Anthracylmethyl crowns 1 and 2 show up to 30-fold increase in fluorescence emission intensity in the presence of saxitoxin in ethanol, and sixfold enhancement in 80% ethanol. The binding constant between saxitoxin and 1 is 3880 M-1 in ethanol and 1100 M-1 in 80% ethanol. (C) 1999 Elsevier Science Ltd. All rights reserved.