A reassessment of the association between azulene and [60]fullerene. Possible pitfalls in the determination of binding constants through fluorescence spectroscopy.

We show here that the recently reported surprisingly large association constant (K = 7.6 x 10(4) M(-1)) between azulene and [60]fullerene is due to experimental artifacts, pointing out potential errors in the characterization of association equilibria by fluorescence spectroscopy, and suggesting the best experimental practices.