and the dependence of the luminescence on excitation wavelength are also reported. C70 in pyridine shows similar phenomena.