É. Bardez, V. Alain, E. Destandau
Oct 19, 2001
Citations
0
Influential Citations
12
Citations
Journal
Journal of Physical Chemistry A
Abstract
Chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonic acid) is a chelating agent whose fluorogenic character has never been explained yet. The excited-state behavior of chromotropic acid itself has never been reported, despite its relationship with naphthols that are well-known photoacids. The present paper is accordingly devoted to a thorough investigation of chromotropic acid emission in aqueous solutions, which revealed its excited-state prototropic behavior in relation with the key role of the ground-state internal H-bond between the two −OH groups (displayed by the very different pKvalues, 5.4 and 15.6). Experiments were carried out in the whole acidity range (8 M HClO4 to 10 M NaOH) using steady-state and time-resolved fluorimetry. In concentrated HClO4, competitive quenching processes occurred, due to HClO4 itself and to water, respectively, but no photoinduced deprotonation was observed. The former quenching was confirmed by studying the emission of 2,6-naphthalenedisulfonic acid in the same ...