Effect of Crown Ether Ring Size on Binding and Fluorescence Response to Saxitoxin in Anthracylmethyl Monoaza Crown Ether Chemosensors.

Convenient macrocyclization synthetic routes for the preparation of different-sized monoaza anthracylmethyl crown ether chemsensors (15-crown-5, 18-crown-6, 21-crown-7, 24-crown-8 and 27-crown-9) are described. Evaluation of these crowns as chemosensors for saxitoxin revealed that the larger crowns have moderately higher binding constants, with the 27-crown-9 chemosensor having the largest binding constant: 2.29×10(5) M(-1). Fluorescence enhancements of 100% were observed at saxitoxin concentrations of 5 μM, which is close to the detection limit in mouse bioassay.